Next Article in Journal
The Influence of Roughness of Surfaces on Wear Mechanisms in Metal–Rock Interactions
Previous Article in Journal
Photocatalytic Performance of Cementitious Composites Modified with Second-Generation Nano-TiO2 Dispersions: Influence of Composition and Granulation on NOx Purification Efficiency
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Coatings
Volume 15
Issue 2
10.3390/coatings15020149
coatings-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Self-Driven Miniature Sensing Technology Based on Cellulose-Based Triboelectric Nanogenerators in a Wearable Human Health Status Monitoring System

by
Na Xiao
1,
Longqing He
2 and
Kai Wang
2,*
1
Faculty of Engineering, Huanghe Science and Technology University, Zhengzhou 450061, China
2
College of Electrical Engineering, Weihai Innovation Research Institute, Qingdao University, Qingdao 266000, China
*
Author to whom correspondence should be addressed.
Coatings 2025, 15(2), 149; https://doi.org/10.3390/coatings15020149
Submission received: 27 December 2024 / Revised: 21 January 2025 / Accepted: 27 January 2025 / Published: 30 January 2025
Browse Figures
Versions Notes

Abstract

:
The progression of wearable technology has revealed that cellulose-based triboelectric nanogenerators (TENG) possess considerable promise in self-powered micro-sensing technology; this is attributed to their superior biocompatibility, sustainability, and mechanical characteristics. This paper aims to explore the application of the cellulose-based TENG self-powered micro-sensing technology in wearable systems for human health monitoring. First, the working principles and modes of TENG are summarized, along with the characteristics of the cellulose, nanocellulose, cellulose derivatives and the advantages of the cellulose-based TENG. Next, we discuss in detail the applications of the cellulose-based TENG in monitoring physiological parameters, such as heart rate, motion, respiration, and pulse, and we analyze their advantages and challenges in practical applications. Additionally, we explore the integration of the cellulose-based TENG human–machine interaction sensors in health monitoring devices. Finally, we outline the current challenges and future research directions in this field, including the enhancement of triboelectric performance, adaptability to diverse environments, controllable degradability, and multi-scenario real-world applications. This review provides a comprehensive perspective on the application of the cellulose-based TENG self-powered micro-sensing technology in wearable health monitoring systems and offers guidance for future research and development.

1. Introduction

In recent years, wearable devices have occupied a key position in the collection and analysis of health information and have become a powerful means of enabling the early detection, diagnosis, and treatment of diseases [1]. For the diagnosis and analysis of cardiovascular diseases, the long-term monitoring of physical signs, such as electrocardiogram (ECG), heart sounds, blood pressure, and pulse is often required [2,3]. However, wearable devices rely on conventional electrochemical batteries for their power supply, which not only results in larger wearable sensors and reduced wearing comfort, but also causes the problem of frequent charging or periodic replacement [4,5]. In view of this, wearable energy harvesters based on a variety of principles have been widely developed [6,7], including electrostatic, electromagnetic, thermoelectric, piezoelectric, and friction electric types. Among them, the triboelectric nanogenerator, as a kind of energy harvesting device [8,9,10], has shown a rapid development in the application of human health monitoring [11,12,13]. With the help of the TENG, the dispersed mechanical energy generated by the human body can be converted into sustained electrical energy to continuously supply energy for wearable devices [14,15,16] and to detect the physiological parameters and metabolic status of the human body, so as to achieve a comprehensive monitoring of human health [17,18]. In addition, TENG-based self-powered sensors have many advantages, such as ultra-high sensitivity, good adaptability, high flexibility, and excellent environmental friendliness [19,20,21].
TENGs are composed of triboelectric materials, substrates, and conductive materials. Traditional TENG triboelectric materials typically have disadvantages, such as non-renewability, difficulty in degradation, and significant environmental harm [22]. For example, the metal materials (Al, Cu) [23] are prone to oxidation or corrosion in harsh environments, affecting the performance stability and lifespan of TENGs. Synthetic polymers, such as polyamide (PA) [24] and polydimethylsiloxane (PDMS) [25], are non-renewable and non-biodegradable. Their post-processing can cause environmental pollution [26,27], limiting the further development of cost-effective and ecofriendly TENGs. Reducing e-waste and achieving sustainability has become a key research direction of TENGs. It has been reported that a thermoplastic polymer-based TENG was used in a sustainable marine monitoring system; its design is fully recyclable (AR-TENG), which significantly reduces the generation of e-waste [28]. In addition, a vitrimer composite based on polyimine/graphite polypropylene (PI/GP) has also been developed for a high-performance TENG, which not only exhibits excellent mechanical properties and self-healing capabilities, but also has recyclability [29]. Cellulose is one of the most abundant natural polymers on Earth [30]; it is characterized by wide availability, low cost, high strength, renewability, degradability, flexibility in modification, biocompatibility, environmental friendliness, and excellent electron-donating and -accepting capabilities [31]. It can serve as a structural support in materials, providing strength and flexibility to enhance performance. It can also act as a binder between different materials, enabling the fabrication of various composite materials and serving as an indispensable component in forming cellulose-based gel materials [32]. The chemical modifiability, mechanical properties, flexibility, and other advantageous characteristics of cellulose offer diverse options for TENG component design, making it adaptable to the fabrication and application of various materials. It is an excellent material for TENG production [33,34,35]. In terms of biodegradability, the all-cellulose TENG shows good degradability, and it can be completely degraded within 8 h under the action of cellulase [36]. Similarly, the TENG based on cellulose filter paper can completely disperse and dissolve in deionized water within 30 min under ultrasonic treatment, demonstrating its excellent biodegradability and environmental friendliness [37] These studies show that the cellulose-based TENG has significant advantages in terms of eco-friendliness and sustainability.
This paper systematically summarizes the application of the cellulose-based TENG self-powered micro-sensing technology in wearable human health monitoring systems. It introduces the fundamental working principles and four operational modes of the TENG, as well as the basic characteristics of cellulose, nanocellulose, cellulose derivatives, and the advantages of the cellulose-based TENG. Additionally, we discuss the application value of the cellulose-based TENG in monitoring physiological signals, such as body motion, respiration, cardiac activity, pulse, and tactile sensations, as well as in human–machine interaction systems. Addressing the critical issues and challenges of the cellulose-based TENG in terms of processing performance, stability, and applications, we propose several effective strategies and innovative approaches. Finally, we forecast the future prospects of the cellulose-based TENG as a multifunctional, flexible, and green energy device.

2. Overview of TENG and Cellulose-Based TENG

2.1. Working Principle

With the development of smart and miniaturized electronic products, a growing number of researchers have conducted extensive studies on portable, flexible, lightweight, and biocompatible electronic devices [38,39]. Reducing the size of electronic devices and lowering their power consumption have become urgent technical challenges and scientific problems to be addressed. In 2012, the research team led by Academician Zhong lin Wang [40] discovered during their study of piezoelectric nanogenerators that the triboelectric effect could convert mechanical energy into electrical energy. Through structural optimization and the surface modification of materials, they significantly enhanced the output performance of nanogenerators. Subsequently, they invented the triboelectric nanogenerator based on the triboelectric effect [41] and electrostatic induction [42,43]. Its model and structure are shown in Figure 1.
Utilizing the friction-induced electric effect, the TENG can convert mechanical energy into electrical energy and can drive microelectronic devices. The TENG is formed by stacking two materials (PET and Kapton) with distinctly different friction electric sequences and depositing a metal film as an electrode on the back side of the PET and Kapton. Due to the nanoscale roughness of the material surfaces, once the device is subjected to external forces, the two types of PET and Kapton rub against each other, generating an equal number of positive and negative friction charges on the surfaces of both [44,45]. The TENG device is subjected to successive external mechanical forces, thereby inducing a cyclic positional variation in the surface charges of the materials. This, in turn, instigates a periodic oscillation in the potential difference between the two electrodes. To maintain the electrostatic equilibrium of the electrodes, the electrons within the electrodes oscillate in the external circuit to counterbalance the potential difference. Consequently, the applied mechanical energy is transduced into electrical energy [46,47,48].
The friction nanogenerator has unique advantages over existing energy harvesting methods. First, it is a new type of generator based on new principles and methods, and it is likely to open up new research areas in energy harvesting using organic materials. Second, friction nanogenerators are designed and prepared using fewer materials and process steps; they utilize a simple, low-cost, engineering approach integrated with other processing technologies, which will facilitate large-scale industrial manufacturing and applications [49]. Finally, the TENG is an innovative self-driven device that can autonomously produce electrical impulses in reaction to environmental stimuli without requiring an external power source. The invention of friction nanogenerators is a revolutionary breakthrough in mechanical energy generation; they are self-driven systems that can be used as a continuous power source to power micro-devices [50,51,52,53]. Meanwhile the field of self-driven sensors based on friction electric nanogenerators has seen tremendous development and applications, such as human health monitoring, chemical detection, and environmental monitoring [54]

2.2. Operating Modes

The unique advantages of friction nanogenerators are diversified design, simple preparation, low cost, and multiple work modes, which can meet different application scenarios. The TENG has the following four basic modes: vertical contact separation mode, lateral sliding mode, single-electrode mode, and freestanding triboelectric layer mode [55,56,57], see Table 1.

2.2.1. Vertical Contact Separation Mode

In the vertical contact separation mode, the two friction layers periodically touch and separate in the vertical direction. When two friction layers come into contact, the charge is redistributed between the two surfaces through triboelectrification, resulting in charge separation. With the separation of the friction layer, electric charges accumulate on the surface of the friction layer, forming an electric potential difference. Since the electrodes are attached to the back of the friction layer, an electric potential difference is created between the electrodes, which drives electrons to flow in the external circuit [58]. In this mode, the output performance of the TENG mainly depends on the contact area of the friction layer, the separation speed, and the triboelectric properties of the material. This mode is suitable for applications that require high-voltage outputs, such as self-actuated sensors and energy harvesting devices, the working principles of which can be seen in Figure 2I.

2.2.2. Lateral Sliding Mode

Figure 2II shows the working principle of the lateral sliding TENG. The two friction layers slide relative to each other in the horizontal direction instead of simply contacting and separating. When the friction layers slide relative to each other, the charge is redistributed on the surface of the friction layers, resulting in a change in the potential difference between the electrodes. Electrons flow in the external circuit, with the direction and amount of flow depending on the polarity and charge distribution of the friction layer [59]. In contrast to the contact separation mode, the lateral slide mode is capable of producing a stable electrical energy output in continuous motion and is suitable for energy harvesting in dynamic environments, such as wearables and self-actuated sensors.

2.2.3. Single-Electrode Mode

In single-electrode mode, the TENG contains only one electrode and works by creating an electric potential difference with the ground. When contact and separation occurs between the friction layers, electric charges are generated and accumulated on the surface of the friction layer, resulting in a change in the electric potential difference between the electrode and the ground. The flow of electrons occurs between the electrode and the ground, and the current is output through an external circuit [60]. This mode, where the accumulation and release of charge directly drives the flow of electrons without the need for a second electrode, is particularly suitable for simplifying structures and reducing system complexity. The operational concept is illustrated in Figure 2III.

