Design and Validation of a Single-SOI-Wafer 4-DOF Crawling Microgripper

Abstract

This paper deals with the manipulation of micro-objects operated by a new concept multi-hinge multi-DoF (degree of freedom) microsystem. The system is composed of a planar 3-DoF microstage and of a set of one-DoF microgrippers, and it is arranged is such a way as to allow any microgripper to crawl over the stage. As a result, the optimal configuration to grasp the micro-object can be reached. Classical algorithms of kinematic analysis have been used to study the rigid-body model of the mobile platform. Then, the rigid-body replacement method has been implemented to design the corresponding compliant mechanism, whose geometry can be transferred onto the etch mask. Deep-reactive ion etching (DRIE) is suggested to fabricate the whole system. The main contributions of this investigation consist of (i) the achievement of a relative motion between the supporting platform and the microgrippers, and of (ii) the design of a process flow for the simultaneous fabrication of the stage and the microgrippers, starting from a single silicon-on-insulator (SOI) wafer. Functionality is validated via theoretical simulation and finite element analysis, whereas fabrication feasibility is granted by preliminary tests performed on some parts of the microsystem.

Comparative evaluation of three image analysis methods for angular displacement measurement in a MEMS microgripper prototype: a preliminary study

“…As previously noted in [10], the major limitation associated with this procedure is due to the inability of the ADMFFT to measure angular displacements less than a tenth of a degree, typical of MEMS devices for biomedical applications such as microgrippers. However, some microgrippers actuated by rotary comb-drive, as those studied in this work, are powered with voltages much higher than 30 V [25], [26] and therefore it was considered relevant to define whether this method could be used for the characterization of other MEMS devices. In order to evaluate the limit of applicability of the ADMFFT, we proceeded in this way: once an image that presented a pattern like the one shown in Figure 5 was identified, it was rotated of a quantity reported in Table 1, where SET1 and SET2 correspond to two set of rotation, the first consisting of rotations less than one degree, the second higher than one degree; in particular, the rotation values of the first set correspond to the measurements obtained from the images acquired during the experimental campaign, using the SAM.…”

Analytical Modeling of a New Compliant Microsystem for Atherectomy Operations

“…The joint replacement step is performed by making use of the CSFH (conjugate surfaces flexure hinge) [ 38 ]. The approach has been used to obtain different multi-DoF, multi-hinge devices, such as 3-DoF platforms [ 39 , 40 ] and microgrippers for biosample characterization [ 41 , 42 , 43 , 44 , 45 ] that have also been considered for use in a surgical scenario [ 46 , 47 , 48 ].…”

Demonstration of Heterogeneous Structure for Fabricating a Comb-Drive Actuator for Cryogenic Applications

“…Among these, electrostatic-based microactuators have been extensively studied as attractive positioning devices because of their large displacement range, easy manufacturing, and high system integration [12][13][14][15]. In particular, comb-drive actuators consisting of two interdigitated finger structures have been widely employed as microgrippers [16,17], optical shutters [18], micromechanical gears [19], and multidimensional microstages [20][21][22][23][24].…”