Search Results (88)

Magnetically actuated soft robots enable untethered operation in confined and complex environments; however, achieving controllable directional locomotion in structurally symmetric systems remains a fundamental challenge due to intrinsic force cancellation under uniform fields. Here, we present a modular strategy that integrates assembled programmable magnetization with energy-biased symmetry-breaking joints to overcome this limitation. By embedding hard-magnetic NdFeB microparticles into an Ecoflex matrix, discrete magnetic units with programmable magnetization are fabricated and assembled into higher-order architectures. We show that asymmetric film constraints prescribe joint polarity and bias strain-energy distribution during actuation, producing distinct deformation modes (folding versus bending) under identical magnetic inputs. This energy asymmetry breaks the balanced response of symmetric structures, enabling net directional motion under spatially uniform magnetic fields. Based on this principle, a segmented crawler achieves a maximum speed of 5.42 mm s⁻¹ under a half-wave magnetic field, while a quadruped robot realizes programmable multi-directional locomotion (±X, ±Y) via dual-field coupling, reaching a maximum speed of 3.125 mm s⁻¹. These results demonstrate that modular magnetization and joint-mediated energy bias can cooperatively generate controllable directional locomotion through mechanically encoded symmetry breaking. This work provides a scalable design framework for programmable magnetic soft robots under spatially uniform magnetic fields. Full article

This work presents the design, development, and experimental validation of an inductive sensing system for monitoring prosthetic socket fit variations caused by residual limb volume fluctuations. The system aims to reduce the risk of discomfort and tissue injury by measuring the distance between the outer rigid socket and the inner silicone elastomeric liner worn in direct contact with the residual limb. The sensing architecture consists of a portable data acquisition unit, an LC resonator sensor mounted on the inner surface of the rigid socket, and a magnetic silicone target attached to the external surface of the liner. Multiple configurations of LC resonators and magnetic targets were designed and evaluated. The results indicate that a medium-sized coil (outer diameter = 28 mm, capacitance = 181 pF) combined with a 1 mm thick silicone target made of Ecoflex™ 00-50 with 70 wt% NdFeB microparticles provides the most stable and sensitive performance. Experiments demonstrated stable distance detection up to 7 mm, with the resonant-frequency shift (relative to the baseline condition) varying from −31.37 kHz at 0 mm to −2.94 kHz at 7.00 mm, for a total shift range of 29.84 kHz. Environmental tests showed minimal drift, with frequency variations below 0.40 kHz across temperature (25–60 °C) and humidity (50–90% RH) changes. In vitro validation using a high-fidelity residual limb simulator and an adjustable socket reproduced controlled residual limb volume variations of 300 mL (i.e., +7.5%), resulting in repeatable resonant-frequency changes within 3.15–3.17 MHz with measurement variability ($u_A$, Type A) below 0.13 kHz. Full article

This study investigates flexoelectricity in the pyramid- and truncated-pyramid-patterned contact interface of a NOA-63/Ecoflex (N/E) triboelectric nanogenerator (TENG) operating in contact–separation mode. Microscale pyramidal and truncated pyramidal arrays were fabricated using silicon molds and paired with an Ecoflex™ 00-10 elastomer substrate, and the structural integrity of the arrays was confirmed by scanning electron microscopy. Combining experimental results with established knowledge of soft-polymer indentation mechanics and hard-to-hard flexoelectric behavior, the surface charge density (σ) and flexoelectric coefficient (μ_flexo) were determined to be 8.48 × 10⁻⁶ C/m² and 2.95 × 10⁻¹¹ C/m, respectively. These parameters were incorporated into a total charge equation to estimate charge output for both pyramidal and truncated pyramidal N/E TENG arrays under varying applied loads. The proposed model can adequately predict the charge output of pyramidal and truncated pyramidal N/E TENGs. Full article

