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- 2019
- Topological change
- Multi-hop routing
- low latency
- Wearable Wireless Sensor Network
- wearable devices
- Communication Engineering
- Shenyang Ligong University
- Northeastern University
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Heating Rate-Controlled Thermal Exfoliation for Foldable Graphene Sponge
摘要： Foldable supercapacitors are desired for the next generation of wearable electronics. In this study, highly foldable graphene sponges with a honeycomb structure are prepared at 300 °C using the convenient thermal exfoliation process. A slow heating rate (5?10 °C·min?1) around 200 °C and an external con?nement force are critical to a favorable exfoliation degree and uniform thickness of the graphene sponges. After being annealed at 1050 °C for 1 h, the conductivity of the graphene sponge has been improved from 2700 to 6900 S·m?1 without degrading its ?exibility. The capacitance of the annealed graphene sponge has been measured in an aqueous electrolyte solution of 1 M Na2SO4. Its best capacitance is 138.74 F·g?1, and it reduces by 3.6% at a half-fold state and by 8.9% at a quarter-fold state.
关键词： wearable electronics,Foldable supercapacitors,honeycomb structure,thermal exfoliation,graphene sponges
更新于2025-09-19 17:13:59
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A wearable helical organic–inorganic photodetector with thermoelectric generators as the power source
摘要： A self-powering feature is particularly appealing for wearable electronic devices when facing the challenges of energy and environmental crises. Photodetectors (PDs), as promising candidates for health and environment monitoring, are urgently desired to meet the requirements of being wearable and powerless. Unlike conventional photovoltaic-type PDs, we have come up with a novel approach to make a self-powered wearable PD, which involves connecting PDs with thermoelectric generators (TEGs) in series on the surface of a three-dimensional helical polymer substrate. The wearable system is light-weight, flexible and breathable. More importantly, compared with photovoltaic-type self-powered PDs, wearable PDs powered by TEGs will work as a system whose output signal can be greatly amplified by the temperature difference between the human body and the environment in winter when UV intensity is relatively low.
关键词： UV intensity,thermoelectric generators,self-powered,wearable electronic devices,photodetectors
更新于2025-09-16 10:30:52
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Mechanically controlled reversible photoluminescence response in all-inorganic flexible transparent ferroelectric/mica heterostructures
摘要： The ability to reversibly control the luminescent properties of functional materials with diverse external stimuli, such as an electric ?eld, strain, and temperature, is crucial for designing high-performance optical devices. Here, we demonstrate that a purely mechanical strain in a ?exible mica substrate triggered by bending can be used to dramatically modify the photoluminescence response of a Pr-doped Ba0.85Ca0.15Ti0.9Zr0.1O3 epitaxial thin ?lm in a stable and repeatable manner with a large gauge factor of up to 6853. The strong dependence of the photoluminescence performance on the mechanical bending arises from strain-induced variations in the lattice symmetry of the host ?lm and the local crystal ?eld around the Pr3+. In particular, because of the nature of mica, the ?lm structure exhibits excellent antifatigue characteristics after 104 bending cycles as well as high optical transparency in the range of 450–780 nm. This study provides a viable route for exploring the correlation between structural symmetry and photoluminescence in ferroelectric thin-?lm systems and offers new possibilities for developing all-inorganic, recon?gurable, transparent and ?exible light sources, photodetectors, and wearable sensors.
关键词： ferroelectric,photoluminescence,wearable sensors,mica,flexible,transparent
更新于2025-09-16 10:30:52
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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - A wearable phototherapy device utilizing micro-LEDs
摘要： A conformable device for wearable phototherapy applications is presented. The device consists of a 1mm thick elastomeric membrane edge-lit by specially fabricated micro-sized LEDs. Nanoparticle based scattering films are utilized to extract light and a uniform emission of 15μW/cm2 is reported over an area of 2cm2.
关键词： micro-LEDs,elastomeric membrane,light extraction,wearable phototherapy,uniform emission
更新于2025-09-16 10:30:52
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Pulse Oximetry Using Organic Optoelectronics under Ambient Light
摘要： Light absorption in oxygenated and deoxygenated blood varies appreciably over the visible and near-infrared spectrum. Pulse oximeters use two distinct wavelengths of light to measure oxygen saturation SpO2 of blood. Currently, light-emitting diodes (LEDs) are used in oximeters, which need additional components to drive them and negatively impact the overall size of the sensor. In this work, an ambient light oximeter (ALO) is demonstrated, which can measure photoplethysmography signals and SpO2 using various kinds of ambient light, avoiding the use of LEDs. Spectral filters are combined with organic photodiodes to create the ALO with sensitivity peaks at green (525 nm), red (610 nm), and near-infrared (740 nm) wavelengths. Finally, the wearable ALO is used to measure photoplethysmography signals and SpO2 on the index finger in different indoor and outdoor lighting conditions and the measurements are validated with commercial pulse oximeters under normal and ischemic conditions.
关键词： photoplethysmography,organic photodiodes,oximeters,flexible electronics,wearable sensors
更新于2025-09-16 10:30:52
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Screen Printed Dye-Sensitized Solar Cells (DSSCs) on Woven Polyester Cotton Fabric for Wearable Energy Harvesting Applications
摘要： Recently, the demand for lightweight, flexible and wearable dye-sensitized solar cells has been increased rapidly. One driver for this is to meet the challenge of supplying power in e-textiles applications. Integrating this functionality in the textile will result in an improved feel of the fabric compared to the current approach of the integration of conventional plastic solar patches. A low temperature processed TiO2 paste was used in this work to develop a fabrication method based on screen printing and spray coating to obtain photovoltaic textiles. The fabrication method used is low temperature and is compatible with Kapton and standard woven 65/35 polyester cotton fabrics. Comparing to the latest literatures, [1-3] our results show an improved PV efficiency of 7.03% and 2.78% on Kapton and fabric respectively when using a platinum coated fluorine tin oxide (FTO) glass as the top electrode.
