Microengineering Pressure Sensor Active Layers for Improved Performance

Abstract

Pressure sensors play an integral role in a wide range of applications, such as soft robotics and health monitoring. In order to meet this demand, many groups microengineer the active layer-the layer that deforms under pressure and dictates changes in the output signal-of capacitive, resistive/piezoresistive, piezoelectric, and triboelectric pressure sensors in order to improve sensor performance. Geometric microengineering of the active layer has been shown to improve performance parameters such as sensitivity, dynamic range, limit of detection, and response and relaxation times. There are a wide range of implemented designs, including microdomes, micropyramids, lines or microridges, papillae, microspheres, micropores, and microcylinders, each offering different advantages for a particular application. It is important to compare the techniques by which the microengineered active layers are designed and fabricated as they may provide additional insights on compatibility and sensing range limits. To evaluate each fabrication method, it is critical to take into account the active layer uniformity, ease of fabrication, shape and size versatility and tunability, and scalability of both the device and the fabrication process. By better understanding how microengineering techniques and design compares, pressure sensors can be targetedly designed and implemented.

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

“…Micro‐pillars, micro‐bumps, and micro‐structures as dielectric material have been widely explored for more than a decade in the design of highly sensitive flexible capacitive pressure sensors. [ 103,104 ] Micro‐arrays are developed by casting PDMS on silicon mold and then ITO/PET thin film that acts as electrodes is laminated on the PDMS [ Figure a]. [ 105 ] After peeling off the ITO/PET thin film from the silicon mold, the PDMS micro‐arrays are formed, as shown in the scanning electron microscope (SEM) image [Figure 7b].…”

Flexible Fringe Effect Capacitive Sensors with Simultaneous High‐Performance Contact and Non‐Contact Sensing Capabilities

“…Highly sensitive pressure sensors have been obtained by microstructuring the dielectric layer, which causes compression to also displace air within that layer. [ 33,41–43,45–52 ] As air has a lower dielectric constant than the dielectric material, this change causes an increase in the overall effective dielectric constant of the layer, which further increases the change in capacitance upon compression. [ 43,46 ]…”

Amalgamation‐Assisted Control of Profile of Liquid Metal for the Fabrication of Microfluidic Mixer and Wearable Pressure Sensor

“…The sensing performance of the sensor is projected to be affected by the surface area and deformation of the microstructure. [39][40][41][42] Changes in resistance upon the application of a repeated pressure of 88.89 kPa were detected. It can be clearly seen in Figure 5c that the relative change in resistance is almost the same (over 1000 cycles were tested in the experiments), which demonstrated high durability and stability.…”