Soft actuators are increasingly being used in robotics and biomedical applications. They use hyperelastic materials, such as silicone rubber, to generate large reversible deformations. However, it is not easy to model the mechanical behavior of silicone rubber under large deformations. It is difficult to accurately predict its nonlinear hyperelastic behavior and thus to accurately design and control these actuators. We have created an optimized Neo-Hookean constitutive model of Ecoflex 00-30 silicone rubber. This method is based on the combination of theory and experiments, whose goal is to enhance the usefulness of the model for performance analysis of soft actuators. Dumbbell-shaped specimens were tested in uniaxial tension on a ZQ-990LB testing machine in a controlled environment at 25.4 °C and 57.4% relative humidity (RH). Stretch ratios varied between 1 and 8.6 and tensile speeds up to 500 mm/min were used. Stress–strain curves and fracture behavior were captured by the experiments. The Neo-Hookean model was then fitted and optimized using a global least-squares optimization approach. Two changes were made: piecewise segmentation of the data, and variable weight factors for uniaxial and equibiaxial tensile data. This accuracy was better for each of the stretch ratios. The optimized material parameters yielded curves that were in close agreement to the experimental data—significantly better than fitting using conventional single regime, particularly in each of the segmented ranges. The model breaks the range of deformations into segments, and in each segment it reflects the response of the silicone rubber to the various loadings. The results provide a good theoretical foundation for modeling the mechanics, analyzing the kinematics and developing intelligent control strategies for pneumatic soft actuators. This should help propel their engineering applications in dynamic environments. Full article

A textile-based membraneless microfluidic microalgae–microbial solar cell (μmMSC) was developed for low-cost, flexible, and sustainable power generation. Unlike conventional systems, the proposed device utilizes a textile substrate, enabling mechanical flexibility and simplified fabrication. Microfluidic channels were patterned via screen printing using hydrophobic Ecoflex, and conductive electrodes were fabricated using PEDOT:PSS combined with Ag₂O and carbon nanotubes (MWCNT/SWCNT). At the anode, Synechocystis sp., Bacillus subtilis, and Shewanella oneidensis MR-1 were vertically co-cultured to enhance synergistic bioelectrochemical activity, while Scenedesmus obliquus was employed as a microalgae-based biocathode. Under these conditions, the μmMSC achieved a maximum current density of 144 μA cm⁻² and a peak power density of 17 μW cm⁻². These results demonstrate that the proposed textile-based μmMSC provides a promising platform for flexible bio-solar energy systems, with potential for wearable applications, while offering improved sustainability and scalability compared to conventional rigid device. Full article

Regional anesthesia is vital for modern surgical practices, but accessibility to training is often hampered by the high cost of commercial phantom models. This study aimed to develop and evaluate low-cost, realistic phantom alternatives using Ecoflex, borax-containing polyvinyl alcohol (PVA), and plastisol compositions. The models were evaluated under ultrasound for imaging properties, including needle visibility, tissue resistance, cost, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), axial full width at half maximum (FWHM), and compared to a commercial reference (Blue Phantom). Initial qualitative assessments were performed by three experienced evaluators, and inter-observer agreement demonstrated good to excellent reliability. In addition, a long-term usability assessment was conducted more than one year after phantom preparation, involving 20 participants using a structured Likert scale. A statistically significant difference was observed among materials (Friedman test, p < 0.05), with PVA hydrogel containing 20 g borax and the Blue Phantom demonstrating the highest tissue realism scores, without a significant difference between them. The results showed that plastisol softener and PVA (20 g borax) hydrogel provided excellent needle visibility and tissue resistance and achieved an imaging performance comparable to the commercial model. Notably, CNR and SNR values for these materials approached reference levels, while costs ranged from $0.5 to $2.50 per 100 mL, representing a significant reduction compared to $45 per 100 mL for commercial models. In conclusion, this research confirms that affordable materials such as PVA and plastisol can effectively simulate human tissue for ultrasound-guided training. Furthermore, the findings suggest that PVA-based hydrogels may provide sustained usability over time, offering a practical and accessible solution for enhancing clinical skill acquisition in resource-constrained settings. Full article