2.2.4. Freestanding Triboelectric Layer Mode

In the freestanding triboelectric layer mode, the TENG does not require external mechanical contact, but instead generates electrical energy by vibrating or moving the free-hanging friction layer through air or other media. In this mode, the vibration or movement of the friction layer causes the charge to be redistributed on the surface of the friction layer, resulting in an electric potential difference. Electrons flow in the external circuit, and the direction and amount of the flow depend on the potential difference between the electrode and the ground. In this mode, the TENG can directly generate electrical energy using the tiny amount of mechanical energy in the environment, which is particularly suitable for energy harvesting and self-actuated sensing applications [61]. The working principle is shown in Figure 2IV.

2.3. Cellulose-Based TENG for Sensing Technology

2.3.1. Basic Properties of Cellulose

Cellulose is the most abundant natural material in the world; it is widely found in most plants [62], some algae [63], and bacteria [64] and is an excellent environmentally friendly material that is widely available, inexpensive, renewable, and naturally degradable. Cellulose is a class of linear natural organic polymer compounds consisting of D-glucose units linked by 1,4-β-glycosidic bonds with the molecular formula (C6H10O5)n [65]. Cellulose molecules form protofibril (diameter of about 5 nm) by combination; the protofibril is further aggregated to form microfine fibers (straight warp of about 25~50 nm, approximate length of a few microns), which are then composed of cellulose fibers (diameter of 10~50 µm, length of 1~40 mm), as shown in Figure 3 [66]. Cellulose can be prepared into TENG friction material or substrate by vacuum filtration, electrostatic spinning, doping, and other processing methods and finally assembled into TENGs for various applications, as shown in Figure 4 [67,68,69,70].

2.3.2. Nanocellulose and Cellulose Derivatives

Nanocellulose refers to natural cellulose with a nanometer size in a certain dimension [71] and mainly includes cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), and bacterial cellulose (BC). In addition to the properties of natural cellulose, nanocellulose has excellent mechanical properties, large specific surface area, low density, good biocompatibility, natural degradation, and other excellent properties [72,73,74], and it can be used as friction materials in the TENG. Nanocellulose’s high specific surface area, high crystallinity, and excellent mechanical properties enable it to capture more frictional charge, significantly improve the charge density and output performance of the TENG, and improve the mechanical stability and durability of the TENG. At the same time, the nanoscale size effect and surface chemical reactivity of nanocellulose allow it to bind to the electrode material more efficiently, thereby improving the charge transfer efficiency of the TENG. Secondly, the biocompatibility and degradability of nanocellulose give it a unique advantage in wearable devices and environmentally friendly applications. In addition, nanocellulose can introduce different functional groups through chemical modification, thereby regulating its triboelectric polarity and further optimizing the performance of the TENG.
The cellulose functional group is relatively single (mainly hydroxyl group), but the reactivity is high [75]; so, by modifying the hydroxyl group of cellulose through oxidation, etherification, sulfonation, carboxylation, acetylation, grafting, cross-linking reactions, etc., a variety of cellulose derivatives can be produced, which can give the cellulose new properties, such as hydrophobicity, friction electrode properties (positive, negative, and size), etc. The various properties of cellulose derivatives make it possible to meet the requirements for the preparation of cellulose-based TENGs for various applications [76,77,78,79,80]. Table 2 shows examples of the applications of nanocellulose and cellulose derivatives as TENG friction materials.

2.3.3. Advantages of Cellulose-Based TENG

Currently, the mainstream triboelectric materials for the preparation of functional TENGs are metals, such as silver, copper, and aluminum, and polymers, such as polyamide (PA), polytetrafluoroethylene (PTFE), and fluorinated ethylene propylene (FEP), as shown in Table 3. Although it has excellent frictional power generation capacity, it is not easy to recycle and degrade, and excessive application of such materials will lead to resource waste and environmental pollution [20,21,23,25,31]. Therefore, biofriendly biodegradable friction nanogenerators for monitoring human physiological signals came into being.
Cellulose is inexpensive, high-strength, renewable, degradable, flexible in modification, biocompatible, and green and has excellent electron gain/loss capability, which provides a variety of choices for the design of TENG components; it can be adapted to a wide range of material preparations and applications, and it is a good material for the preparation of TENGs [18,32]. TENGs prepared based on cellulose materials have the advantages of safety and non-toxicity, low cost, simple structure, and green environmental protection, and they can simultaneously perform the dual functions of energy harvesting and signal monitoring, showing broad application prospects in the fields of energy harvesting, human–computer interaction, medicine and healthcare, and air purification [87,88,89].

3. Cellulose-Based TENG Sensing Technology for Health Monitoring Applications

The self-powered nature of the cellulose-based TENG makes the overall system more ecologically friendly, eliminates the dependency on traditional batteries, and lessens the amount of e-waste. Integrating the TENG with the nano-sensors enables the device to run autonomously without an external power source and to depend on the electricity supplied by the TENG to supply the nano-sensors. This integrated design also enables real-time monitoring of physiological parameters (e.g., heart rate, respiratory rate, etc.) during exercise or daily life, where the data are acquired by the nano-sensors and processed and transmitted using the energy supplied by the cellulose-based TENG to achieve all-around monitoring of the human body’s health (Figure 5). Real-time monitoring of the body’s status has demonstrated a tremendous potential for preventing and treating a range of illnesses, and it is projected to minimize the frequency of unplanned emergency events [17,18,90], see Table 4.

3.1. Motion Sensors

TENG-based human motion sensors use signals from TENGs installed in different parts of the human body (e.g., hands, elbows, armpits, knees, feet, etc.) to analyze the motion condition of the corresponding parts; then, the overall motion of the human body can be analyzed, such as bending and stretching of the limbs, walking, running, and jumping, etc. Zhu et al. [94] developed a sustainable high-performance TENG based on a polydopamine (PDA) and CNF composite membrane in conjunction with FEP, designated as PDA/CNF-TENG (refer to Figure 6a). The PDA/CNF composite membrane is characterized by its eco-friendliness and biodegradability, while the presence of internal amino and imine groups, along with its micro- and nano-scale surface structure, significantly enhances the triboelectric effect of the PDA/CNF-TENG. This TENG device can be integrated into various parts of the human body to effectively monitor human movement through the generation of stable, periodic, and reversible current signals. Bai et al. [36] produced a porous nanocomposite by introducing nano-alumina (Al2O3) into CA and then further prepared porous nanocomposite fabric (PNF) by using dry forming technology. Due to its non-toxicity, gentleness, excellent processing performance, strong film-forming ability, economy, biodegradability, and good biocompatibility, CA has become an ideal candidate for positively charged friction materials. PNF, as a positively charged friction material, is combined with the negatively charged LTV to form the PNF-TENG (Figure 6(b1,b2)), which is designed to monitor the state of the human body in real time during exercise and health training, proving its utility as a potential self-powered sensor. Shao et al. [95] incorporated BaTiO3 particles with a high dielectric constant into BC film and paired them with PDMS as triboelectric materials for the construction of TENGs; the aim was to collect energy generated by human movement. The TENG exhibited excellent stability and flexibility, making it easy to integrate with clothing or rehabilitation equipment to capture energy during human movement. The Cao team [96] developed a scalable, morphologically adaptive TENG that utilized CNF as a dispersion and locking medium to strengthen the connectivity of MXene nanosheets. The TENG can detect the frequency and amplitude of various physiological movements by being attached to human skin and clothing. At the same time, the CNF/MXene liquid electrode-based TENG (CM-TENG, Figure 6c) can also be combined with a multi-channel wireless signal transmission module to accurately monitor the bending of human joints through Bluetooth technology. Wang et al. [97] successfully prepared a TENG (CNC/PHB-TENG) composite of CNCs and polyhydroxybutyrate (PHB) using high-pressure molding technology (Figure 6(d1)). With the increase in CNC content, the CNC/PHB-TENG achieved a 5.7-fold and 12.5-fold increase in voltage and current output compared to the original PHB-based TENG (Figure 6(d2)). The device can effectively monitor various human movements in real time. Luo et al. [98] developed an ecofriendly and recyclable BC-based TENG self-energy sensor; the aim was to monitor motion status and identify improper motion posture to prevent sports injuries and to enhance the surface potential of the BC membrane by treating it with hydroxyethyl cellulose (HEC) solution. The BC/HEC-TENG can be easily attached to the upper part of the shoe. The output voltage and current show an obvious difference between normal walking and fast walking, and the output of fast walking even exceeds that of normal walking. In addition, if an individual has excessive pronation, the output performance of the inner heel will be higher than that of the outer heel, thus helping to adjust the movement posture of the individual (Figure 6e).

3.2. Breathing Sensors

The TENG can be embedded in clothing, and by driving the generator with the mechanical motion generated by human respiration, real-time monitoring of the respiration rate and pattern can be achieved. Wang et al. [86] developed a composite material based on cellulose nanocrystals and methylcellulose (MC), which was used as a positively charged friction layer, while pure MC films were used as a negatively charged friction layer. They combined these materials with water-soluble graphite electrodes to create a water-soluble triboelectric nanogenerator (WS-TENG) (Figure 7(a1,a2)). The WS-TENG is low-cost, lightweight, and biodegradable and can quickly dissolve in deionized water at room temperature, making it suitable for use as a disposable bandage sensor for monitoring human respiratory and physiological signals (Figure 7(a3)). The device has an output voltage range of 0 to 2 V (Figure 7(a4)) and is able to accurately identify different breathing patterns, including light breathing, normal breathing, deep breathing, and rapid breathing. Compared to conventional devices that require an external power supply, the WS-TENG reduces the inconvenience of carrying a power supply and has environmentally friendly natural degradation characteristics. Rajabi-Abhari et al. [68] formed a new composite material by mixing CNF, diatomite shell (DF), and silver nanowires (AgNW) and uniformly coated it on an aluminum electrode as a positively charged friction material. At the same time, they selected the flexible FEP film as the negatively charged friction material and then developed the DF-CNF-based TENG and applied it to the field of smart masks. The DF-CNF bio-composites exhibit excellent mechanical strength, rich electronic properties, and economical cost-effectiveness. The experimental results confirm that CNFs and DFs not only have good biocompatibility, but also high safety when making a wearable, skin-attached TENG. The smart mask can monitor the human respiratory rate and cough behavior according to changes in electrical signals caused by breathing, showing great application prospects in the field of health monitoring (Figure 7(b1,b2)). He et al. [99] formed an ideal two-dimensional hierarchical nanostructure by constructing one-dimensional CNFs on the backbone of cellulose microfibers (CMFs) to form a highly efficient, low-cost, and sustainable PM2.5 removal strategy (98.83%). Meanwhile, a new method was developed to prepare silver nanofiber membranes using CMFs/CNFs as templates, which had good antimicrobial activity. The respiration frequency and intensity were successfully detected by the cf-TENG’s unique power generation, which was dependent on different operating displacements and frequencies (Figure 7c). Zhang et al. [100] fabricated a biodegradable chitosan-CNT film and an Ecoflex-graphene (RC)-TENG with a raised structure. By incorporating CNT into chitosan and forming the raised Ecoflex structure with CNT, the acquisition of respiratory information was achieved (Figure 7(d1)). This led to the emergence of the RC-TENG-based wireless intelligent respiratory monitoring system (WIRMS), which provides a solution for real-time respiratory monitoring, diagnosis, and prevention of obstructive respiratory diseases. WIRMS demonstrates biocompatibility, stability, and high precision. Its real-time and lossless transmission and monitoring of respiratory information make it suitable for the aforementioned applications (Figure 7(d2–d4)).

