Soft Capacitive Pressure Sensor With Enhanced Sensitivity Assisted by ZnO NW Interlayers and Airgap

Abstract

Highly sensitive capacitive pressure sensors with wide detection range are needed for applications such as humanmachine interfaces, electronic skin in robotics, and health monitoring. However, it is challenging to achieve high sensitivity and wide detection range at the same time. Herein, we present an innovative approach to obtain a highly sensitive capacitive pressure sensor by introducing a zinc oxide nanowire (ZnO NW) interlayer at the polydimethylsiloxane (PDMS)/electrodes interface in the conventional metal-insulator-metal architecture. The ZnO NW interlayer significantly enhanced the performance with ~7 times higher sensitivity (from 0.81 %kPa -1 to 5.6452 %kPa -1 at a low-pressure range (0-10 kPa)) with respect to conventional capacitive sensors having PDMS only as the dielectric. The improvement in sensitivity is attributed to the enhanced charge separation and electric dipole generation due to the displacement of Zn + and Ounder applied pressure. Further, the orientation of ZnO NWs and their placement between the electrodes were investigated which includes either vertical or horizontal NWs near the electrodes, placing a third ZnO NW interlayer in the middle of dielectric PDMS and introducing an air gap between the ZnO NWs/electrode. Among various combinations, the introduction of air gap between the electrode and ZnO NW interlayer revealed a significant improvement in the device performance with ~50 times enhancement at a low-pressure range (0-10 kPa) and more than 200 times increase at a high-pressure range (10-200 kPa), in comparison with the conventional PDMS-based pressure sensor.

V2O5 nanowires coated yarn based temperature sensor for smart textiles

“…Flexible and wearable electronics have potential to enhance the quality of human lives by enabling advances in next-generation technologies such as soft robotics, high performance transistors, electronic-skin, interactive objects, energy storage devices, and mobile healthcare etc [1][2][3][4][5][6][7][8][9][10][11]. Among various configurations, the electronic devices in fibre form factors or on textiles could revolutionise the next generation of applications such as mobile healthcare, internet of things etc.…”

Flexible Capacitive Pressure Sensor Based on Microstructured Composite Dielectric Layer for Broad Linear Range Pressure Sensing Applications

“…It is interesting to notice that until now, different sensing mechanisms have been adopted in the literature to develop flexible pressure sensing components, such as piezoresistive [1][2][3], piezoelectric [4], capacitive [5][6][7], and triboelectric [8]. On top of that, during the past decade, numerous studies related to capacitive pressure sensors have been conducted due to their simple structure, facile signal acquisition, and low energy consumption [9]. By taking into account that the human skin has the ability to sense pressure over several orders of magnitude ranging from 10 1 to 10 5 Pa [10], we find that the ideal pressure sensor should be capable of sensing externally applied stress loads with high sensitivity in a wide linearity detection range.…”

Direct ink writing of tunnelling graphite based soft piezoresistive pressure sensors

“…Accurate and repeatable pressure sensors play a significant role in the development of electronic skin (e-Skin) [1][2][3] for applications such as rehabilitation [4,5] robotics [6,7] interactive systems [8,9] and health monitoring [10,11] Among a wide variety of transductions mechanisms explored for pressure sensing, the tunnelling based piezoresistive sensors provide an effective method towards improved tactile recording due to their low cost, high gauge factor, thermal stability and compatibility to the printing technology [12,13]. Furthermore, sensitivity of these sensors can be carefully controlled via engineering the active materials along with their contacts.…”