Design, analysis and fabrication of silicon microfixture with electrothermal microclamp cell Mohsen Hamedi ⇑ , Milad Vismeh, Parisa Salimi School of Mechanical Engineering, University of Tehran, Tehran, Iran article info Article history: Available online 11 April 2013 Keywords: Microassembly Micro-handling devices Microfixture Microclamp Electro-thermal abstract Micro handling devices that are extensively utilized for microfixturing operations are of great interest to the researches for investigating their mechanism and actuation principles. Number of microparts that can be handled simultaneously is an important parameters determining efficiency of the microfixture device. However this issue is not sufficiently addressed in the published literature. This paper discusses a micro- fixturing system equipped with electrothermally actuated microclamps (ETMC) which is used for posi- tioning microparts. The design comprises microclamps on a rotary table, vibrated with random motion through piezoelectric actuation. Each microclamp is composed of two u-shape microactuators which are configured symmetrically to clamp microparts from their sides. Functionality of the microgrippers for submillimeter parts is analytically modeled and simulated using finite element analysis method. The system is then fabricated and experiments are performed to measure variation of microclamp dis- placement with input voltage change. Comparing analytical and numerical results with the measured values validates the analytical model and simulation results. The microfixture is assembled and its prac- ticality for positioning and clamping microparts is realized. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Electrothermal microclamps (ETMC) are devices which can be used for locating, holding and moving micro components. They generate large driving force and sufficient driving distance for a variety of applications. ETMCs are easy to control and are consid- ered for operating in high temperatures. The ETMC structure con- sists of two electrothermal compliant u-shape mechanisms as its clamping arms. The schematic of the ETMC clamping arm is shown in Fig. 1 with its dimensions depicted in Table 1. Driving force to the ETMCs is supplied through resistive joule heating. When voltage difference is applied to the anchors, current flows through the arms. Due to the arms’ width difference and therefore electrical resistance, the temperature in the thin arm, compared to the wide arm, increases more and leads to non-uni- form heating in the structure. Higher elongation of the thin arm is the consequence of this non-uniformity and the cause of in- plane bending mode of the ETMC clamping arm. Studying different types of microassembly methods have been the focus of researchers in recent years. Various microassembly techniques such as capillary driven and fluidic self assembly [1,2] or chip to wafer [3] and wafer to wafer transfer [4] are investigated. Some other studies have focused on the techniques for handling microparts via utilizing microactuators [5]. Along these researches, the actuation methods for the microgrippers and microactuators are highly investigated as well. Piezoelectric [6–9], electrostatic [10,11] electrothermal [12–14] and SMA [15,16] actuation mecha- nisms are the most common microstructure driving principles. In the published literature, handling of submillimeter parts or related actuation mechanisms are extensively investigated how- ever positioning or clamping of microparts are not sufficiently ad- dressed. Moreover, simultaneous accurate locating of microparts is a subject that has not been covered yet. These two factors provide sufficient motivation for this study. The work aims to investigate a microfixture capable of simultaneous micro positioning of four microparts along with electrothermal microclamps which can hold the parts in place. In this article, first the concept of microfixturing cell is intro- duced and then design and analysis of its microclamps is investi- gated using finite element analysis and analytical method. Fabricating the microfixture is followed by experimental measure- ments and the results are compared with FEM and analytical outputs. At the end, the setup for microfixturing cell and microclamping device is illustrated so that the whole system’s functionality can be realized. 2. Design and analysis 2.1. Microfixturing cell design The focus of this paper is to design and manufacture a microfix- turing cell with four clamping stations which is capable of locating 0167-9317/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.mee.2013.03.098 ⇑ Corresponding author. E-mail address: mhamedi@ut.ac.ir (M. Hamedi). Microelectronic Engineering 111 (2013) 160–165 Contents lists available at SciVerse ScienceDirect Microelectronic Engineering journal homepage: www.elsevier.com/locate/mee