3.3. Heart and Pulse Sensors

Given the body’s unique response to various diseases, monitoring physiological indicators, including heart rate, heartbeat, blood pressure, and pulse, is essential for doctors to diagnose and treat emergencies. In the field of health monitoring, friction nanogenerators have become one of the core tools. Zhang et al. [101] developed a geared TENG with a three-dimensional spatial framework, which effectively expanded the frictional contact area (Figure 8(a1)). During the preparation process, they carried out surface amination of the CNF and nano-silver coating treatment to develop an innovative simple CNF gear structure TENG. Thanks to its three-dimensional architecture, the TENG can not only generate electricity through contact separation, but can also collect energy through the sliding mode when subjected to lateral forces. This three-dimensional design not only increases the friction area, but also opens up new ways for energy harvesting. The number of gears has a significant effect on the performance of the TENG, which can generate a maximum open-circuit voltage of up to 286 V when optimized for three pairs of gears (Figure 8(a2)). The electricity generated is enough to directly light up 60 LED lights and acts as a self-powered sensor that responds sensitively to human contact and small changes caused by substrate vibration. Oh et al. [102] cleverly constructed a high-performance ferro-BC composite paper base TENG using filtering technology (Figure 8(b1)). The incorporation of silver nanowires (NWs) and BTO nanoparticles (NPs) into the BC substrate gives the paper-based materials excellent electrical conductivity and ferroelectric properties, respectively. In addition, they successfully prepared large-scale BC composite paper. The BC-TENG generates enough electricity to power a heart monitor and blood pressure monitor, enabling real-time tracking of a person’s heartbeat and breathing. They further explored the power generation efficiency of the BC-TENG by adjusting the external resistance load in the range of 10 kΩ to 1 GΩ. It was found that with the increase in external resistance load, the output current of the TENG showed a decreasing trend, while the output voltage showed an opposite trend (Figure 8(b2)). Li et al. [87] developed a modified Filipino capsule membrane-based friction nanogenerator (BN-TENG) (Figure 8(c1)). When utilized as a power source for an electrical stimulation system, the BN-TENG achieved peak output values of 34 V for voltage and 0.32 μA for current (Figure 8(c2)). Notably, the BN-TENG was fully biodegradable and absorbable in rats after completing its function. This innovation offers a promising approach for addressing heart conditions such as bradycardia and arrhythmia. Lin et al. [103] successfully developed PEO/cellulose composite paper (CCP) by cationizing cellulose fibers and combining them with polyethylene oxide (PEO), aiming to enhance the electrical output efficiency of the cellulose-based paper TENG. As shown in Figure 8(d1), the device is able to accurately measure the pulse of the human wrist through a health monitoring instrument. Pulse signals were effectively monitored both at rest and after exercise. Although the device voltage generated by the wrist pulse of a 29-year-old female subject did not exceed 25 mV, the device demonstrated excellent response performance in both states, and its signal curve showed good repeatability and stability (Figure 8(d2)). As a result, the device performs well in detecting vital signs, providing a cost-effective application path for medical diagnosis and disease prediction.

3.4. Tactile and Sweat Sensors

Tactile sensors cause TENG power generation by touch, resulting in changes in electrical signals, and real-time changes in the magnitude of the touch force also cause real-time changes in the electrical signals, making the response sensitive and timely. Yu et al. [104] introduced an integrated TENG device which was fabricated by vacuum filtration to incorporate silver nanowires and BaTiO3 particles into the BC matrix. Extended utilization of a mouse and keyboard may lead to knuckle damage. The devised device, when attached to the mouse and keyboard, generates frequencies that can serve as a reminder for the employees using them to take appropriate breaks. The voltage signals received exhibited diverse fluctuations due to the distinct states and clicking velocities of human touch devices (Figure 9b). Li et al. [105] developed a self-healing elastomer (GHEC) composed of glycerin-hydroxyethyl cellulose and a double-network (DN) hydrogel composed of polyacrylamide (PAM) and carrageenan. By placing the DN hydrogel between the two layers of GHEC, they produced a self-powered and self-healing TENG, called SS-TENG for short (Figure 9(a1,a2)). The presence of the GHEC layer gives the TENG self-healing properties. On the basis of the SS-TENG, they further developed a self-powered transparent tactile sensor with a 3 × 3 matrix arrangement, which can accurately sense spatial tactile signals, showing the potential to become a new generation of self-powered flexible display screen sensors. Varghese et al. [106] developed a TENG-based self-powered sensor using cellulose acetate nanofibers (CANF) and PDMS as basic materials (Figure 9(c1)). The sensor can detect a small force of 0.05 N and show a sensitivity of 3.67 V/N to a force below 1 N. It has potential commercial application prospects due to its low cost (Figure 9(c2)). These results mark an important advance in the application of nanocellulose-based nanogenerators in the field of biosensing. Qin et al. [107] constructed a self-healing flexible self-powered sweat sensor based on an oxidized cellulose nanofiber (TOCNF)-packaged PDMS composite material as a negative friction layer and a highly selective hydrophobic ion-selective membrane (ISM) as a positive friction layer. The sensor can quantitatively monitor the change in electrolyte ion concentration in human sweat in real time. The single-electrode TENG-based self-powered sensor generates electrical signals at potential changes caused by ion density differences through a periodic contact and separation mechanism. The highly negative triboelectric properties of PDMS enhance the electrical output of the sensor and improve the detection sensitivity to changes in the concentration of target ions (Figure 9d).

3.5. Human–Computer Interaction

Artificial intelligence (AI) and neuromorphic devices for self-powered sensors involve the integration of AI algorithms and neuromorphic computing architectures into sensor systems to enable autonomous and intelligent data processing and decision making while enabling self-power. The background of this field includes the convergence of AI, neuroscience, and sensor technologies to develop energy-efficient and adaptive sensor systems that can mimic the biological nervous system for efficient information processing. This approach aims to create self-powered sensors that can mimic the cognitive processes of the human brain, enabling advanced pattern recognition, adaptive learning, and real-time data analysis without relying on an external power source. The goal is to advance the development of energy-autonomous sensor networks that are capable of complex context-aware data processing and interpretation with applications in areas such as robotics, healthcare, and environmental monitoring.
The cellulose-based TENG is used as a sensor in the field of human–computer interaction, and the electrical signals generated by it can be used to control mechanical devices. Zhang et al. [108] developed an environmentally friendly energy harvesting and interaction device, which was made of all-cellulose composite materials. This all-cellulose TENG is capable of producing a maximum open-circuit voltage of up to 29 V, a short-circuit current of 0.6μA, and an output power of 3μW. The demonstrated power is sufficient to drive commercially available electronic devices, and the output signal can be used directly as a trigger signal for human–computer interaction, such as the control of a wearable electronic piano (Figure 10(a1)). The study also included biodegradability tests, which confirmed that BC and BC-carbon nanotube-polypyrrole (PPy) films can be completely degraded within 8 h, and the remaining CNT can be recycled. As a biopolymer produced by bacterial fermentation, BC has the characteristics of high purity, high porosity, excellent liquid/gas permeability, good biocompatibility, strong mechanical properties, and easy doping of conductive materials. Combined with efficient energy harvesting, the BC-based TENG shows great promise in the fields of implantable electronic devices, temporary energy harvesting devices, biosafe human–machine interfaces, and electronic devices for artificial organs/tissues adapted to biological tissues. Chen et al. [109] conceived and constructed a TENG based on cellulose-derived materials through a straightforward fabrication technique. Leveraging the notably disparate friction poles between CCP and NCM, along with their microstructural characteristics (namely corrugated and porous formations), the CCP/NCM-based P-TENG manifested remarkable triboelectric attributes, such as a substantial power density of 16.1 W/m2 and a robust durability exceeding 10,000 cycles (Figure 10(b1)). Employing the P-TENG array for self-powered human–computer interaction within paper pianos, the depressed keys (i.e., P-TENG) generate electrical energy for capacitor charging. The voltage fluctuation is then utilized to regulate the sound program as an input cue. Since an external power source is unnecessary for signal generation in this context, self-powered human–computer interaction is accomplished via the P-TENG (Figure 10(b2,b3)). The P-TENG further displays the capacity to harvest mechanical energy, in addition to self-powered sensing and human–computer interfacing capabilities. He et al. [110] built a wireless human–computer interaction system integrating paper TENG and signal processing circuits for document management. The paper TENG is placed at the bottom of the document to generate electrical signals when the document is moved. These signals activate the remote control and infrared (IR) sensor, and the signal processor captures the IR signal and displays the corresponding file number on the interface. In addition, they developed an intelligent computing platform equipped with 16 separate grid TENGs to act as function keys. Users can enter numbers and perform mathematical calculations by touching these keys (Figure 10c). Shi et al. [111] used kapok cellulose nanofiber film (KCNF) to develop an electrode material with biocompatibility, acid and alkali resistance, ductility, breathability, degradability, and high sensitivity for the development of wearable sensors that can collect biomechanical energy and control wireless systems. The material exhibits excellent ductility (25%) and tensile strength (42 MPa) and can be degraded in the natural environment without chemical treatment, with a maximum power density of 0.8 Wm−2. Compared to the TENG composed of kapok TEMPO oxidized cellulose membrane (KTCF), the KCNF-based TENG achieved a significant increase in output voltage and current, from 18 V to 59 V and from 0.4 μA to 2 μA (Figure 10(d2,d3)). Due to the fast response speed of the KCNF-TENG sensor, it can play a role not only in the human–computer interaction control of computer games, but also as a transient password input device and for adjusting the height of the patient care bed (Figure 10(d1)). This research provides an environmentally friendly and sustainable solution for the development of low-cost, environmentally friendly, and recyclable wearable sensor technology. Jin et al. [89] assembled a highly sensitive single-electrode TENG based on CaCl2/PVA/keratin and Ecoflex. They devised portable systems for monitoring finger activities, including finger curvature identification, gesture recognition, and object shape discrimination. The final optimized machine learning algorithm attained an accuracy of 98.1% for object shape recognition. The application of triboelectric flexible sensors to soft robots can not only enhance the sensing capacity and bionic performance of the robots, but also contribute to the improvement of their intelligence and autonomy owing to their energy harvesting and self-powered properties. With further exploration, triboelectric sensors are anticipated to assume a more significant role in the domain of soft robotics.
Table 4. Cellulose-based TENG applications.
Table 4. Cellulose-based TENG applications.
Type of MaterialApplication ScenarioMaterial EffectsReference
Cellulose and nitrocellulose paperHarvests energy from human movementAs a friction layer, excellent triboelectric properties[67]
HCPHarvests energy from human movementAs a friction layer, waterproof[112]
BCHarvests energy from human movementAs a friction layer, good flexibility[95]
PDA/CNFHuman motion sensorAs a friction layer, it can be degraded naturally[94]
Al2O3/CAHuman motion sensorAs a friction layer, non-toxic and non-irritating[36]
CNFHuman motion sensorAs a friction layer, dispersant and interlocking agent[96]
CNC/PHBHuman motion sensorAs a friction layer, excellent triboelectric properties[97]
BC/HECHuman motion sensorAs a friction layer, excellent triboelectric properties[98]
CNC/MCRespiratory rate sensorAs a friction layer, it is lightweight and biodegradable[88]
CNF/DF/AgNWRespiratory rate sensorAs a friction layer, low-cost, high-strength[68]
CMFs/CNFsRespiratory rate sensorAs a friction layer, low-cost and sustainable[99]
CNT/EcoflexRespiratory rate sensorAs a friction layer, biodegradable[100]
CNFHeart sensorAs a friction layer, increases the friction area[101]
BC/NWs/NPsHeart sensorAs a friction layer, high-strength[102]
BNHeart sensorAs a friction layer, biodegradable[87]
PEO/CCPPulse sensorAs a friction layer, excellent triboelectric properties[103]
BaTiO3/BCTactile sensorsAs a friction layer, excellent triboelectric properties[104]
GHECTactile sensorsAs a friction layer, it provides self-healing ability[105]
CANFTactile sensorsAs a friction layer, low-cost[106]
TOCNF/ISMSweat sensorAs a friction layer, excellent triboelectric properties[107]
BC/CNT/PPyHuman–computer interactionAs a friction layer, biodegradable, high-strength[108]
CCP/NCMHuman–computer interactionDurable as a friction layer[109]
KCNFHuman–computer interactionBiodegradable as friction layer, high sensitivity[110]
CaCl2/PVA/Keratin/EcoflexHuman–computer interactionHigh sensitivity as a friction layer[89]

