Exploring Force Sensing With 3D Printing: A Study on Constriction Resistance and Contact Phenomena

This paper examines the contact and constriction resistance phenomena in the context of 3D-printed electronics, with a focus on exploring the use of constriction resistance for force sensing. We design and manufacture a sensor using carbon-black conductive thermoplastic polyurethan (TPU) on a fused deposition modelling (FDM) 3D-printer, and test it using a geometry-based resistive model to fit the data to a number of possible force-resistance relations found in literature. The sensor exhibits low hysteresis between force and resistance, and good sensitivity at low forces, while at high forces it displays consistent contact and stable resistance. We analyse the design methodology and offer recommendations for future sensor design and fitting options, as well as put forward approaches to maximising force sensitivity. Although the exact model derived in this paper is not directly transferable to other sensors, the workflow can serve as a useful guide for future research.