This study investigates the relationship between viscosity and manufacturability of two-component silicones in extrusion-based additive manufacturing. A methodology is proposed to adapt commercially available, low-viscosity general-purpose silicones for direct 3D printing using the material extrusion system provided by Lynxter S300X. EcoFlex™ 00-50 silicone was modified through controlled additions of a thixotropic agent (THI-VEX), producing formulations with progressively increased viscosity. After a preliminary qualitative viscosity assessment, formulations were printed using identical process parameters and evaluated through a set of dedicated geometric benchmark specimens targeting critical failure modes, including unsupported thin walls, overhangs, gaps, and slender structures. Print outcomes were assessed via multi-rater visual inspection with inter-rater reliability analysis to ensure consistency. Results reveal a strong correlation between thixotropy and geometric fidelity, identifying the formulation containing 4.0 wt% THI-VEX as optimal under the tested conditions. The study provides practical design and process guidelines for silicone additive manufacturing and highlights the importance of integrated material–process optimization for reliable fabrication of soft, highly deformable materials. Full article

In this study, a material-driven strategy is presented to realize tunable triboelectric–electromagnetic hybrid generators while overcoming the form-factor limitations of conventional magnet-assisted systems. A magneto-dielectric hybrid generator (MDHG) was constructed using a soft magnetized dielectric composite, where NdFeB microparticles were embedded in an Ecoflex matrix and activated by pulse magnetization, allowing a single compliant layer to operate simultaneously as a triboelectric contact medium and a magnetic flux source coupled to a coil. The magnetic filler loading was systematically optimized to elucidate the trade-off between enhanced electromagnetic induction and a non-monotonic triboelectric response governed by dielectric polarization, surface potential, and interfacial energetics. To selectively strengthen the triboelectric branch without sacrificing electromagnetic output, nanoscale BaTiO₃ was introduced as an interstitial dielectric phase to promote polarization-active pathways and suppress screening-driven charge-utilization loss. Under contact–separation operation, the optimized MDHG produced triboelectric outputs up to a V_OC of 400.40 V and I_SC of 56.95 μA, while the electromagnetic branch delivered up to a V_OC of 260.04 mV and I_SC of 0.89 mA, corresponding to 2.87- and 2.62-fold increases in triboelectric V_OC and I_SC over pristine Ecoflex. Finally, the hybrid signatures enabled a wearable smart-skin interface capable of decoupling touch occurrence, intensity, and counter-material identity. Full article

Limb amputations are a growing global challenge. Electrically powered prosthetic hands are heavy, expensive, and battery dependent. Body-powered prostheses offer a simpler and lighter alternative; however, existing designs require high body forces to operate, exhibit poor aesthetics, and have limited dexterity. This study aims to present a design of a hydraulically actuated soft bending finger with a simple and scalable manufacturing process. This is then realised into a five-fingered body-powered prosthetic hand that is lightweight, comfortable, and representative of a human hand. The actuator was formed from two silicone materials of different stiffness (Stiff Smooth-Sil 950 and flexible Ecoflex 00-30) and reinforced with double-helix fibres to generate bending under internal hydraulic pressure. A shoulder-mounted hydraulic system has been designed to convert scapular elevation and protraction into actuator pressure. Finite element analysis and physical tests were performed to examine the bending and blocking force performance of the actuators. The physical actuators achieved bending angles up to 230 degrees at 60 kPa and blocking forces of 5.9 N at 100 kPa. The prosthetic system was able to grasp and hold a 320-g water bottle. The results demonstrate a soft actuator design that provides simple and scalable manufacturing and shows how these actuators can be incorporated into a body-powered prosthesis. This study provides a preliminary demonstration of the feasibility of human-powered prosthetics and necessitates continued research. This work makes progress towards an affordable and functional body-powered prosthetic hand that can improve the lives of transradial amputees. Full article

