A highly sensitive and wide-range pressure sensor based on orientated and strengthened TPU nanofiber membranes fabricated by a conjugated electrospinning technology

Abstract

Flexible capacitive pressure sensors as one of the crucial sensing components have aroused widespread concern because of their vital role in development of wearable artificial devices, healthcare biomonitoring and human-machine interface. However, there has been a considerable challenge to successfully fabricate them with a tradeoff between high sensitivity and wide sensing range by low-cost and convenient manufacturing methods. Herein, the orientated thermoplastic polyurethane elastomer rubber nanofiber membranes (TPU-O NMs) were prepared via conjugated electrospinning to build a dielectric layer for the flexible capacitive wide-range pressure sensors with high sensitivity. In addition, polyaniline (PANI) was in situ polymerized on the TPU-O NMs as flexible electrodes to maintain the conductive pathway, flexibility, and breathability of the sensors. The TPU@PANI NMs form a bamboo-raft-like microstructure between the aligned fibers under pressure, resulting in a significant increase in sensitivity and working range. Furthermore, the conductive TPU@PANI NMs can be stretched to 1600% without fracture. The assembled sensor has a high sensitivity of 31.73 kPa−1 and a fast response/recovery time of 96 ms. Meantime, it also exhibits a minimum detection limit of 1 Pa, an excellent stability of 10,000 cycles, and a good linearity in a broad working age (1 Pa∼122.5 kPa). Finally, the capacitive pressure sensor was successfully applied for full-range detection of human motions, such as finger bending, joint bending, and even boxing movements. Hence this highly sensitive and wide-range pressure sensor can be a promising candidate for healthcare monitoring, motion recognition, and wearable circuitry in artificial intelligence.

Keywords

• Flexible capacitive pressure sensor
• Conjugated electrospinning
• Nanofiber membrane
• PANI