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A Highly Aligned Nanowire‐Based Strain Sensor for Ultrasensitive Monitoring of Subtle Human Motion

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A Highly Aligned Nanowire‐Based Strain Sensor for Ultrasensitive Monitoring of Subtle Human Motion

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Achieving highly accurate responses to external stimuli during human motion is a considerable challenge for wearable devices. The present study leverages the intrinsically high surface‐to‐volume ratio as well as the mechanical robustness of nanostructures for obtaining highly‐sensitive detection of motion. To do so, highly‐aligned nanowires covering a large area were prepared by capillarity‐based mechanism. The nanowires exhibit a strain sensor with excellent gauge factor (≈35.8), capable of high responses to various subtle external stimuli (≤200 µm deformation). The wearable strain sensor exhibits also a rapid response rate (≈230 ms), mechanical stability (1000 cycles) and reproducibility, low hysteresis (<8.1%), and low power consumption (<35 µW). Moreover, it achieves a gauge factor almost five times that of microwire‐based sensors. The nanowire‐based strain sensor can be used to monitor and discriminate subtle movements of fingers, wrist, and throat swallowing accurately, enabling such movements to be integrated further into a miniaturized analyzer to create a wearable motion monitoring system for mobile healthcare. A highly sensitive flexible strain sensor that is based on large‐area of aligned nanowires is developed. The sensor can be used as a wearable device to accurately detect, discriminate and monitor subtle movements linked with human motion.
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... The resistive strain sensors are fabricated using different substrates and the conducting network material combinations. The substrate materials include PDMS [30,31], Ecoflex [3,32], natural rubber (NR) [33], polyurethane (PU) [34,35], thermoplastic polyurethane (TPU) [36], low-density polyethylene (LDPE) [37], polyethylene terephthalate (PET) [38], styrene-butadiene-styrene (SBS) [39], poly(styrenebutadiene-styrene) (PSBS) [40], and styrene-ethylenebutylene-styrene (SEBS) [41]. Fiber-based materials such as nylon/spandex [42], polyester fabric [43], cotton [44], and cellulose paper [45] are also used to prepare stretchable and conductive textiles. ...
... It was shown that the GF of the nanowire-based strain sensor is nearly five times that of the microwire-based sensors. A low-power bending analyzer is built using a printed circuit board that communicates with a Smartphone Android Application to show the resistance variation on bending and movement [31]. In another similar work, having PEDOT:PSS filled into the microchannels of the PDMS substrate, the sensor exhibits about three times increase in average resistance over a 10% applied strain. ...
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... Therefore, researchers in the field of biomedical engineering and health care monitoring are trying to make further advancements in sensor sensitivity, stretchability, and durability [4]. With top-notch efficiency and accuracy, there are different types of sensors to serve the purpose of "human motion monitoring" that have already been invented, like electro-goniometers [5], optical processing-based sensors [6], nano or micro electrochemical sensors [7]. But on the perspective of cost and size, these intelligent devices are not so attractive. ...
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... These flexible devices are mainly classified into four categories, namely piezoelectricity [6,7], piezoresistivity [8,9], capacitance [10] and triboelectricity [11], according to the various transduction mechanisms. Among them, the flexible resistive-type sensors that can convert mechanical force into readable electrical resistance variation have been commonly researched due to their advantages of low cost, convenient manufacturing techniques and easy signal acquisition [12,13]. ...
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