A simple flexible printed capacitive pressure sensor for chronic wound monitoring

Abstract : In this work, we describe the fabrication of a conformable capacitive pressure sensor obtained by inkjet-printing silver electrodes onto polyimide foils subsequently glued face-to-face onto a double-sided tape. The sensor operates for pressures between ca. 1 Pa and 2 kPa. Its response time is 0.25 s. It presents a non-linear response as a function of the capacitance variation with the pressure, namely ΔC/C0 = Pn with n = 0.58. The sensitivity is higher than 0.5 kPa-1 for pressures below 200 Pa, and 0.08 kPa-1 for pressures up to 2 kPa. The sensor is included into a commercial dressing for direct measurements on the body of a volunteer. It is used to monitor how firmly a dressing is glued on the (skin) surface, the main application being the reduction of ischemia risk. It is also used to monitor the movement of the ankle of the patient while walking, and to monitor the pressure exerted on the foot sole when left at rest down on the floor or lifted.