Special Issue "Wearable Energy Harvesting and Storage Devices"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (31 March 2020).

Special Issue Editor

Prof. Dr. Mehmet C Ozturk
Website
Guest Editor
Department of Electrical & Computer Engineering, Deputy Director, NSF Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST), North Carolina State University, Campus Box 7920, Raleigh, NC 27695-7920, USA
Interests: flexible electronics; thermoelectrics; energy harvesting from the human body; self-powered wearable electronics; Si and SiGe epitaxy; low-resistivity contacts; CMOS

Special Issue Information

Dear Colleagues,

Interest in wearable electronics for continuous, multi-modal health and performance monitoring is rapidly growing. Applications of these wearable systems span a wide spectrum that include wellness monitoring, chronic disease detection and monitoring, implantable electronics, drug adherence and military operations. Future systems must incorporate many sensors in order to achieve a comprehensive assessment of the human condition as well as the environment. In addition, they need to transmit the information wirelessly to a base station, where data processing can take place. As the functionality of these systems increases, so do their energy requirements, which eliminates the use of chemical batteries for long-term, continuous monitoring. To achieve high user compliance, especially among the elderly population, it is also highly undesirable to employ rechargeable batteries. The obvious solution to these challenges is the development of self-powered systems that completely rely on the energy harvested from the human body or the ambient environment. 

A variety of energy harvesting technologies for wearable systems are currently being considered. Examples include thermoelectric generators that harvest body heat, piezoelectric or electromagnetic devices that harvest kinetic energy, and ambient RF harvesting. In many cases, these energy harvesting systems have to operate under less than ideal conditions, which require them to employ state-of-the-art materials and integration technologies to achieve the highest possible efficiency levels. 

Unfortunately, no matter how efficient these harvesters might be, there will be times during the day when they will simply not harvest any appreciable energy. Therefore, it is also essential that these systems have the ability to store the harvested energy so it can be used on demand. The harvested energy can be stored in rechargeable batteries or supercapacitors, which offer a myriad of opportunities for new materials and technologies.

It is also well established that for wearable systems, comfort and aesthetics are key factors for user compliance. These systems often need to make intimate contact to the human body for better signal quality and/or to reduce the parasitic resistances between the device and the skin. These considerations make flexible electronics that can conform to the body a highly desirable avenue for wearables. Consequently, there is a strong interest in developing flexible energy harvesting and storage technologies that can be integrated into wearable systems.

This Special Issue will focus on energy harvesting and storage technologies specifically suitable for wearable systems to monitor both health and the environment. As such, both rigid and flexible technologies are of interest. It is my pleasure to invite you to submit a manuscript for this Special Issue. Full papers, communications, and reviews are all welcome.

Prof. Dr. Mehmet C Ozturk
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Wearable Devices
  • Wearable Electronics
  • Wearables
  • Health Monitoring
  • Energy harvesting
  • Heat Harvesting
  • Motion Harvesting
  • Energy Storage
  • Thermoelectric
  • Photovoltaic
  • Piezoelectric
  • Electromagnetics
  • Rechargeable Batteries
  • Supercapacitors

Published Papers (4 papers)