4. Summary and Prospects

Friction nanogenerators can make equipment self-powered without an external power supply, which can not only streamline the equipment and reduce the inconvenience of an external power supply, but also save energy and reduce the pollution caused by power generation, as well as reduce the consumption and pollution caused by the production, application, and recycling of batteries. Cellulose has the advantages of high strength, natural degradation, biocompatibility, etc., and the modification of cellulosic materials is flexible and simple; as they are widely used, these advantages and characteristics have caused cellulose-based functional materials to become attractive substrates or components of the TENG. The cellulose-based TENG can make its own energy generation; at the same time, it can be naturally degraded and play a role in protecting the environment and has applications in energy harvesting, sensors, environmental monitoring. Research on sterilization and disinfection has been the basis of a number of fields of application; in the field of wearable human health monitoring applications, considerable achievements have been made, and there is huge potential for medical health monitoring.
Although the cellulose-based TENG has made progress in areas such as energy harvesting and flexible electronics, its usefulness in improving triboelectric properties, environmental adaptability, controlled degradation, and multi-environment practical applications has not been fully demonstrated. Specifically, the complexity of some cellulose modification processes has extended the development cycle of TENGs, and many cellulose-based TENGs are still in the laboratory handmade stage, far from reaching the requirements of commercial-scale production. In addition, the surface micro-/nanostructure of some cellulose-based TENGs may gradually degrade during long-term use, which will seriously affect their long-term stability and power output. Sensitivity to environmental factors, such as humidity, temperature, light, and wind speed, also weakens the stability of the cellulose-based TENG. In order to accelerate the commercialization of the cellulose-based TENG and enhance the user experience, a wider range of application areas needs to be explored. At the same time, the diversity of the cellulose structure affects its processing properties, and it is a technical challenge to accurately control the microstructure and functionalization of the cellulose-based TENG. Future research is needed to further explore how to establish a direct correlation between the performance requirements of TENG components and the properties of cellulose-based materials.
In the progression of the cellulose-based TENG, the following aspects are worthy of in-depth exploration: (i) Studies should focus on improving the electrical performance and energy output capacity of the cellulose-based TENG to meet the practical application of the health monitoring sensor in high-power demand scenarios such as wireless communication. The chemical and physical modification strategies of cellulosic materials were explored to enhance their triboelectric properties. It is necessary to optimize the structural design of TENG and develop multilayer and micro-/nanostructures to improve energy conversion efficiency. Research is needed on efficient electrode materials and energy management systems to achieve effective collection and utilization of electrical energy. It is also necessary to solve the stability and adaptability of the TENG under different environmental conditions. (ii) Frictionally electroactive layers typically necessitate high dielectric characteristics and strong electron affinity, which facilitates the induction of a high surface charge density and an extended charge decay period. Consequently, the efficient modification of cellulose-based materials can be investigated by attaching functional groups possessing high friction polarity to cellulose, thereby enhancing the charge density on the cellulose surface. (iii) The environmental adaptability of the TENG, encompassing traits such as mechanical deformability, durability, waterproof capabilities, self-healing properties, corrosion resistance, optical transparency, and ecological friendliness, can be harnessed. Cellulose and its derivative substances can be engineered as flexible substrates, intelligent coatings, and adhesives to fulfill the demands of these attributes. (iv) Degradability holds significant importance for the application of the TENG both outside and within the human body. During the modification of cellulose-based materials, a proper equilibrium between their mechanical stability and biodegradability must be maintained. (v) The multi-scenario on-site practical applications of the TENG mandate the satisfaction of the various properties mentioned above. Thus, the mechanical, optical, and electrical features of cellulose-based materials should be comprehensively contemplated during chemical modification and processing. Based on the multifunctional utilization of cellulosic materials in TENG development, the concurrent application of cellulosic materials in the fabrication of other integrated devices, such as cellulose-based supercapacitors and lithium-ion batteries, can also be taken into account. (vi) With regard to the integrated utilization of environmental energy sources on Earth, like solar, thermal, and air energy, the further development of some novel cellulose-based friction electric–electromagnetic, friction electric–thermal electric, and solar cell/friction electric hybrid nanogenerators is required to enable the concurrent acquisition of multiple energy sources within a single apparatus.
To sum up, forthcoming efforts ought to center around the advancement of sophisticated cellulose-based functional materials that possess rapid preparation capacities, outstanding friction electrode attributes, favorable morphologies, abrasion resistance, and anti-aging characteristics. The employment of cellulose-based materials can be conducive to the evolution and commercialization of high-performance, environmentally friendly, and low-cost TENGs. These TENGs are applicable in energy harvesting, information dissemination, human–computer interaction, and the Internet of Things (IoT) within an ecologically sustainable distributed network. This can exert a substantial influence on the energy ecosystem and render energy utilization more convenient and efficient. Cellulose-based materials will progressively attract more attention and find broader applications in the construction of green TENGs.

Author Contributions

Investigation, L.H.; writing—original draft preparation, N.X.; writing—review and editing, K.W.; supervision, K.W.; project administration, L.H. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Acknowledgments

This work was supported by the Youth Innovation Technology Project of Higher School in Shandong Province (No. 2022KJ139).

