All-Nanofibrous Ionic Capacitive Pressure Sensor for Wearable Applications

Abstract

Currently, with the development of electronic skins (e-skins), wearable pressure sensors with low energy consumption and excellent wearability for long-term physiological signal monitoring are urgently desired but remain a challenge. Capacitive-type devices are desirable candidates for wearable applications, but traditional capacitive pressure sensors are limited by low capacitance and sensitivity. In this study, an all-nanofibrous ionic pressure sensor (IPS) is developed, and the formation of an electrical double layer at the electrode/electrolyte contact interface significantly enhances the capacitance and sensing properties. The IPS is fabricated by sandwiching a nanofibrous ionic gel sensing layer between two thermoplastic polyurethane nanofibrous membranes with graphene electrodes. The IPS has a high sensitivity of 217.5 kPa −1 in the pressure range of 0−5 kPa, which is much higher than that of conventional capacitive pressure sensors. Combined with the rapid response and recovery speed (30 and 60 ms), the IPS is suitable for real-time monitoring of multiple physiological signals. Moreover, the nanofiber network endows the IPS with excellent air permeability and heat dissipation, which guarantees comfort during long-term wearing. This work provides a viable strategy to improve the wearability of wearable sensors, which can promote healthcare and human−machine interaction applications.

Recent Advances in Physical Sensors Based on Electrospinning Technology

“…It also had good biological adaptability and permeability. The nanofiber membranes composed of TPU and ion gel ([EMIM] + [TFSI] − ) was used as the sensing layer and sandwiched between two TPU nanofiber membranes with graphene electrodes to obtain a full nanofiber pressure sensor, as shown in Figure a . The sensor had a high sensitivity of 217.5 kPa –1 in the pressure range of 0–5 kPa, which was much higher than the traditional capacitive pressure sensor.…”

Recent progress in flexible pressure sensors based on multiple microstructures: from design to application

“…1,2 In addition, pressure sensors (PSs) have attracted widespread attention as they show great potential for applications in fields such as electronic skin, software robotics, and human health monitoring. 3 Depending on the sensing mechanism, PSs can be classified into four types: piezoresistive, 4-6 capacitive, [7][8][9] piezoelectric, [10][11][12][13] and triboelectric sensors. [14][15][16][17] In addition, the more studied sensors include organic transistor sensors, [18][19][20][21] ion sensors 22,23 and hybrid response pressure sensors.…”

“…Depending on the sensing mechanism, PSs can be classified into four types: piezoresistive, 4–6 capacitive, 7–9 piezoelectric, 10–13 and triboelectric sensors. 14–17 In addition, the more studied sensors include organic transistor sensors, 18–21 ion sensors 22,23 and hybrid response pressure sensors.…”

Conjugated Polymer-Based Nanocomposites for Pressure Sensors

“…Flexible sensors have attracted tremendous attention due to their potential applications in the fields of health monitoring, medical diagnosis, electronic skin (e-skin), and artificial intelligence [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. In recent years, flexible sensors have made great progress in material selection, structure design, and practical application [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ].…”