Development of 3D CNTS interdigitated finger electrodes on flexible polymer for bending strain measurement

This study reports a novel approach to implement the CNTs (carbon nanotubes)-based flexible capacitive strain sensor and the detection of bending strain is demonstrated. The merits of presented design are as follows, (1) employ the aligned CNTs (50μm~100μm in height) as interdigital finger electrodes to increase sensing area and initial capacitance, (2) the 3D CNTs electrodes and electrical routings, and flexible polymer substrate are batch fabricated on Si substrate and polymer molding, and (3) the CNTs-polymer composites as sensing electrodes and electrical routing can avoid the problem of delamination. Preliminary fabrication results demonstrate a flexible capacitive sensor with 50 μm high CNTs interdigital electrodes on PDMS, the tests show its typical capacitance change is several dozens of fF and the gauge factor ranges 4.6~6.5.