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Yao, S.; Swetha, P.; Zhu, Y. Nanomaterial-Enabled Wearable Sensors for Healthcare. Adv. Healthc. Mater. 2018, 7, 1700889. [Google Scholar] [CrossRef] [PubMed]
  2. Khan, B.; Riaz, Z.; Ahmad, R.U.S.; Khoo, B.L. Advancements in wearable sensors for cardiovascular disease detection for health monitoring. Mater. Sci. Eng. R-Rep. 2024, 159, 100804. [Google Scholar] [CrossRef]
  3. Liu, W.; Wang, X. Recent advances of nanogenerator technology for cardiovascular sensing and monitoring. Nano Energy 2023, 117, 108910. [Google Scholar] [CrossRef] [PubMed]
  4. Hu, S.; Chang, S.; Xiao, G.; Lu, J.; Gao, J.; Zhang, Y.; Tao, Y. A Stretchable Multimode Triboelectric Nanogenerator for Energy Harvesting and Self-Powered Sensing. Adv. Mater. Technol. 2022, 7, 2100870. [Google Scholar] [CrossRef]
  5. Mule, A.R.; Dudem, B.; Graham, S.A.; Yu, J.S. Humidity Sustained Wearable Pouch-Type Triboelectric Nanogenerator for Harvesting Mechanical Energy from Human Activities. Adv. Funct. Mater. 2019, 29, 1807779. [Google Scholar] [CrossRef]
  6. Kadarina, T.; Priambodo, R. Monitoring heart rate and SpO2 using Things board IoT platform for mother and child preventive healthcare. IOP Conf. Ser. Mater. Sci. Eng. 2018, 453, 012028. [Google Scholar]
  7. Zois, D.-S. IEEE: Sequential Decision-Making in Healthcare IoT: Real-Time Health Monitoring, Treatments and Interventions. In Proceedings of the IEEE 3rd World Forum on Internet of Things (WF-IoT), Reston, VA, USA, 12–14 December 2016; pp. 24–29. [Google Scholar]
  8. An, J.; Wang, Z.M.; Jiang, T.; Liang, X.; Wang, Z.L. Whirling-Folded Triboelectric Nanogenerator with High Average Power for Water Wave Energy Harvesting. Adv. Funct. Mater. 2019, 29, 1904867. [Google Scholar] [CrossRef]
  9. Chen, J.; Yang, J.; Li, Z.; Fan, X.; Zi, Y.; Jing, Q.; Guo, H.; Wen, Z.; Pradel, K.C.; Niu, S.; et al. Networks of Triboelectric Nanogenerators for Harvesting Water Wave Energy: A Potential Approach toward Blue Energy. ACS Nano 2015, 9, 3324–3331. [Google Scholar] [CrossRef]
  10. Jiang, T.; Pang, H.; An, J.; Lu, P.; Feng, Y.; Liang, X.; Zhong, W.; Wang, Z.L. Robust Swing-Structured Triboelectric Nanogenerator for Efficient Blue Energy Harvesting. Adv. Energy Mater. 2020, 10, 2000064. [Google Scholar] [CrossRef]
  11. Chen, X.; Xie, X.; Liu, Y.; Zhao, C.; Wen, M.; Wen, Z. Advances in healthcare electronics enabled by triboelectric nanogenerators. Adv. Funct. Mater. 2020, 30, 2004673. [Google Scholar] [CrossRef]
  12. Cheng, M.; Zhu, G.; Zhang, F.; Tang, W.; Jianping, S.; Yang, J.; Zhu, L. A review of flexible force sensors for human health monitoring. J. Adv. Res. 2020, 26, 53–68. [Google Scholar] [CrossRef]
  13. Zeng, W.; Shu, L.; Li, Q.; Chen, S.; Wang, F.; Tao, X.-M. Fiber-Based Wearable Electronics: A Review of Materials, Fabrication, Devices, and Applications. Adv. Mater. 2014, 26, 5310–5336. [Google Scholar] [CrossRef]
  14. Rao, J.; Chen, Z.; Zhao, D.; Ma, R.; Yi, W.; Zhang, C.; Liu, D.; Chen, X.; Yang, Y.; Wang, X.; et al. Tactile electronic skin to simultaneously detect and distinguish between temperature and pressure based on a triboelectric nanogenerator. Nano Energy 2020, 75, 105073. [Google Scholar] [CrossRef]
  15. Ren, Z.; Wang, Z.; Liu, Z.; Wang, L.; Guo, H.; Li, L.; Li, S.; Chen, X.; Tang, W.; Wang, Z.L. Energy Harvesting from Breeze Wind (0.7–6 ms−1) Using Ultra-Stretchable Triboelectric Nanogenerator. Adv. Energy Mater. 2020, 10, 2001770. [Google Scholar] [CrossRef]
  16. Rong, X.; Zhao, J.; Guo, H.; Zhen, G.; Yu, J.; Zhang, C.; Dong, G. Material Recognition Sensor Array by Electrostatic Induction and Triboelectric Effects. Adv. Mater. Technol. 2020, 5, 2000641. [Google Scholar] [CrossRef]
  17. Aladren, A.; Lopez-Nicolas, G.; Puig, L.; Guerrero, J.J. Navigation Assistance for the Visually Impaired Using RGB-D Sensor with Range Expansion. IEEE Syst. J. 2016, 10, 922–932. [Google Scholar] [CrossRef]
  18. Ramadhan, A.J. Wearable Smart System for Visually Impaired People. Sensors 2018, 18, 843. [Google Scholar] [CrossRef] [PubMed]
  19. Jiang, P.; Zhang, L.; Guo, H.; Chen, C.; Wu, C.; Zhang, S.; Wang, Z. Signal output of triboelectric nanogenerator at oil–water–solid multiphase interfaces and its application for dual-signal chemical sensing. Adv. Mater. 2019, 31, 1902793. [Google Scholar] [CrossRef] [PubMed]
  20. Liu, W.; Wang, X.; Song, Y.; Cao, R.; Wang, L.; Yan, Z.; Shan, G. Self-powered forest fire alarm system based on impedance matching effect between triboelectric nanogenerator and thermosensitive sensor. Nano Energy 2020, 73, 104843. [Google Scholar] [CrossRef]
  21. Luo, J.; Wang, Z.; Xu, L.; Wang, A.C.; Han, K.; Jiang, T.; Lai, Q.; Bai, Y.; Tang, W.; Fan, F.R.; et al. Flexible and durable wood-based triboelectric nanogenerators for self-powered sensing in athletic big data analytics. Nat. Commun. 2019, 10, 5147. [Google Scholar] [CrossRef]
  22. Chao, S.; Ouyang, H.; Jiang, D.; Fan, Y.; Li, Z. Triboelectric nanogenerator based on degradable materials. EcoMat 2021, 3, e12072. [Google Scholar] [CrossRef]
  23. Yang, W.; Chen, J.; Zhu, G.; Yang, J.; Bai, P.; Su, Y.; Jing, Q.; Cao, X.; Wang, Z.L. Harvesting energy from the natural vibration of human walking. ACS Nano 2013, 7, 11317–11324. [Google Scholar] [CrossRef] [PubMed]
  24. Zhao, K.; Wang, Z.L.; Yang, Y. Self-Powered Wireless Smart Sensor Node Enabled by an Ultra-Stable, Highly-Efficient, and Super-Hydrophobic-Surfaces-Based Triboelectric Nanogenerator. ACS Nano 2016, 10, 9044. [Google Scholar] [CrossRef] [PubMed]
  25. Liu, Z.; Muhammad, M.; Cheng, L.; Xie, E.; Han, W. Improved output performance of triboelectric nanogenerators based on polydimethylsiloxane composites by the capacitive effect of embedded carbon nanotubes. Appl. Phys. Lett. 2020, 117, 143903. [Google Scholar] [CrossRef]
  26. Li, H.; Zhao, S.; Du, X.; Wang, J.; Cao, R.; Xing, Y.; Li, C. A Compound Yarn Based Wearable Triboelectric Nanogenerator for Self-Powered Wearable Electronics. Adv. Mater. Technol. 2018, 3, 1800065. [Google Scholar] [CrossRef]
  27. Zhu, M.; Huang, Y.; Ng, W.S.; Liu, J.; Wang, Z.; Wang, Z.; Hu, H.; Zhi, C. 3D spacer fabric based multifunctional triboelectric nanogenerator with great feasibility for mechanized large-scale production. Nano Energy 2016, 27, 439–446. [Google Scholar] [CrossRef]
  28. Ahn, J.; Kim, J.S.; Jeong, Y.; Hwang, S.; Yoo, H.; Jeong, Y.; Gu, J.; Mahato, M.; Ko, J.; Jeon, S.; et al. All-Recyclable Triboelectric Nanogenerator for Sustainable Ocean Monitoring Systems. Adv. Energy Mater. 2022, 12, 2201341. [Google Scholar] [CrossRef]
  29. Rajabi-Abhari, A.; Li, P.; Bagheri, M.H.; Khan, A.A.; Hao, C.; Tanguy, N.R.; Ban, D.; Yu, L.; Yan, N. Self-healable, recyclable, and mechanically robust vitrimer composite for high-performance triboelectric nanogenerators and self-powered wireless electronics. Nano Energy 2024, 131, 110306. [Google Scholar] [CrossRef]
  30. Muhd Julkapli, N.; Bagheri, S. Nanocellulose as a green and sustainable emerging material in energy applications: A review. Polym. Adv. Technol. 2017, 28, 1583–1594. [Google Scholar] [CrossRef]
  31. Zhang, M.; Du, H.; Liu, K.; Nie, S.; Xu, T.; Zhang, X.; Si, C. Fabrication and applications of cellulose-based nanogenerators. Adv. Compos. Hybrid Mater. 2021, 4, 865–884. [Google Scholar] [CrossRef]
  32. Niu, Z.; Cheng, W.; Cao, M.; Wang, D.; Wang, Q.; Han, J.; Long, Y.; Han, G. Recent advances in cellulose-based flexible triboelectric nanogenerators. Nano Energy 2021, 87, 106175. [Google Scholar] [CrossRef]
  33. De France, K.; Zeng, Z.; Wu, T.; Nystrom, G. Functional Materials from Nanocellulose: Utilizing Structure-Property Relationships in Bottom-Up Fabrication. Adv. Mater. 2021, 33, 2000657. [Google Scholar] [CrossRef]
  34. Ferreira, F.V.; Otoni, C.G.; De France, K.J.; Barud, H.S.; Lona, L.M.F.; Cranston, E.D.; Rojas, O.J. Porous nanocellulose gels and foams: Breakthrough status in the development of scaffolds for tissue engineering. Mater. Today 2020, 37, 126–141. [Google Scholar] [CrossRef]
  35. Vanderfleet, O.M.; Cranston, E.D. Production routes to tailor the performance of cellulose nanocrystals. Nat. Rev. Mater. 2021, 6, 124–144. [Google Scholar] [CrossRef]
  36. Bai, Z.; Xu, Y.; Li, J.; Zhu, J.; Gao, C.; Zhang, Y.; Wang, J.; Guo, J. An Eco-friendly Porous Nanocomposite Fabric-Based Triboelectric Nanogenerator for Efficient Energy Harvesting and Motion Sensing. Acs Appl. Mater. Interfaces 2020, 12, 42880–42890. [Google Scholar] [CrossRef]
  37. Yang, M.; Tian, X.; Hua, T. Green and recyclable cellulose based TENG for sustainable energy and human-machine interactive system. Chem. Eng. J. 2022, 442, 136150. [Google Scholar] [CrossRef]
  38. Chung, H.U.; Kim, B.H.; Lee, J.Y.; Lee, J.; Xie, Z.; Ibler, E.M.; Lee, K.; Banks, A.; Jeong, J.Y.; Kim, J.; et al. Binodal, wireless epidermal electronic systems with in-sensor analytics for neonatal intensive care. Science 2019, 363, eaau0780. [Google Scholar] [CrossRef] [PubMed]
  39. Rajewsky, N.; Almouzni, G.; Gorski, S.A.; Aerts, S.; Amit, I.; Bertero, M.G.; Bock, C.; Bredenoord, A.L.; Cavalli, G.; Chiocca, S.; et al. LifeTime and improving European healthcare through cell-based interceptive medicine. Nature 2020, 587, 377–386. [Google Scholar] [CrossRef] [PubMed]
  40. Fan, F.-R.; Tian, Z.-Q.; Wang, Z. Flexible triboelectric generator. Nano Energy 2012, 1, 328–334. [Google Scholar] [CrossRef]
  41. Baytekin, H.; Patashinski, A.; Branicki, M.; Baytekin, B.; Soh, S.; Grzybowski, B.A. The mosaic of surface charge in contact electrification. Science 2011, 333, 308–312. [Google Scholar] [CrossRef]
  42. Wang, Z.L.; Chen, J.; Lin, L. Progress in triboelectric nanogenerators as a new energy technology and self-powered sensors. Energy Environ. Sci. 2015, 8, 2250–2282. [Google Scholar] [CrossRef]
  43. Wang, Z. Triboelectric nanogenerators as new energy technology and self-powered sensors—Principles, problems and perspectives. Faraday Discuss. 2014, 176, 447–458. [Google Scholar] [CrossRef] [PubMed]
