Abstract
Flexible tactile sensor has been extensively investigated as a key component for emerging electronics applications such as robotics, wearable devices, computer hardware, and security systems. Tactile sensors based on various one-dimensional materials have been widely explored. However, precise control of the direction and distribution of these nanomaterials remains a great challenge, and it has been difficult to scale down the device. Here, we introduce highly sensitive integrated flexible tactile sensors based on uniform phase-change Ge2Sb2Te5 (GST) thin films that can scale device size down, at least, to micrometer range. Significant piezoresistive effect has been observed in GST-based sensors, showing a giant gauge factor of 338. A proof of concept 5 × 5 sensor array functioning as a touch panel has been demonstrated. Also, the flexible GST tactile sensor has been utilized for monitoring of radial artery pulse. In addition to the well-known tunable electrical and optical properties, the piezoresistive GST films provide a versatile platform for the integration of sensing, recording, and displaying functions.
Highlights
Flexible tactile sensors are of paramount importance for the development of various future applications, including flexible touch display,[1] electronic skin,[2,3,4] health monitoring devices,[5,6] and energy harvesting devices.[7,8,9]
1234567890():,; phase changes result from changes in the bonds between atoms, which modify the electronic and optical properties of GST.[32] molecular dynamics simulation.[30,33,41]
Amorphous to strain sensor was prepared by patterning top electrodes with a crystalline phase transition in GST has been realized by applying a gap of 20 μm on top of 100 nm GST layer grown on polyethylene terephthalate (PET)
Summary
Various nanomaterials including organic/inorganic matrix arrays, hybrid composites, and nanowire or nanotube assemblies have been integrated on flexible substrates for development of flexible tactile sensors.[9,21] Despite the potential and high performance of these devices, it is still a great challenge to fabricate a wearable, multiplex tactile sensor array due to their complicated fabrication process and delicate conduction mechanism (percolation, quantum tunneling, etc.). One intrinsic problem with these nanomaterials is the lack of uniformity that makes it difficult to fabricate highly integrated devices on an industrial scale. Most of the sensors based on these nanomaterials can only give a spatial resolution in millimeter range whereas certain applications such as touch screen and fingerprint recognition require spatial resolution down to micrometer range.[2,22,23,24,25]
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