Micro-Tactile Sensors for In Vivo Measurements of Elasticity

Abstract

In this chapter, a sensing approach for the measurement of both contact force and elasticity is introduced and discussed. By using the developed method, the elasticity of various objects (e.g., tissue) can be measured by simply touching the targeted object with the sensor. Each developed sensor consists of a pair of contact elements that have different values of stiffness. During contact, the relative deformation of the two sensing components can be used to calculate the Young’s modulus of elasticity. Several prototypes of tactile sensors have been fabricated through various MEMS processes. One of the prototypes developed through a polymer MEMS process has a favorable flexible structure, which enables the sensor to be integrated on end-effectors for robotic or biomedical applications. Finally, the tactile sensor has been attached on a touch probe and tested in a handheld mode. An estimation algorithm for this handheld device, which employs a recursive least squares method with adaptive forgetting factors, has also been developed. Experimental results show that this sensor can differentiate between a variety of rubber specimens and has the potential to provide reliable in vivo measurement of tissue elasticity.