关键词： wearable solar cells,smart fabrics and printed electronics,textile solar cells,wearable technology,dye sensitised solar cells (DSSCs)
更新于2025-09-12 10:27:22
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Transparent multispectral photodetectors mimicking the human visual system
摘要： Compact and lightweight photodetection elements play a critical role in the newly emerging augmented reality, wearable and sensing technologies. In these technologies, devices are preferred to be transparent to form an optical interface between a viewer and the outside world. For this reason, it is of great value to create detection platforms that are imperceptible to the human eye directly onto transparent substrates. Semiconductor nanowires (NWs) make ideal photodetectors as their optical resonances enable parsing of the multi-dimensional information carried by light. Unfortunately, these optical resonances also give rise to strong, undesired light scattering. In this work, we illustrate how a new optical resonance arising from the radiative coupling between arrayed silicon NWs can be harnessed to remove reflections from dielectric interfaces while affording spectro-polarimetric detection. The demonstrated transparent photodetector concept opens up promising platforms for transparent substrates as the base for opto-electronic devices and in situ optical measurement systems.
关键词： augmented reality,wearable technologies,transparent photodetectors,silicon nanowires,spectro-polarimetric detection
更新于2025-09-12 10:27:22
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Morphologically modulated laser-patterned reduced graphene oxide strain sensors for human fatigue recognition
摘要： Laser heating provides an effective method to produce thermally reduced graphene oxide (rGO), it can also pattern the designed layout on the surface of graphene oxide (GO) during the reduction process. In this work, we demonstrated a flexible strain sensor based on the morphologically modulated laser-patterned reduced graphene oxide (LPG) film with a one-step process. Compared with the strain sensor using flat patterned rGO (0-1.2%) and curved-grid patterned rGO (CGPG) (0-4.1%), the strain sensor based on rectangular-grid patterned rGO (RGPG) have highest gauge factor (GF), up to 133 under 2.7% of physical deformation. Meanwhile, the RGPG strain sensors exhibit extraordinary linearity in a relatively large range of deformation (0-2.7%) and excellent endurance for over 1000 stretching-releasing circles. The RGPG strain sensor was used to monitor human fatigue. By analyzing eye blinking frequency and duration, it is possible to evaluate the fatigue level. We anticipate that the RGPG based strain sensor, prepared via a relatively simple and cost-effective process, may open up a broad spectrum of practical applications, such as driver fatigue evaluation and smart monitoring of human body movements.
关键词： wearable electronics,laser patterning,fatigue evaluation,flexible strain sensor,reduced graphene oxide
更新于2025-09-12 10:27:22
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Sandwich-structure transferable free-form OLEDs for wearable and disposable skin wound photomedicine
摘要： Free-form optoelectronic devices can provide hyper-connectivity over space and time. However, most conformable optoelectronic devices can only be fabricated on flat polymeric materials using low-temperature processes, limiting their application and forms. This paper presents free-form optoelectronic devices that are not dependent on the shape or material. For medical applications, the transferable OLED (10 μm) is formed in a sandwich structure with an ultra-thin transferable barrier (4.8 μm). The results showed that the fabricated sandwich-structure transferable OLED (STOLED) exhibit the same high-efficiency performance on cylindrical-shaped materials and on materials such as textile and paper. Because the neutral axis is freely adjustable using the sandwich structure, the textile-based OLED achieved both folding reliability and washing reliability, as well as a long operating life (>150 h). When keratinocytes were irradiated with red STOLED light, cell proliferation and cell migration increased by 26 and 32%, respectively. In the skin equivalent model, the epidermis thickness was increased by 39%; additionally, in organ culture, not only was the skin area increased by 14%, but also, re-epithelialization was highly induced. Based on the results, the STOLED is expected to be applicable in various wearable and disposable photomedical devices.
关键词： Keratinocytes,Wearable photomedicine,Skin wound healing,Cell migration,Epidermis thickness,Re-epithelialization,Free-form optoelectronic devices,Sandwich-structure transferable OLED,Cell proliferation
更新于2025-09-12 10:27:22
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Optimized Process of Fully Spray-Coated Organic Solar Cells on Woven Polyester Cotton Fabrics
摘要： This paper presents the novel use of spray coating to fabricate organic solar cells on fabrics for wearable energy harvesting applications and optimises photovoltaic efficiency. A fully spray coated photovoltaic (PV) device fabricated on fabric has been successfully demonstrated with comparable power conversion efficiency to glass based counterparts. All the PV devices are characterised under AM 1.5 (100mW/cm2) irradiation using an ABET solar simulator. Device morphologies are examined by scanning electron microscopy (SEM). The aim of this study is to develop and optimise a method to obtain reproducible photovoltaic textiles using a fully spray coating processing at low temperature (<150 oC) on a standard 65/35 polyester cotton fabric. The main challenge when spray coating solar cells of less than a few micron thickness is the surface roughness of the polyester cotton fabric which is of the order of 150 μm. We report a maximum optimised efficiency of 2.7% achieved on a glass substrate and 0.02% on woven fabrics, respectively. This approach is suitable for the low cost integration of PV devices into clothing and other decorative textiles.
关键词： Organic solar cells,textile solar cells,wearable and flexible solar cells
更新于2025-09-12 10:27:22