A high-resolution and low-cost mesoscale tactile force sensor based on mode-localization effect and fabricated using rapid prototyping

Abstract

This paper presents a novel design of a high resolution and low-cost tactile force sensor, based on the concept of mode-localization in two weakly coupled resonators (WCRs). The sensor is fabricated at mesoscale by utilizing rapid prototyping techniques. The two WCRs in the sensor are operated at resonance by using an electrostatic actuation. Change in the oscillation amplitude ratios and resonant frequency shift, corresponding to an input force is utilized as an output metric for the measurement of force. The application of an applied force on the WCRs induced electrostatic strain, which acted as a negative stiffness perturbation. The outer body of sensor is manufactured using a soft silicone elastomer and shaped using molds based on laser cutting technique. The proposed tactile force sensor is analyzed numerically through finite-element-method (FEM) based simulations. For the testing of tactile force sensor, an actuation and sensing electronics scheme is developed. The experimental results revealed that the sensor is capable of measuring input force up to 20 mN with a relative amplitude ratio (AR) and resonant frequency shift based sensitivity of 27040 ppm/mN and 3553 ppm/mN respectively. The experimentally evaluated resolution for the sensor is 7.3 µN. The sensor shows the stability in response to the thermal variations and low-frequency vibrational environments.