A forefinger-like tactile sensor for elasticity sensing based on piezoelectric cantilevers

Current researches on tactile sensors are mainly focused on force sensing, but studies on elasticity sensing are very lacking. In this work, a forefinger-like tactile sensor is proposed with the functions of force sensing, contact prediction, and elasticity sensing. The sensor is made of a piezoelectric bimorph cantilever with a strain gauge for deformation monitoring. A cone-shaped tip is fabricated on the cantilever's free end to contact the testing sample. When the sensor approaches to the sample's surface, the bimorph cantilever is excited to vibrate in its flexure mode. Consequently, the vibration amplitude would shift regularly when the tip is close enough to the sample, leading to the contact prediction function. When the tip touches the sample, the sample's elasticity can be derived by tracking the contact resonance frequency of the cantilever-sample system. The functions of the proposed sensor were carefully examined and excellent performances were achieved. The proposed sensor is adaptive and may hold potentials in sample characterization in industry. (C) 2015 Elsevier B.V. All rights reserved.