Miniature Compliant Grippers With Vision-Based Force Sensing

Abstract

This paper is concerned with grasping biological cells in aqueous medium with miniature grippers that can also help estimate forces using vision-based displacement measurement and computation. We present the design, fabrication, and testing of three single-piece, compliant miniature grippers with parallel and angular jaw motions. Two grippers were designed using experience and intuition, while the third one was designed using topology optimization with implicit manufacturing constraints. These grippers were fabricated using different manufacturing techniques using spring steel and polydimethylsiloxane (PDMS). The grippers also serve the purpose of a force sensor. Toward this, we present a vision-based force-sensing technique by solving Cauchy's problem in elasticity using an improved algorithm. We validated this technique at the macroscale, where there was an independent method to estimate the force. In this study, the gripper was used to hold a yeast ball and a zebrafish egg cell of less than 1 mm in diameter. The forces involved were estimated to be about 30 and 10 mN for the yeast ball and the zebrafish egg cell, respectively.Index Terms-Cauchy's problem, mesoscale manufacturing, microgripper, topology optimization, vision-based force sensing.

Measurement of Deformation and Force for Microcantilevers Based on Feature Point Matching and Digital Image Correlation

“…(19) and (20). An important issue in the displacement estimation is the determination of the origin of the microcantilever for cantilever deflection.…”

“…To detect the deformation of normal microsamples, markers (20)(21)(22)(23)(24) are widely used to calculate the displacement information. Markers may be dark paints that are sprayed to the microspecimen, (20,21) or array spots (22) of different shapes obtained by milling at the end of a microcantilever, or microarrays (23) indented into the surface of a thin film, or even gold lines (24) deposited on silicon specimens for strain measurement. Besides the high cost for fabricating local features with high precision on the specimens, there are two additional issues that arise in the utilization of the manually specialized "marker" method.…”

Design of compliant parallel grippers using the position space concept for manipulating sub-millimeter objects

“…However, compliant mechanism based designs, transferring force or displacement through the elastic deformation of one or more flexible members within the structure (i.e., jointless), can overcome the above problems. Due to their advantages of reducing the number of parts (thereby raising the system reliability), reducing the assembly and fabrication cost, and increasing the system performance, such grippers have been successfully used in the applications of precision engineering, biomedical devices and MEMS [3][4][5][6][7][8][9][10][11].…”

“…Topology optimization based methods have also been employed to design CPGs [11]. Displacement amplification mechanisms are usually involved in these designs.…”

Vision-Based Haptic Feedback for Remote Micromanipulation in–SEM Environment

“…However, their integration into the dedicated tools is complex, and greatly increases the difficulty of their design and their conception. Vision is, thus, a promising solution to compensate for this lack of sensing (Chawda and O'Malley 2011;Greminger and Nelson 2004;Pawashe and Sitti 2006;Reddy et al 2010).…”