Recent progress in flexible capacitive sensors: Structures and properties

The future intelligent era that will be brought about by 5G technology can be well predicted. For example, the connection between humans and smart wearable devices will become increasingly more intimate. Flexible wearable pressure sensors have received much attention as a part of this process. Nevertheless, there is a lack of complete and detailed discussion on the recent research status of capacitive pressure sensors composed of polymer composites. Therefore, this article will mainly discuss the key concepts, preparation methods and main performance of flexible wearable capacitive sensors. The concept of a processing "toolbox" is used to review the developmental status of the dielectric layer as revealed in highly cited literature from the past five years. The preparation methods are categorized into types of processing: primary and secondary. Using these categories, the preparation methods and structure of the dielectric layer are discussed. Their influence on the final capacitive sensing behavior is also addressed. Recent developments in the electrode layer are also systematically reviewed. Finally, the results of the above discussion are summarized and future development trends are discussed.