Hexsil tweezers for teleoperated micro-assembly

Abstract

This paper describes essential components of a prototype system for teleoperated microassembly. High aspect ratio molded polysilicon (hexsil) [ 11 tweezers with integrated in-situ phosphorous doped thermal expansion actuator beams and piezoresistive polysilicon strain gages for tactile feedback are described. The tweezers are normally closed, and require 75 mW to open 35 pm. Piezoresistor performance remains to be measured. Metal lines on surface polysilicon flexible electrical interconnects bridge between rotating rigid hexsil beams. Surface polysilicon tweezer tips provide compliance suitable for force-controlled micromanipulation. The task demonstrated is the pick and placement of a 1 pm x 4 pm x 40 pm peg in a 4 pm x 4 pm hole.The test parts used were surface micromachined SiO, and polysilicon beams held in organized arrays on the silicon wafer by break-away photoresist tethers.

Microstructure to substrate self-assembly using capillary forces

“…In addition, surface forces must be carefully controlled to prevent unwanted adhesion of microscopic parts to each other or tool surfaces [2]. For these reasons, noncontact, parallel assembly techniques in which a large number of components may be assembled simultaneously with microscale precision are being developed.…”

Development of a novel flexure-based microgripper for high precision micro-object manipulation

“…It was found from the diverse micrograsping models in literature that researchers have predominantly emphasized on three major components during model development namely novel microfabrication techniques [9,10], new actuation methodologies [11][12][13] and manipulation of different materials [14][15][16] of smart structures have advanced the grasping technologies and enable compact, highly compliant, and monolithic mechanism to be realized. The fabrication techniques such as Electro Discharge Machining (EDM), LIGA, surface, bulk and laser micromachining, and photo lithography have paved a decisive breakthrough to the persisting constraints in micrograsping methodology particularly associated with the object-gripper compatibility, surface to surface interaction between the object and the gripper's jaws and nonlinearity during operation [9,10,17,18]. Furthermore, the realization of monolithic structure also demands the employment of different actuation strategy to satisfy the stringent requirements in precision microhandling operation since the application of conventional motor to drive the microgripper is insufficient to comply with the specifications.…”

Automatic dextrous microhandling based on a 6-DOF microgripper

“…The size of such grippers is usually in the range of several millimeters to centimeters [14,25,[49][50][51]. Compliant mechanic structures are widely used in microgrippers.…”

“…The jaws or fingers are usually made of metals (e.g. stainless steel [14,22,25], nickel [51]) or silicon materials [50,26]. Some nanogrippers are also developed by applying nanotubes [52] or AFM cantilevers as the end-effector [32].…”