  44. Matsunaga, M.; Hirotani, J.; Kishimoto, S.; Ohno, Y. High-output, transparent, stretchable triboelectric nanogenerator based on carbon nanotube thin film toward wearable energy harvesters. Nano Energy 2020, 67, 104297. [Google Scholar] [CrossRef]
  45. Wu, C.; Wang, A.C.; Ding, W.; Guo, H.; Wang, Z.L. Triboelectric Nanogenerator: A Foundation of the Energy for the New Era. Adv. Energy Mater. 2019, 9, 1802906. [Google Scholar] [CrossRef]
  46. Chen, X.; Gao, L.; Chen, J.; Lu, S.; Zhou, H.; Wang, T.; Wang, A.; Zhang, Z.; Guo, S.; Mu, X.; et al. A chaotic pendulum triboelectric-electromagnetic hybridized nanogenerator for wave energy scavenging and self-powered wireless sensing system. Nano Energy 2020, 69, 104440. [Google Scholar] [CrossRef]
  47. Luo, J.; Xu, L.; Tang, W.; Jiang, T.; Fan, F.R.; Pang, Y.; Chen, L.; Zhang, Y.; Wang, Z.L. Direct-Current Triboelectric Nanogenerator Realized by Air Breakdown Induced Ionized Air Channel. Adv. Energy Mater. 2018, 8, 1800889. [Google Scholar] [CrossRef]
  48. Quan, T.; Yang, Y. Fully enclosed hybrid electromagnetic-triboelectric nanogenerator to scavenge vibrational energy. Nano Res. 2016, 9, 2226–2233. [Google Scholar] [CrossRef]
  49. Khandelwal, G.; Raj, N.P.M.J.; Kim, S.-J. Triboelectric nanogenerator for healthcare and biomedical applications. Nano Today 2020, 33, 100882. [Google Scholar] [CrossRef]
  50. Jiang, H.; Lv, X.; Wang, K. Application of triboelectric nanogenerator in self-powered motion detection devices: A review. APL Mater. 2024, 12, 070601. [Google Scholar] [CrossRef]
  51. Pan, Y.; Song, J.; Wang, K. Research Progress and Prospects of Liquid–Liquid Triboelectric Nanogenerators: Mechanisms, Applications, and Future Challenges. ACS Appl. Electron. Mater. 2024, 7, 1–12. [Google Scholar] [CrossRef]
  52. Pan, Y.; Zhu, Y.; Li, Y.; Liu, H.; Cong, Y.; Li, Q.; Wu, M. Homonuclear transition-metal dimers embedded monolayer C2N as promising anchoring and electrocatalytic materials for lithium-sulfur battery: First-principles calculations. Appl. Surf. Sci. 2023, 610, 155507. [Google Scholar] [CrossRef]
  53. Qi, G.; Du, G.; Wang, K. Progress in estimating the state of health using transfer learning-based electrochemical impedance spectroscopy of lithium-ion batteries. Ionics 2025, 1–13. [Google Scholar] [CrossRef]
  54. Gao, M.; Yang, Z.; Choi, J.; Wang, C.; Dai, G.; Yang, J. Triboelectric Nanogenerators for Preventive Health Monitoring. Nanomaterials 2024, 14, 336. [Google Scholar] [CrossRef] [PubMed]
  55. Dong, K.; Peng, X.; Wang, Z. Fiber/fabric-based piezoelectric and triboelectric nanogenerators for flexible/stretchable and wearable electronics and artificial intelligence. Adv. Mater. 2020, 32, 1902549. [Google Scholar] [CrossRef]
  56. Wang, S.; Lin, L.; Wang, Z. Triboelectric nanogenerators as self-powered active sensors. Nano Energy 2015, 11, 436–462. [Google Scholar] [CrossRef]
  57. Zhu, G.; Peng, B.; Chen, J.; Jing, Q.; Wang, Z. Triboelectric nanogenerators as a new energy technology: From fundamentals, devices, to applications. Nano Energy 2015, 14, 126–138. [Google Scholar] [CrossRef]
  58. Zhao, L.; Li, H.; Meng, J.; Li, Z. The recent advances in self-powered medical information sensors. Infomat 2020, 2, 212–234. [Google Scholar] [CrossRef]
  59. Xia, Z.; Feng, P.-Y.; Jing, X.; Li, H.; Mi, H.-Y.; Liu, Y. Design and optimization principles of cylindrical sliding triboelectric nanogenerators. Micromachines 2021, 12, 567. [Google Scholar] [CrossRef]
  60. Zhang, Z.; Bai, Y.; Xu, L.; Zhao, M.; Shi, M.; Wang, Z.L.; Lu, X. Triboelectric nanogenerators with simultaneous outputs in both single-electrode mode and freestanding-triboelectric-layer mode. Nano Energy 2019, 66, 104169. [Google Scholar] [CrossRef]
  61. Niu, S.; Liu, Y.; Chen, X.; Wang, S.; Zhou, Y.S.; Lin, L.; Xie, Y.; Wang, Z. Theory of freestanding triboelectric-layer-based nanogenerators. Nano Energy 2015, 12, 760–774. [Google Scholar] [CrossRef]
  62. Zhang, H.; Nie, S.; Qin, C.; Wang, S. Products Removal of hexenuronic acid to reduce AOX formation in hot chlorine dioxide bleaching of bagasse pulp. Ind. Crops Prod. 2019, 128, 338–345. [Google Scholar] [CrossRef]
  63. Beaumont, M.; Tran, R.; Vera, G.; Niedrist, D.; Rousset, A.; Pierre, R.; Shastri, V.P.; Forget, A. Hydrogel-forming algae polysaccharides: From seaweed to biomedical applications. Biomacromolecules 2021, 22, 1027–1052. [Google Scholar] [CrossRef] [PubMed]
  64. Shi, Z.; Zhang, Y.; Phillips, G.O.; Yang, G. Utilization of bacterial cellulose in food. Food Hydrocoll. 2014, 35, 539–545. [Google Scholar] [CrossRef]
  65. Klemm, D.; Heublein, B.; Fink, H.P.; Bohn, A. Cellulose: Fascinating biopolymer and sustainable raw material. Angew. Chem. Int. Ed. 2005, 44, 3358–3393. [Google Scholar] [CrossRef] [PubMed]
  66. Zhu, H.; Luo, W.; Ciesielski, P.N.; Fang, Z.; Zhu, J.; Henriksson, G.; Himmel, M.E.; Hu, L. Wood-derived materials for green electronics, biological devices, and energy applications. Chem. Rev. 2016, 116, 9305–9374. [Google Scholar] [CrossRef]
  67. Gu, L.; German, L.; Li, T.; Li, J.; Shao, Y.; Long, Y.; Wang, J.; Wang, X. Interfaces Energy harvesting floor from commercial cellulosic materials for a self-powered wireless transmission sensor system. ACS Appl. Mater. Interfaces 2021, 13, 5133–5141. [Google Scholar] [CrossRef] [PubMed]
  68. Rajabi-Abhari, A.; Kim, J.-N.; Lee, J.; Tabassian, R.; Mahato, M.; Youn, H.J.; Lee, H.; Oh, I.-K. Diatom bio-silica and cellulose nanofibril for bio-triboelectric nanogenerators and self-powered breath monitoring masks. ACS Appl. Mater. Interfaces 2020, 13, 219–232. [Google Scholar] [CrossRef]
  69. Sardana, S.; Kaur, H.; Arora, B.; Aswal, D.K.; Mahajan, A. Self-powered monitoring of ammonia using an MXene/TiO2/cellulose nanofiber heterojunction-based sensor driven by an electrospun triboelectric nanogenerator. ACS Sens. 2022, 7, 312–321. [Google Scholar] [CrossRef] [PubMed]
  70. Zhou, J.; Wang, H.; Du, C.; Zhang, D.; Lin, H.; Chen, Y.; Xiong, J. Cellulose for sustainable triboelectric nanogenerators. Adv. Energy Sustain. Res. 2022, 3, 2100161. [Google Scholar] [CrossRef]
  71. Hao, X.; Mou, K.; Jiang, X.; Cha, R. High-value applications of nanocellulose. Pap. Biomater. 2017, 2, 58–64. [Google Scholar] [CrossRef]
  72. Abitbol, T.; Rivkin, A.; Cao, Y.; Nevo, Y.; Abraham, E.; Ben-Shalom, T.; Lapidot, S.; Shoseyov, O. Nanocellulose, a tiny fiber with huge applications. Curr. Opin. Biotechnol. 2016, 39, 76–88. [Google Scholar] [CrossRef]
  73. Mondal, S. Preparation, properties and applications of nanocellulosic materials. Carbohydr. Polym. 2017, 163, 301–316. [Google Scholar] [CrossRef]
  74. Sun, Y.; Chu, Y.; Wu, W.; Xiao, H. Nanocellulose-based lightweight porous materials: A review. Carbohydr. Polym. 2021, 255, 117489. [Google Scholar] [CrossRef] [PubMed]
  75. Tortorella, S.; Vetri Buratti, V.; Maturi, M.; Sambri, L.; Comes Franchini, M.; Locatelli, E. Surface-modified nanocellulose for application in biomedical engineering and nanomedicine: A review. Int. J. Nanomed. 2020, 15, 9909–9937. [Google Scholar] [CrossRef] [PubMed]
  76. Ren, J.; Ma, J.; Wang, H.; Yu, T.; Wang, K. A comprehensive review on research methods for lithium-ion battery of state of health estimation and end of life prediction: Methods, properties, and prospects. Prot. Control Mod. Power Syst. 2024, 1–20. [Google Scholar] [CrossRef]
  77. Shang, Y.; Wang, S.; Tang, N.; Fu, Y.; Wang, K. Research progress in fault detection of battery systems: A review. J. Energy Storage 2024, 98, 113079. [Google Scholar] [CrossRef]
  78. Wang, W.; Yang, D.; Huang, Z.; Hu, H.; Wang, L.; Wang, K. Electrodeless nanogenerator for dust recover. Energy Technol. 2022, 10, 2200699. [Google Scholar] [CrossRef]
  79. Xing, Q.; Zhang, M.; Fu, Y.; Wang, K. Transfer learning to estimate lithium-ion battery state of health with electrochemical impedance spectroscopy. J. Energy Storage 2025, 110, 115345. [Google Scholar] [CrossRef]
  80. Yi, Z.; Wang, S.; Li, Z.; Wang, L.; Wang, K. A Novel Approach for State of Health Estimation and Remaining Useful Life Prediction of Supercapacitors Using an Improved Honey Badger Algorithm Assisted Hybrid Neural Network. Prot. Control Mod. Power Syst. 2024, 9, 1–18. [Google Scholar] [CrossRef]
  81. Nie, S.; Fu, Q.; Lin, X.; Zhang, C.; Lu, Y.; Wang, S. Enhanced performance of a cellulose nanofibrils-based triboelectric nanogenerator by tuning the surface polarizability and hydrophobicity. Chem. Eng. J. 2021, 404, 126512. [Google Scholar] [CrossRef]
  82. Kim, H.-J.; Yim, E.-C.; Kim, J.-H.; Kim, S.-J.; Park, J.-Y.; Oh, I.-K. Bacterial Nano-Cellulose Triboelectric Nanogenerator. Nano Energy 2017, 33, 130–137. [Google Scholar] [CrossRef]
  83. Somseemee, O.; Sae-Oui, P.; Siriwong, C. Bio-based epoxidized natural rubber/chitosan/cellulose nanocrystal composites for enhancing mechanical properties, self-healing behavior and triboelectric nanogenerator performance. Cellulose 2022, 29, 8675–8693. [Google Scholar] [CrossRef]
  84. Fan, C.; Huang, J.; Mensah, A.; Long, Z.; Sun, J.; Wei, Q. A high-performance and biodegradable tribopositive poly-e-caprolactone/ethyl cellulose material. Cell Rep. Phys. Sci. 2022, 3, 101012. [Google Scholar] [CrossRef]
  85. Bai, Z.; Xu, Y.; Zhang, Z.; Zhu, J.; Gao, C.; Zhang, Y.; Jia, H.; Guo, J. Highly flexible, porous electroactive biocomposite as attractive tribopositive material for advancing high-performance triboelectric nanogenerator. Nano Energy 2020, 75, 104884. [Google Scholar] [CrossRef]
  86. Wang, N.; Yang, D.; Zhang, W.; Feng, M.; Li, Z.; Ye, E.; Loh, X.J.; Wang, D. Deep Trap Boosted Ultrahigh Triboelectric Charge Density in Nanofibrous Cellulose-Based Triboelectric Nanogenerators. Acs Appl. Mater. Interfaces 2023, 15, 997–1009. [Google Scholar] [CrossRef] [PubMed]
