Conductive compliant mechanisms: Geometric tuning of 3D printed flexural sensors

Abstract

• The geometric design of MEX fabricated compliant flexural sensors highly influences the measured signal amplitude. • An increase in relative resistance is seen when concentrating the bend to a smaller section and is proportional to the bending force. • Hysteresis of the measured signal, due to material relaxation, increases with the concentration of the bending area. • The reproduced flexural sensors fabricated via MEX show consistent sensor behavior. Additive manufacturing of thermoplastic conductive polymer composites offers interesting opportunities for customizing compliant flexural sensors. The study aimed to show that additive manufacturing could be used to fabricate flexural sensors for evaluating the effect of sensor geometry on the sensor output. Prior literature has primarily focused on material optimization rather than geometrical design. The results of this paper show that the signal amplitude between geometrically different flexural sensors with the same footprint can increase ∼28 times. In addition, the bending force is found proportional to the signal amplitude. Thus, concentrating the bending to a small section increases the signal amplitude but also increases the effect of material relaxation broadening the hysteresis loop. This study highlights the importance of considering the geometrical design when fine-tuning additive manufactured flexural sensors. In future work, it is paramount to improve reproducibility, signal linearity, and investigate the effects of geometry on other sensor parameters.