3D printed differential force and position sensor based on a lossy transmission lines

Finished: 2021-03-15

MSc assignment

Recent developments in the field of 3D printing also known as additive manufacturing have helped to fabricate conductive structures, for example, force sensors.

This project aims to design and manufacture a flexible capacitive force sensor using Fused Deposition Modelling (FDM), a technique in 3D printing technology. Usually, 3D printed sensors exhibit anisotropic behavior and have imperfections that affect the electrical properties of the sensors. For example, the resistance of the plates in a capacitive force sensor limits the maximum possible readout frequency. The force sensor is a flexible parallel plate capacitor, printed using a flexible conductive carbon black-filled Thermoplastic Ployutherane (TPU). The force applied to the sensor changes the resistance and capacitance of the sensor, which changes the impedance.

The change in the impedance measured using a multifrequency impedance analyzer. Using this method we expect to be able to measure the total force applied as well as the location where the force is applied, using a low complexity sensor with a minimal number
of connections. The force sensor will be integrated with an exoskeleton and is of the size of the foot. The 3D printed sensor is highly customizable and hence, shows great potential for implementation in prosthetic and robotics applications.

The essay that describes the results from this assignment can be found here.