Direct writing on paper of foldable capacitive touch pads with silver nanowire inks.
19 Nov 2014-ACS Applied Materials & Interfaces (American Chemical Society)-Vol. 6, Iss: 23, pp 21721-21729
TL;DR: A simplified model to predict touch pad capacitance variation ranges with differing touch conditions was developed, with good agreement against experimental results, and holds promise for numerous commercial applications including low-cost portable devices where ultrathin and lightweight features, coupled with reliable bending stability are desirable.
Abstract: Paper-based capacitive touch pads can be fabricated utilizing high-concentration silver nanowire inks needle-printed directly onto paper substrates through a 2D programmable platform. Post deposition, silver nanowire tracks can be photonically sintered using a camera flash to reduce sheet resistance similar to thermal sintering approaches. Touch pad sensors on a variety of paper substrates can be achieved with optimized silver nanowire tracks. Rolling and folding trials, which yielded only modest changes in capacitance and no loss of function, coupled with touch pad functionality on curved surfaces, suggest sufficient flexibility and durability for paper substrate touch pads to be used in diverse applications. A simplified model to predict touch pad capacitance variation ranges with differing touch conditions was developed, with good agreement against experimental results. Such paper-based touch pads have the advantage of simple structure, easy fabrication, and fast sintering, which holds promise for numerous commercial applications including low-cost portable devices where ultrathin and lightweight features, coupled with reliable bending stability are desirable.
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TL;DR: This Review summarizes the recent progress of flexible sensing electronics for their use in wearable/attachable health monitoring systems, and presents an overview of different materials and configurations for flexible sensors, including piezo-resistive, piezos-electrical, capacitive, and field effect transistor based devices.
Abstract: Wearable or attachable health monitoring smart systems are considered to be the next generation of personal portable devices for remote medicine practices. Smart flexible sensing electronics are components crucial in endowing health monitoring systems with the capability of real-time tracking of physiological signals. These signals are closely associated with body conditions, such as heart rate, wrist pulse, body temperature, blood/intraocular pressure and blood/sweat bio-information. Monitoring such physiological signals provides a convenient and non-invasive way for disease diagnoses and health assessments. This Review summarizes the recent progress of flexible sensing electronics for their use in wearable/attachable health monitoring systems. Meanwhile, we present an overview of different materials and configurations for flexible sensors, including piezo-resistive, piezo-electrical, capacitive, and field effect transistor based devices, and analyze the working principles in monitoring physiological signals. In addition, the future perspectives of wearable healthcare systems and the technical demands on their commercialization are briefly discussed.
708 citations
TL;DR: To imitate tactile sensing via e‐skins, flexible and stretchable pressure sensor arrays are constructed based on different transduction mechanisms and structural designs that can map pressure with high resolution and rapid response beyond that of human perception.
Abstract: The skin is the largest organ of the human body and can sense pressure, temperature, and other complex environmental stimuli or conditions. The mimicry of human skin's sensory ability via electronics is a topic of innovative research that could find broad applications in robotics, artificial intelligence, and human-machine interfaces, all of which promote the development of electronic skin (e-skin). To imitate tactile sensing via e-skins, flexible and stretchable pressure sensor arrays are constructed based on different transduction mechanisms and structural designs. These arrays can map pressure with high resolution and rapid response beyond that of human perception. Multi-modal force sensing, temperature, and humidity detection, as well as self-healing abilities are also exploited for multi-functional e-skins. Other recent progress in this field includes the integration with high-density flexible circuits for signal processing, the combination with wireless technology for convenient sensing and energy/data transfer, and the development of self-powered e-skins. Future opportunities lie in the fabrication of highly intelligent e-skins that can sense and respond to variations in the external environment. The rapidly increasing innovations in this area will be important to the scientific community and to the future of human life.
679 citations
265 citations
TL;DR: This review attempts to summarize the recent progress in flexible and stretchable sensors, concerning the detected health indicators, sensing mechanisms, functional materials, fabrication strategies, basic and desired features.
Abstract: Wearable health monitoring systems have gained considerable interest in recent years owing to their tremendous promise for personal portable health watching and remote medical practices. The sensors with excellent flexibility and stretchability are crucial components that can provide health monitoring systems with the capability of continuously tracking physiological signals of human body without conspicuous uncomfortableness and invasiveness. The signals acquired by these sensors, such as body motion, heart rate, breath, skin temperature and metabolism parameter, are closely associated with personal health conditions. This review attempts to summarize the recent progress in flexible and stretchable sensors, concerning the detected health indicators, sensing mechanisms, functional materials, fabrication strategies, basic and desired features. The potential challenges and future perspectives of wearable health monitoring system are also briefly discussed.
255 citations
Cites methods from "Direct writing on paper of foldable..."
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TL;DR: A simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires, and it has been possible to achieve a maximum sensitivity of 5.54 kPa(-1).
Abstract: The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics In these advanced applications, high sensing capability is an essential feature for high performance Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production In the present study a simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires By increasing the relative permittivity, er, of the composite interlayer induced by compression at high nanowire concentration, it has been possible to achieve a maximum sensitivity of 554 kPa−1 The improvement in sensitivity did not sacrifice or undermine the other features of the sensor Thanks to the silver nanowire electrodes, the sensor is flexible and stable after 200 cycles at a bending radius of 2 mm, and exhibits outstanding reproducibility without hysteresis under similar pressure pulses The sensor has been readily integrated onto an adhesive bandage and has been successful in detecting human movements In addition to measuring pressure in direct contact, non-contact pressures such as air flow can also be detected
238 citations
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TL;DR: Transparent, conducting spray-deposited films of single-walled carbon nanotubes are reported that can be rendered stretchable by applying strain along each axis, and then releasing this strain.
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TL;DR: Flexible, capacitive pressure sensors with unprecedented sensitivity and very short response times that can be inexpensively fabricated over large areas by microstructuring of thin films of the biocompatible elastomer polydimethylsiloxane are demonstrated.
Abstract: The development of an electronic skin is critical to the realization of artificial intelligence that comes into direct contact with humans, and to biomedical applications such as prosthetic skin. To mimic the tactile sensing properties of natural skin, large arrays of pixel pressure sensors on a flexible and stretchable substrate are required. We demonstrate flexible, capacitive pressure sensors with unprecedented sensitivity and very short response times that can be inexpensively fabricated over large areas by microstructuring of thin films of the biocompatible elastomer polydimethylsiloxane. The pressure sensitivity of the microstructured films far surpassed that exhibited by unstructured elastomeric films of similar thickness, and is tunable by using different microstructures. The microstructured films were integrated into organic field-effect transistors as the dielectric layer, forming a new type of active sensor device with similarly excellent sensitivity and response times.
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TL;DR: In this article, the authors presented flexible organic solar cells that are less than 2 μm thick, have very low specific weight and maintain their photovoltaic performance under repeated mechanical deformation.
Abstract: Organic solar cells are promising for technological applications, as they are lightweight and mechanically robust. This study presents flexible organic solar cells that are less than 2 μm thick, have very low specific weight and maintain their photovoltaic performance under repeated mechanical deformation.
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