Wearable robotic devices for rehabilitation and assistive applications face a critical challenge: discomfort induced by prolonged pressure at the human–robot interface. Conventional attachment systems with static straps or rigid cuffs frequently exceed pain tolerance thresholds, limiting clinical acceptance and patient adherence. This study presents a novel dynamic pressure modulation system using thermally activated Twisted and Coiled Artificial Muscles (TCAMs). The system integrates a lightweight lattice structure (0.1 kg) with biocompatible silicone coating incorporating two TCAMs fabricated from silver-coated nylon 6,6 fibers (Shieldex 235/36 × 4 HCB). Electrothermal activation via 2 A constant current induces axial contraction, dynamically regulating circumferential pressure from 0.05 kgf/cm² to 0.50 kgf/cm² within physiological comfort ranges. Experimental validation on a wrist-worn prototype demonstrates precise pressure control, rapid response (5–10 s), and thermal safety through 8 mm Ecoflex insulation. The system enables on-demand interface stiffening during robotic actuation and controlled pressure release during rest periods, significantly enhancing comfort and device tolerability. This approach represents a promising solution for clinically viable wearable robotic devices supporting upper limb rehabilitation and activities of daily living. Full article

Fingerprint authentication systems encounter growing threats from presentation attacks, making strong liveness detection crucial. This work presents a deep learning-based framework integrating EfficientNetB0 with a Squeeze-and-Excitation (SE) attention approach, using transfer learning to enhance feature extraction. The LivDet 2015 dataset, composed of both real and fake fingerprints taken using four optical sensors and spoofs made using PlayDoh, Ecoflex, and Gelatine, is used to train and test the model architecture. Stratified splitting is performed once the images being input have been scaled and normalized to conform to EfficientNetB0’s format. The SE module adaptively improves appropriate features to competently differentiate live from fake inputs. The classification head comprises fully connected layers, dropout, batch normalization, and a sigmoid output. Empirical results exhibit accuracy between 98.50% and 99.50%, with an AUC varying from 0.978 to 0.9995, providing high precision and recall for genuine users, and robust generalization across unseen spoof types. Compared to existing methods like Slim-ResCNN and HyiPAD, the novelty of our model lies in the Squeeze-and-Excitation mechanism, which enhances feature discrimination by adaptively recalibrating the channels of the feature maps, thereby improving the model’s ability to differentiate between live and spoofed fingerprints. This model has practical implications for deployment in real-time biometric systems, including mobile authentication and secure access control, presenting an efficient solution for protecting against sophisticated spoofing methods. Future research will focus on sensor-invariant learning and adaptive thresholds to further enhance resilience against varying spoofing attacks. Full article

This study investigates the acoustic performance of Ecoflex™ 00-35, a highly flexible silicone rubber, for use in soft and adaptable vibration and noise control systems. Under normal conditions, Ecoflex™ 00-35 consists of two components—Part A and Part B—which are mixed and cured at room temperature to form an elastomer. In this study, curing parameters such as the A/B mixing ratio, thinning agent addition, and curing pressure were varied to examine their effects on acoustic behavior. The microstructure of the prepared samples was analyzed using scanning electron microscopy (SEM), while sound absorption properties were measured using impedance tubes. Test results demonstrated that modifying curing parameters, applying vacuum, and incorporating a thinning agent increased the average cell diameter, leading to the fabrication of a moderate sound absorber with a sound absorption coefficient ranging from 0.35 to 0.60 in the low- to mid-frequency ranges. Further enhancement in low-frequency absorption was achieved by applying low pressure for a short duration, allowing cell expansion. In contrast, the addition of a thinning agent significantly improved absorption at higher frequencies. These findings highlight the influence of processing conditions on the acoustic behavior of soft silicone elastomers and provide valuable insights into their structure–property relationships. Ultimately, this study contributes to the development of advanced materials for acoustic damping and noise control applications. Full article

