Soft Acoustic Waveguides for Strain, Deformation, Localization, and Twist Measurements

A novel type of soft tactile sensor based on polymeric acoustic waveguides is proposed. Ceramic multi-layer piezoelectric transducers generate ultrasonic acoustic wave packets (980kHz) that propagate and can be attenuated, delayed and reflected based on waveguide deformation and length. We detail the sensor design, manufacture and operation and then propose 6 experiments in which we measure the sensor performance. The sensor can detect strain (up to 80%), normal deformation (up to 1mm), simultaneous strain and deformation, compression location (0.5mm interval) and twists (up to 400 axial rotations per meter) and is insensitive to bending (up to 250m
^-1
). This work is the first to propose using soft polymeric waveguides as a tactile element for strain, deformation, localization and twist measurement. This is also the first work to demonstrate decoupled strain and deformation sensing in a single, soft, sensing element. This research aims at introducing an innovative sensing method that can be leveraged toward the creation of simpler and denser multi-modal soft sensors.