Recent Progress on Flexible Capacitive Pressure Sensors: From Design and Materials to Applications

Abstract

For decades, the revolution in design and fabrication methodology of flexible capacitive pressure sensors using various inorganic/organic materials has significantly enhanced the field of flexible and wearable electronics with a wide range of applications in aerospace, automobiles, marine environment, robotics, healthcare, and consumer/portable electronics. Mathematical modelling, finite element simulations, and unique fabrication strategies are utilized to fabricate diverse shapes of diaphragms, shells, and cantilevers which function in normal, touch, or double touch modes, operation principles inspired from microelectromechanical systems (MEMS) based capacitive pressure sensing techniques. The capacitive pressure sensing technique detects changes in capacitance due to the deformation/deflection of a pressure sensitive mechanical element that alters the separation gap of the capacitor. Due to advancement in state‐of‐the‐art fabrication technologies, the performance and properties of capacitive pressure sensors are enhanced. In this review paper, recent progress in flexible capacitive pressure sensing techniques in terms of design, materials, and fabrication strategies is reported. The mechanics and fabrication steps of paper‐based low‐cost MEMS/flexible devices are also broadly reported. Lastly, the applications of flexible capacitive pressure sensors, challenges, and future perspectives are discussed.

Two-dimensional van der Waals thin film transistors as active matrix for spatially resolved pressure sensing

“…As expected, the 2D vdW-TFTs based pressure sensor exhibits a rapid response (~ 50 ms) (Fig. S5 in the ESM), which is comparable to most microstructured piezoresistive [54,58] and capacitive [57] ones (tens of milliseconds), and much faster than the traditional unstructured one (several seconds) [6].…”

“…The pressure sensing range of these sensors is beyond that of the microstructured sensors with conductive surface coats (typically limited in the pressure range of 0−10 kPa) [52,54]. The sensitivity in the low-pressure regime is comparable to that of the highest reported in piezoresistive ones (56−133.1 kPa −1 in less than 30 Pa) [56], and greatly higher than those of most common capacitive ones (less than several kPa −1 ) [6,7,57]. Moreover, the minimal hysteresis of 2D vdW-TFTs could contribute the integrated pressure sensor to maintain the excellent sensing performances of the micro-pyramidal rubber electrodes, such as the relatively low hysteresis and fast response.…”

New Directions in Sensor Research: A Bibliometric Analysis for Detecting Emerging Research Fields and New Technological Trajectories

“…Park et al, 2021). Results also suggest that pressure sensing is a main technological characteristic of wearable sensors (Lee et al, 2020;Mishra et al, 2021). However, wearable sensors are still facing several challenges.…”

Solar Powered Small Unmanned Aerial Vehicles: A Review

“…The solar powered SUAVs are hybrid‐powered systems that consist of multiple components such as electric motor, speed controller, switching circuits, pressure sensors, actuators batteries and solar cells. [ 9,102,124–127 ] The miniaturization of SUAVs requires the miniaturization of every component of the vehicle however the major components of SUAVs are the solar cells, batteries and electronics parts. The large‐sized solar powered UAVs have been developed since a longer time, however, the advancement in SUAVs is gaining huge attention in agricultural, surveillance, remote sensing, and infrastructure inspection applications due to their various advantages such as lightweight and small size.…”