Tire deformation monitoring is a critical requirement for improving vehicle safety, performance, and intelligent transportation systems. However, most existing flexible strain sensors either lack directional sensitivity or have not been validated in real-world driving environments, limiting their practical application in smart tires. In this work, we report the fabrication of a flexible piezoresistive strain sensor based on a porous laser-induced graphene (LIG) network embedded in an Ecoflex elastomer matrix, with integrated directional force recognition. The LIG–Ecoflex sensor exhibits a high gauge factor of 9.7, fast response and recovery times, and stable performance over 10,000 cycles. More importantly, the anisotropic structure of the LIG enables accurate multi-directional stress recognition when combined with a convolutional neural network (CNN), achieving an overall classification accuracy exceeding 98%. To further validate real-world applicability, the sensor was mounted inside passenger car tires and tested under different loads and speeds. The results demonstrate reliable monitoring of tire deformation with clear correlations to load and velocity, confirming robustness under dynamic driving conditions. This study provides a new pathway for the integration of direction-aware, high-performance strain sensors into intelligent tire systems, with broader potential for wearable electronics, vehicle health monitoring, and next-generation Internet of Vehicles applications. Full article

Diabetic foot ulcers (DFUs) represent a critical global health issue, necessitating the development of advanced smart, flexible, and wearable sensors for continuous monitoring that are reimbursable within foot orthotics. This study presents the design and characterization of a pressure sensor implemented into a shoe insole to monitor diabetic wound pressures, emphasizing the need for a high sensitivity, durability under cyclic mechanical loading, and a rapid response time. This investigation focuses on the electrical and mechanical properties of carbon nanotube (CNT) composites utilizing Ecoflex and polydimethylsiloxane (PDMS). Morphological characterization was conducted using Transmission Electron Microscopy (TEM), Laser Confocal Microscopy, and Scanning Electron Microscopy (SEM). The electrical and mechanical properties of the CNT/Ecoflex- and the CNT/PDMS-based sensor composites were then investigated. CNT/Ecoflex was then further evaluated due to its lower variability performance between cycles at the same pressure, as well as its consistently higher capacitance values across all trials in comparison to CNT/PDMS. The CNT/Ecoflex composite sensor showed a high sensitivity (2.38 to 3.40 kPa⁻¹) over a pressure sensing range of 0 to 68.95 kPa. The sensor’s stability was further assessed under applied pressures simulating human weight. A custom insole prototype, incorporating 12 CNT/Ecoflex elastomeric matrix-based sensors (as an example) distributed across the metatarsal heads, midfoot, and heel regions, was developed and characterized. Capacitance measurements, ranging from 0.25 pF to 60 pF, were obtained across N = 3 feasibility trials, demonstrating the sensor’s response to varying pressure conditions linked to different body weights. These results highlight the potential of this flexible insole prototype for precise and real-time plantar surface monitoring, offering an approachable avenue for a challenging diabetic orthotics application. Full article

The current study focuses on the manufacturing and characterization of various forms of Ecoflex and their composites to improve the mechanical properties and surface texture, specifically for use in wearable sensors and electronic skin applications. Various types of Ecoflex elastomers were mixed to form blended composite materials, which could be used to tune the mechanical properties. Experimental and simulation methods were conducted to understand the mechanical behavior and material properties of the manufactured samples under large deformation (1200% strain) by various dynamic loading conditions. Further, the surface conditions of specimens were analyzed and evaluated using scanning electron microscopy and contact angle goniometer. The Yeoh model reasonably predicts the viscoelastic and hysteresis behavior of Ecoflex and its composites in accordance with the experimental data for small and large strain. The surface smoothness and moisture-resistant properties of the material surface were enhanced up to a contact angle of 127° (maximum) by adding x = 15 wt% of surface tension diffusers, with a slight compromise in stretchability. This comprehensive investigation and database of Ecoflex–Ecoflex composite can guide and help researchers in selecting and applying the most appropriate Ecoflex/blended solutions for a specific application, while providing insight into the mechanics of materials of blended materials. Full article