3D printed flexible capacitive force sensor with a simple micro-controller based readout

This paper describes the development of a proof of principle of a flexible force sensor and the corresponding readout circuit. The flexible force sensor consists of a parallel plate capacitor that is 3D printed using regular and conductive thermoplastic poly-urethane (TPU). The capacitance change due to an applied sinusoidal force is measured using an LCR meter. A proof of principle, using an oscillatory readout circuit consisting of only an operational amplifier and a frequency-counter based on an Arduino Nano, is provided. This indicates the possibility to implement low-cost capacitive sensors into 3D printed objects, which is especially interesting for customised robotic and prosthetic applications.