  87. Jiang, W.; Li, H.; Liu, Z.; Li, Z.; Tian, J.; Shi, B.; Zou, Y.; Ouyang, H.; Zhao, C.; Zhao, L.; et al. Fully Bioabsorbable Natural-Materials-Based Triboelectric Nanogenerators. Adv. Mater. 2018, 30, 1801895. [Google Scholar] [CrossRef]
  88. Wang, T.; Li, S.; Tao, X.; Yan, Q.; Wang, X.; Chen, Y.; Huang, F.; Li, H.; Chen, X.; Bian, Z. Fully biodegradable water-soluble triboelectric nanogenerator for human physiological monitoring. Nano Energy 2022, 93, 106787. [Google Scholar] [CrossRef]
  89. Zhang, Z.; Cai, J. A Triboelectric Joint Sensor Imitating Soft Robot for Human Joint Rehabilitation Monitoring. Nano 2022, 17, 2250059. [Google Scholar] [CrossRef]
  90. Bai, J.; Lian, S.; Liu, Z.; Wang, K.; Liu, D. Smart Guiding Glasses for Visually Impaired People in Indoor Environment. IEEE Trans. Consum. Electron. 2017, 63, 258–266. [Google Scholar] [CrossRef]
  91. Shi, K.; Zou, H.; Sun, B.; Jiang, P.; He, J.; Huang, X. Dielectric modulated cellulose paper/PDMS-based triboelectric nanogenerators for wireless transmission and electropolymerization applications. Adv. Funct. Mater. 2020, 30, 1904536. [Google Scholar] [CrossRef]
  92. Ashammakhi, N.; Hernandez, A.L.; Unluturk, B.D.; Quintero, S.A.; de Barros, N.R.; Hoque Apu, E.; Bin Shams, A.; Ostrovidov, S.; Li, J.; Contag, C. Biodegradable implantable sensors: Materials design, fabrication, and applications. Adv. Funct. Mater. 2021, 31, 2104149. [Google Scholar] [CrossRef]
  93. Chen, S.; Qi, J.; Fan, S.; Qiao, Z.; Yeo, J.C.; Lim, C. Flexible wearable sensors for cardiovascular health monitoring. Adv. Healthc. Mater. 2021, 10, 2100116. [Google Scholar] [CrossRef] [PubMed]
  94. Zhu, Q.; Wang, T.; Wei, Y.; Sun, X.; Zhang, S.; Wang, X.; Luo, L. Low-cost, environmentally friendly and high-performance cellulose-based triboelectric nanogenerator for self-powered human motion monitoring. Cellulose 2022, 29, 8733–8747. [Google Scholar] [CrossRef]
  95. Shao, Y.; Feng, C.; Deng, B.; Yin, B.; Yang, M. Facile method to enhance output performance of bacterial cellulose nanofiber based triboelectric nanogenerator by controlling micro-nano structure and dielectric constant. Nano Energy 2019, 62, 620–627. [Google Scholar] [CrossRef]
  96. Cao, W.; Ouyang, H.; Xin, W.; Chao, S.; Ma, C.; Li, Z.; Chen, F.; Ma, M. A Stretchable Highoutput Triboelectric Nanogenerator Improved by MXene Liquid Electrode with High Electronegativity. Adv. Funct. Mater. 2020, 30, 2004181. [Google Scholar] [CrossRef]
  97. Wang, C.; Lu, L.; Li, W.; Shao, D.; Zhang, C.; Lu, J.; Yang, W. Green-in-green biohybrids as transient biotriboelectric nanogenerators. iScience 2022, 25, 105494. [Google Scholar] [CrossRef]
  98. Luo, C.; Shao, Y.; Yu, H.; Ma, H.; Zhang, Y.; Yin, B.; Yang, M. Improving the Output Performance of Bacterial Cellulose-Based Triboelectric Nanogenerators by Modulating the Surface Potential in a Simple Method. Acs Sustain. Chem. Eng. 2022, 10, 13050–13058. [Google Scholar] [CrossRef]
  99. He, X.; Zou, H.; Geng, Z.; Wang, X.; Ding, W.; Hu, F.; Zi, Y.; Xu, C.; Zhang, S.L.; Yu, H.; et al. A Hierarchically Nanostructured Cellulose Fiber-Based Triboelectric Nanogenerator for Self-Powered Healthcare Products. Adv. Funct. Mater. 2018, 28, 1805540. [Google Scholar] [CrossRef]
  100. Zhang, M.; Wen, Y.; Xie, Z.; Liu, B.; Sun, F.; An, Z.; Zhong, Y.; Feng, Q.; Zhao, T.; Mao, Y. Wireless Sensing System Based on Biodegradable Triboelectric Nanogenerator for Evaluating Sports and Sleep Respiratory. Macromol. Rapid Commun. 2024, 45, 2400151. [Google Scholar] [CrossRef]
  101. Zhang, C.; Lin, X.; Zhang, N.; Lu, Y.; Wu, Z.; Liu, G.; Nie, S. Chemically functionalized cellulose nanofibrils-based gear-like triboelectric nanogenerator for energy harvesting and sensing. Nano Energy 2019, 66, 104126. [Google Scholar] [CrossRef]
  102. Oh, H.; Kwak, S.S.; Kim, B.; Han, E.; Lim, G.-H.; Kim, S.-W.; Lim, B. Highly Conductive Ferroelectric Cellulose Composite Papers for Efficient Triboelectric Nanogenerators. Adv. Funct. Mater. 2019, 29, 1904066. [Google Scholar] [CrossRef]
  103. Lin, C.; Zhao, H.; Huang, H.; Ma, X.; Cao, S. PEO/cellulose composite paper based triboelectric nanogenerator and its application in human-health detection. Int. J. Biol. Macromol. 2023, 228, 251–260. [Google Scholar] [CrossRef] [PubMed]
  104. Yu, H.; Shao, Y.; Luo, C.; Li, Y.; Ma, H.-Z.; Zhang, Y.-H.; Yin, B.; Shen, J.; Yang, M. Bacterial cellulose nanofiber triboelectric nanogenerator based on dielectric particles hybridized system. Compos. Part A-Appl. Sci. Manuf. 2021, 151, 106646. [Google Scholar] [CrossRef]
  105. Li, X.; Xiang, S.; Ling, D.; Zhang, S.; Li, C.; Dai, R.; Zhu, P.; Liu, X.; Pan, Z. Stretchable, self-healing, transparent macromolecular elastomeric gel and PAM/carrageenan hydrogel for self-powered touch sensors. Mater. Sci. Eng. B Adv. Funct. Solid-State Mater. 2022, 283, 115832. [Google Scholar] [CrossRef]
  106. Varghese, H.; Hakkeem, H.M.A.; Farman, M.; Thouti, E.; Pillai, S.; Chandran, A. Self-powered flexible triboelectric touch sensor based on micro-pyramidal PDMS films and cellulose acetate nanofibers. Results Eng. 2022, 16, 100550. [Google Scholar] [CrossRef]
  107. Qin, Y.; Mo, J.; Liu, Y.; Zhang, S.; Wang, J.; Fu, Q.; Wang, S.; Nie, S. Stretchable Triboelectric Self-Powered Sweat Sensor Fabricated from Self-Healing Nanocellulose Hydrogels. Adv. Funct. Mater. 2022, 32, 1904066. [Google Scholar] [CrossRef]
  108. Zhang, J.; Hu, S.; Shi, Z.; Wang, Y.; Lei, Y.; Han, J.; Xiong, Y.; Sun, J.; Zheng, L.; Sun, Q.; et al. Eco-friendly and recyclable all cellulose triboelectric nanogenerator and self-powered interactive interface. Nano Energy 2021, 89, 106354. [Google Scholar] [CrossRef]
  109. Chen, S.; Jiang, J.; Xu, F.; Gong, S. Crepe cellulose paper and nitrocellulose membrane-based triboelectric nanogenerators for energy harvesting and self-powered human-machine interaction. Nano Energy 2019, 61, 69–77. [Google Scholar] [CrossRef]
  110. He, X.; Zi, Y.; Yu, H.; Zhang, S.L.; Wang, J.; Ding, W.; Zou, H.; Zhang, W.; Lu, C.; Wang, Z.L. An ultrathin paper-based self-powered system for portable electronics and wireless human-machine interaction. Nano Energy 2017, 39, 328–336. [Google Scholar] [CrossRef]
  111. Shi, Y.; Lin, C.; Deng, P.; Cao, L.N.; Wang, W.; Li, W.; Lin, H.; Yang, Y.; Wang, H.; Ye, M.; et al. Self-powered wearable human-computer interaction system based on kapok cellulose nanofibers. Chem. Eng. J. 2024, 488, 151059. [Google Scholar] [CrossRef]
  112. Lin, C.; Huang, H.; Zhao, H.; Cao, S.; Ma, X. Acid- and Alkali-Resistant and High-Performance Cellulose Paper-Based Triboelectric Nanogenerator by Controlling the Surface Hydrophobicity. ACS Sustain. Chem. Eng. 2022, 10, 13669–13679. [Google Scholar] [CrossRef]
Coatings 15 00149 g001
Figure 1. Structure and working principle of the triboelectric nanogenerator [40].
Figure 1. Structure and working principle of the triboelectric nanogenerator [40].
Coatings 15 00149 g001
Coatings 15 00149 g002
Figure 2. Structural diagrams and working principles of four types of friction nanogenerators (a is the model diagram and b is the structure diagram).
Figure 2. Structural diagrams and working principles of four types of friction nanogenerators (a is the model diagram and b is the structure diagram).
Coatings 15 00149 g002
Coatings 15 00149 g003
Figure 3. Schematic diagram of the structure and morphology of graded protofibers of lignocellulosic fibers.
Figure 3. Schematic diagram of the structure and morphology of graded protofibers of lignocellulosic fibers.
Coatings 15 00149 g003
Coatings 15 00149 g004
Figure 4. Schematic diagram of cellulose-based TENG application.
Figure 4. Schematic diagram of cellulose-based TENG application.
Coatings 15 00149 g004
Coatings 15 00149 g005
Figure 5. Application trend diagram of cellulose-based TENG in health monitoring system [82,91,92,93].
Figure 5. Application trend diagram of cellulose-based TENG in health monitoring system [82,91,92,93].
Coatings 15 00149 g005
Coatings 15 00149 g006
Figure 6. (a) Schematic of the TENG assembly structure. (b1) Schematic of the preparation process of PNF [36]. (b2) Structural design and application of the PNF-TENG [36]. (c) Schematic of the CM-TENG used for energy harvesting and biomechanical sensing [95]. (d1) Schematic of the CNC/PHB nanocomposite preparation and the application of flexible sensors based on CNC/PHB nanocomposites [97]. (d2) Voltage and current outputs of CNC/PHB-based TENG [97]. (e) The short-circuit current and open-circuit voltage of TENG and BH-PVDF TENG under different moving states were measured by the preparation process and motion posture of BH film [98].
Figure 6. (a) Schematic of the TENG assembly structure. (b1) Schematic of the preparation process of PNF [36]. (b2) Structural design and application of the PNF-TENG [36]. (c) Schematic of the CM-TENG used for energy harvesting and biomechanical sensing [95]. (d1) Schematic of the CNC/PHB nanocomposite preparation and the application of flexible sensors based on CNC/PHB nanocomposites [97]. (d2) Voltage and current outputs of CNC/PHB-based TENG [97]. (e) The short-circuit current and open-circuit voltage of TENG and BH-PVDF TENG under different moving states were measured by the preparation process and motion posture of BH film [98].
Coatings 15 00149 g006
Coatings 15 00149 g007
Figure 7. (a1) Schematic of TENG in contact separation mode between CNC/MC film adhered to graphite electrode and PTFE [86]. (a2) Structural design and components of TENG [86]. (a3) Schematic of real-time monitoring of respiration with TENG attached to the abdomen [86]. (a4) Voltage signals of TENG [86]. (b1) Schematic of the preparation process of DF-CNF composites and the biocompatibility of the DF-CNF-based TENG schematic [68]. (b2) Self-powered biocompatible smart mask for human respiration sensing and health monitoring [68]. (c) Schematic, microstructure, and photographs of cellulose fiber-based friction nanogenerator (cf-TENG) [99]. (d1) Schematic and structure of RC-TENG [100]. (d2) Output of the RC-TENG during deep breathing [100]. (d3) Electrical characteristics of the RC-TENG output during slow breathing [100]. (d4) Electrical output characteristics of RC-TENG during rapid breathing [100].
