A review of recent progress in flexible capacitance pressure sensors: materials design, printing methods, and applications

Rapid advancements in sensor technology have come about due to the emergence of new technologies such as IoT and intelligent homes. In this scenario, smart sensors are becoming more and more necessary. Piezoelectrical or electromechanical principle-based flexible pressure sensors are widely researched due to their wide spread applications in robotics, electronic skin, and healthcare fields. Among the pressure sensors, capacitance pressure sensor (CPS) shows advantageous properties like high dynamic response, low power consumption, wireless data reader, easy sensor integration into data readout circuits, short-term over pressure tolerance, low temperature coefficient, etc. Here, we have attempted to provide readers with an overview of capacitance sensors, their main architectural designs, contact and non-contact printing processes, different techniques to increase the sensitivity of CPS, and—above all—their applications. From the extensive investigation, we found that inkjet, screen, and gravure printing are the preferred printing techniques for fabricating flexible CPS. Wearable electronics has been a booming field in recent years, and the latest developments in the field of flexible capacitance pressure sensor can complement this. A detailed discussion is held regarding the latest advancements in capacitance pressure sensor that can be applied to various real-time scenarios like e-skin, robotics, and vital sign monitoring.