Highly sensitive integrated flexible tactile sensors with piezoresistive Ge 2 Sb2Te5 thin films

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. By reducing feature size to one micron, flexible tactile sensors with high spatial resolution and sensitivity are demonstrated. A collaborative team led by Nian-Xiang Sun from the Department of Electrical and Computer Engineering at Northeastern University developed integrated flexible tactile sensors and sensor arrays with high sensitivity and spatial resolution. The sensor’s high sensitivity (e.g. gauge factor of 338) is due to developed piezoresistive Ge2Sb2Te5 thin films. To obtain a high spatial resolution above 12,700 pixels per inch, the sensor’s feature size was reduced to one micron. Sun and co-workers demonstrate the applicability of the integrated flexible tactile sensors for next-generation touch display applications through proof-of-concept 5 × 5 sensor arrays and Ge2Sb2Te5 strain sensors with enhanced performance at smaller size.