Figure 7. (a1) Schematic of TENG in contact separation mode between CNC/MC film adhered to graphite electrode and PTFE [86]. (a2) Structural design and components of TENG [86]. (a3) Schematic of real-time monitoring of respiration with TENG attached to the abdomen [86]. (a4) Voltage signals of TENG [86]. (b1) Schematic of the preparation process of DF-CNF composites and the biocompatibility of the DF-CNF-based TENG schematic [68]. (b2) Self-powered biocompatible smart mask for human respiration sensing and health monitoring [68]. (c) Schematic, microstructure, and photographs of cellulose fiber-based friction nanogenerator (cf-TENG) [99]. (d1) Schematic and structure of RC-TENG [100]. (d2) Output of the RC-TENG during deep breathing [100]. (d3) Electrical characteristics of the RC-TENG output during slow breathing [100]. (d4) Electrical output characteristics of RC-TENG during rapid breathing [100].
Coatings 15 00149 g007
Coatings 15 00149 g008
Figure 8. (a1) Schematic of the structure of a TENG [101]. (a2) Open-circuit voltages of TENG with different gear-like structures [101]. (b1) Schematic of the structure of a BC-TENG [102]. (b2) Output voltages and currents [102]. (c1) Structural diagram of a typical BN-TENG device [87]. (c2) Measured output voltages and currents of a BN-TENG [87]. (d1) Device output voltages induced by the wrist pulse before and after the motion signal [103]. (d2) Wave profile during one wrist pulse cycle [103].
Figure 8. (a1) Schematic of the structure of a TENG [101]. (a2) Open-circuit voltages of TENG with different gear-like structures [101]. (b1) Schematic of the structure of a BC-TENG [102]. (b2) Output voltages and currents [102]. (c1) Structural diagram of a typical BN-TENG device [87]. (c2) Measured output voltages and currents of a BN-TENG [87]. (d1) Device output voltages induced by the wrist pulse before and after the motion signal [103]. (d2) Wave profile during one wrist pulse cycle [103].
Coatings 15 00149 g008
Coatings 15 00149 g009
Figure 9. (a1) Detailed preparation diagram of SS-TENG [105]. (a2) Photographs of the actual SS-TENG. Scale bar: 0.5 cm [105]. (b) Schematic structure, output voltage, and current of the BC-based TENG [104]. (c1) Schematic diagram of the friction electric touch sensor and the actual image of the sensor [106]. (c2) Sensitivity of 0.05-1 N and 1-10 N [106]. (d) Cellulose-based conductive hydrogel for self-powered perspiration sensing [107].
Figure 9. (a1) Detailed preparation diagram of SS-TENG [105]. (a2) Photographs of the actual SS-TENG. Scale bar: 0.5 cm [105]. (b) Schematic structure, output voltage, and current of the BC-based TENG [104]. (c1) Schematic diagram of the friction electric touch sensor and the actual image of the sensor [106]. (c2) Sensitivity of 0.05-1 N and 1-10 N [106]. (d) Cellulose-based conductive hydrogel for self-powered perspiration sensing [107].
Coatings 15 00149 g009
Coatings 15 00149 g010
Figure 10. (a1) Schematic diagram of wearable electronic piano based on all-cellulose TENG [108]. (b1) P-TENG structure diagram for energy collection and self-powered human–machine interaction [109]. (b2) Circuit diagram of paper piano connected to computer through microcontroller [109]. (b3) Demonstration of songs played on self-powered paper piano [109]. (c) Photos of the library management system through document movement. The insert image shows the PHNG photo assembled at the bottom of the document, numbered 1-6 from left to right. Photo of a paper calculator triggered by the finger-touch action function. Insert image shows a photo of a paper finger touching a calculator [110]. (d1) Schematic diagram of the self-powered wearable KCNF-TENG sensor and the working principle of the self-powered wearable sensor control system [111]. (d2) Open-circuit voltage [111]. (d3) Short-circuit current [111].
Figure 10. (a1) Schematic diagram of wearable electronic piano based on all-cellulose TENG [108]. (b1) P-TENG structure diagram for energy collection and self-powered human–machine interaction [109]. (b2) Circuit diagram of paper piano connected to computer through microcontroller [109]. (b3) Demonstration of songs played on self-powered paper piano [109]. (c) Photos of the library management system through document movement. The insert image shows the PHNG photo assembled at the bottom of the document, numbered 1-6 from left to right. Photo of a paper calculator triggered by the finger-touch action function. Insert image shows a photo of a paper finger touching a calculator [110]. (d1) Schematic diagram of the self-powered wearable KCNF-TENG sensor and the working principle of the self-powered wearable sensor control system [111]. (d2) Open-circuit voltage [111]. (d3) Short-circuit current [111].
Coatings 15 00149 g010
Table 1. Comparison of TENG operating modes.
Table 1. Comparison of TENG operating modes.
NumberOperating ModeAdvantageDrawback
1Vertical contact separation modeStable and high output, difficult to achieve air fault conditionsMore complex structures and manufacturing processes
2Lateral sliding modeCharge due to back and forth motionWear and tear issues
3Single-electrode modeEasy to design and manufacture with one free layerNegatively affected by the electrostatic shielding effect
4Freestanding triboelectric layer modeHigh output performance, high energy conversion efficiencyComplex structures and manufacturing processes
Table 2. Nanocellulose and cellulose derivatives.
Table 2. Nanocellulose and cellulose derivatives.
NanocelluloseCategorizationEffectReference
CNFAs a friction layer, it enhances the hardness and tensile strength of the composite material, so that the mechanical properties of the material can be improved.[81]
BCAs a friction layer, the abundance of polar hydroxyl groups on the surface gives it strong chemical reaction activity, while the large aspect ratio of CNF can provide mechanical support for the TENG, and make it have certain strength and flexibility.[82]
CNCAs a friction layer, it enhances the flexibility, biocompatibility, and eco-friendliness of the TENG.[83]
Cellulose derivativeCategorizationModification methodModification effectReference
Ethyl cellulose (EC)EtherificationEnhanced friction electrical properties[84]
Cellulose acetate (CA)EsterificationEnhanced friction electrical properties[85]
CNF-SO3NaSulfonationEnhanced friction electrical properties[86]
Table 3. Comparison between cellulose and traditional triboelectric materials.
Table 3. Comparison between cellulose and traditional triboelectric materials.
Comparison ItemCellulose Triboelectric MaterialsMetal Triboelectric MaterialsPolymer Triboelectric Materials
Source and SustainabilityRenewable, widely available (e.g., plant fibers)Non-renewable, based on metal oresNon-renewable, petroleum-based synthetic materials
Environmental FriendlinessBiodegradable, environmentally friendlyNon-biodegradable, potential for resource waste and environmental pollutionMost are non-biodegradable, with potential environmental impact
CostLow costHigher cost, especially for precious metalsVaries by material, some are expensive
Mechanical PropertiesGood flexibility, foldable, cuttableRigid, some metals are brittleFlexibility varies by material, some are brittle
Triboelectric PerformanceCan be significantly enhanced through modification (e.g., chemical grafting, composite modification)Good conductivity, but limited triboelectric performanceSome materials (e.g., PTFE) have excellent triboelectric performance
BiocompatibilityHigh, suitable for biomedical and wearable applicationsLow, some metals may cause allergic reactionsSome materials have poor biocompatibility
Electrode CompatibilityCan be used as electrode materials (e.g., conductive cellulose paper)High conductivity, but may increase device weightConductivity varies by material, but some require additional electrodes
ProcessabilityEasy to process, can be modified through various methodsProcessing is more complex and requires specific techniquesDiverse processing methods, but some materials are difficult to process
Extreme Environment ResistanceResistant to high temperatures, humidity, and strong lightHigh-temperature resistance, but corrosion resistance needs optimizationSome polymers experience performance degradation in high-temperature and high-humidity environments
Application FieldsSelf-powered wearable devices, high-temperature sensing, intelligent monitoringElectronic devices, sensors, etc.Energy harvesting, electronic devices, etc.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Xiao, N.; He, L.; Wang, K. Self-Driven Miniature Sensing Technology Based on Cellulose-Based Triboelectric Nanogenerators in a Wearable Human Health Status Monitoring System. Coatings 2025, 15, 149. https://doi.org/10.3390/coatings15020149

AMA Style

Xiao N, He L, Wang K. Self-Driven Miniature Sensing Technology Based on Cellulose-Based Triboelectric Nanogenerators in a Wearable Human Health Status Monitoring System. Coatings. 2025; 15(2):149. https://doi.org/10.3390/coatings15020149

Chicago/Turabian Style

Xiao, Na, Longqing He, and Kai Wang. 2025. "Self-Driven Miniature Sensing Technology Based on Cellulose-Based Triboelectric Nanogenerators in a Wearable Human Health Status Monitoring System" Coatings 15, no. 2: 149. https://doi.org/10.3390/coatings15020149

APA Style

Xiao, N., He, L., & Wang, K. (2025). Self-Driven Miniature Sensing Technology Based on Cellulose-Based Triboelectric Nanogenerators in a Wearable Human Health Status Monitoring System. Coatings, 15(2), 149. https://doi.org/10.3390/coatings15020149

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop