Capacitive Interdigital Sensors for Flexible Enclosures and Wearables

Recent applications related to flexible deployable enclosures for surgery and health care and to wearables may make use of capacitive sensors for monitoring the inflation state of the enclosure, the movements of the human body, and the detection of movements induced by respiration and heart activity (ballistocardiography). We propose the use of flexible, interdigital capacitive sensors in portable enclosures for medical applications, analyze the principles of operation of several versions of such sensors, and provide a theoretical foundation to their design and use, including limitations and errors. The paper also contributes to the analytic description of operation of flexible interdigital sensors, a topic not fully examined previously in the literature.