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Research

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Open AccessArticle
Carbon Dots-Decorated Bi2WO6 in an Inverse Opal Film as a Photoanode for Photoelectrochemical Solar Energy Conversion under Visible-Light Irradiation
Materials 2019, 12(10), 1713; https://doi.org/10.3390/ma12101713 - 27 May 2019
Cited by 1
Abstract
This work focuses on the crystal size dependence of photoactive materials and light absorption enhancement of the addition of carbon dots (CDs). mac-FTO (macroporous fluorine-doped tin oxide) films with an inverse opal structure are exploited to supply enhanced load sites and to induce [...] Read more.
This work focuses on the crystal size dependence of photoactive materials and light absorption enhancement of the addition of carbon dots (CDs). mac-FTO (macroporous fluorine-doped tin oxide) films with an inverse opal structure are exploited to supply enhanced load sites and to induce morphology control for the embedded photoactive materials. The Bi2WO6@mac-FTO photoelectrode is prepared directly inside a mac-FTO film using a simple in situ synthesis method, and the application of CDs to the Bi2WO6@mac-FTO is achieved through an impregnation assembly for the manipulation of light absorption. The surface morphology, chemical composition, light absorption characteristics and photocurrent density of the photoelectrode are analyzed in detail by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (DRS), Energy dispersive X-ray analysis (EDX) and linear sweep voltammetry (LSV). Full article
(This article belongs to the Special Issue Wearable Energy Harvesting and Storage Devices)
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Open AccessFeature PaperArticle
N-Type Bismuth Telluride Nanocomposite Materials Optimization for Thermoelectric Generators in Wearable Applications
Materials 2019, 12(9), 1529; https://doi.org/10.3390/ma12091529 - 10 May 2019
Cited by 5
Abstract
Thermoelectric materials could play a crucial role in the future of wearable electronic devices. They can continuously generate electricity from body heat. For efficient operation in wearable systems, in addition to a high thermoelectric figure of merit, zT, the thermoelectric material must [...] Read more.
Thermoelectric materials could play a crucial role in the future of wearable electronic devices. They can continuously generate electricity from body heat. For efficient operation in wearable systems, in addition to a high thermoelectric figure of merit, zT, the thermoelectric material must have low thermal conductivity and a high Seebeck coefficient. In this study, we successfully synthesized high-performance nanocomposites of n-type Bi2Te2.7Se0.3, optimized especially for body heat harvesting and power generation applications. Different techniques such as dopant optimization, glass inclusion, microwave radiation in a single mode microwave cavity, and sintering conditions were used to optimize the temperature-dependent thermoelectric properties of Bi2Te2.7Se0.3. The effects of these techniques were studied and compared with each other. A room temperature thermal conductivity as low as 0.65 W/mK and high Seebeck coefficient of −297 μV/K were obtained for a wearable application, while maintaining a high thermoelectric figure of merit, zT, of 0.87 and an average zT of 0.82 over the entire temperature range of 25 °C to 225 °C, which makes the material appropriate for a variety of power generation applications. Full article
(This article belongs to the Special Issue Wearable Energy Harvesting and Storage Devices)
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Open AccessArticle
Magnetoelectric Transducer Designs for Use as Wireless Power Receivers in Wearable and Implantable Applications
Materials 2019, 12(3), 512; https://doi.org/10.3390/ma12030512 - 08 Feb 2019
Cited by 1
Abstract
As the size of biomedical implants and wearable devices becomes smaller, the need for methods to deliver power at higher power densities is growing. The most common method to wirelessly deliver power, inductively coupled coils, suffers from poor power density for very small-sized [...] Read more.
As the size of biomedical implants and wearable devices becomes smaller, the need for methods to deliver power at higher power densities is growing. The most common method to wirelessly deliver power, inductively coupled coils, suffers from poor power density for very small-sized receiving coils. An alternative strategy is to transmit power wirelessly to magnetoelectric (ME) or mechano-magnetoelectric (MME) receivers, which can operate efficiently at much smaller sizes for a given frequency. This work studies the effectiveness of ME and MME transducers as wireless power receivers for biomedical implants of very small (<2 mm3) size. The comparative study clearly demonstrates that under existing safety standards, the ME architecture is able to generate a significantly higher power density than the MME architecture. Analytical models for both types of transducers are developed and validated using centimeter scale devices. The Institute of Electrical and Electronics Engineers (IEEE) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) standards were applied to the lumped elements models which were then used to optimize device dimensions within a 2 mm3 volume. An optimized ME device can produce 21.3 mW/mm3 and 31.3 W/mm3 under the IEEE and ICNIRP standards, respectively, which are extremely attractive for a wide range of biomedical implants and wearable devices. Full article
(This article belongs to the Special Issue Wearable Energy Harvesting and Storage Devices)
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Review

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Open AccessReview
A Review on Low-Grade Thermal Energy Harvesting: Materials, Methods and Devices
Materials 2018, 11(8), 1433; https://doi.org/10.3390/ma11081433 - 14 Aug 2018
Cited by 23
Abstract
Combined rejected and naturally available heat constitute an enormous energy resource that remains mostly untapped. Thermal energy harvesting can provide a cost-effective and reliable way to convert available heat into mechanical motion or electricity. This extensive review analyzes the literature covering broad topical [...] Read more.
Combined rejected and naturally available heat constitute an enormous energy resource that remains mostly untapped. Thermal energy harvesting can provide a cost-effective and reliable way to convert available heat into mechanical motion or electricity. This extensive review analyzes the literature covering broad topical areas under solid-state low temperature thermal energy harvesting. These topics include thermoelectricity, pyroelectricity, thermomagneticity, and thermoelasticity. For each topical area, a detailed discussion is provided comprising of basic physics, working principle, performance characteristics, state-of-the-art materials, and current generation devices. Technical advancements reported in the literature are utilized to analyze the performance, identify the challenges, and provide guidance for material and mechanism selection. The review provides a detailed analysis of advantages and disadvantages of each energy harvesting mechanism, which will provide guidance towards designing a hybrid thermal energy harvester that can overcome various limitations of the individual mechanism. Full article
(This article belongs to the Special Issue Wearable Energy Harvesting and Storage Devices)
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