Flexible 3-axes capacitive pressure sensor array for medical applications

Wearable pressure sensors arrays are required for various monitoring purposes in medicine. To meet with the wanted specifications, capacitive sensors arrays realized on highly flexible substrates have been proven to be good candidates to let non-invasive as well as accurate stress measurements to be carried out. Since single-axis pressure measurements may be found incomplete in some applications, capacitive arrays featuring 3-axes pressure sensing capabilities are considered in this study. A sensor array prototype featuring 25 element 3-axes micro-sensors are designed. They are realized on a flexible substrate (Kapton) using PDMS as a deformable dielectric material, by means of an original transfer of film technique. The principle of operation of such sensors is based on the capacitance change of capacitive sensors with the deformation of the dielectric layer separating the sensor electrodes, under an applied stress. Finite element computations are carried to foresee and optimize the sensors sensitivity to stress. Electromechanical tests are carried out on the realized sensors for validation purposes.