Research Article Modeling of a High Force Density Fishbone Shaped Electrostatic Comb Drive Microactuator Megat Muhammad Ikhsan Megat Hasnan, 1 Mohd Faizul Mohd Sabri, 2 Suhana Mohd Said, 1 and Nik Nazri Nik Ghazali 2 1 Department of Electrical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia 2 Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia Correspondence should be addressed to Mohd Faizul Mohd Sabri; faizul@um.edu.my Received 5 March 2014; Revised 22 June 2014; Accepted 23 June 2014; Published 21 July 2014 Academic Editor: Jingyan Dong Copyright © 2014 Megat Muhammad Ikhsan Megat Hasnan et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Tis paper presents the design and evaluation of a high force density fshbone shaped electrostatic comb drive actuator. Tis comb drive actuator has a branched structure similar to a fshbone, which is intended to increase the capacitance of the electrodes and hence increase the electrostatic actuation force. Two-dimensional fnite element analysis was used to simulate the motion of the fshbone shaped electrostatic comb drive actuator and compared against the performance of a straight sided electrostatic comb drive actuator. Performances of both designs are evaluated by comparison of displacement and electrostatic force. For both cases, the active area and the minimum gap distance between the two electrodes were constant. An active area of 800 × 300 m, which contained 16 fngers of fshbone shaped actuators and 40 fngers of straight sided actuators, respectively, was used. Trough simulation, improvement of drive force of the fshbone shaped electrostatic comb driver is approximately 485% higher than conventional electrostatic comb driver. Tese results indicate that the fshbone actuator design provides good potential for applications as high force density electrostatic microactuator in MEMS systems. 1. Introduction Actuators are used to convert nonmechanical input energy into mechanical output energy. Actuators can be used in dif- ferent scales, ranging from macroscopic actuation through electromagnetic motors, hydraulics and pneumatics, to mic- roscopic actuation where the actuators are of the order of microns for MEMS applications. In MEMS applications, actuators are used to achieve positioning [1], such as posi- tioning a cantilever tip to perform as microgrippers to move miniature objects [2], or to access a specifc data point in data storage systems such as in the “Millipede project” [3]. Te main parameters that need to be considered for microactu- ator performance include displacement, response time, load capacity, actuation force, resolution, degrees of freedom, and size [4–7]. Te most common actuators are piezoelectric actuators, electromagnetic actuators, electrostatic actuators, thermal actuators, and electrochemical actuators, each with their respective advantages and drawbacks [8–12]. For exam- ple, electromagnetic actuators possess a high efciency in converting electrical energy into mechanical work but are bulky and require a high operating voltage [13]. On the other hand, piezoelectric actuators provide a high actuation force and speed but have low intrinsic displacement [14, 15]. Electrostatic actuators have some favourable performance characteristics, such as a large displacement, as demonstrated by Grade et al. [16] and Liu and Kenny [17]. However, a main drawback of the electrostatic microactuator is its large active area, as a typical electrostatic actuator confguration comprises a large array of interdigitated electrodes which occupy a large surface area. Te mechanism of operation for electrostatic actuators can be described as follows. A set of interdigitated electrodes (or combs) of opposite polarities are arranged in order to set up an electric feld. One set of the combs is fxed, whilst the other set is Hindawi Publishing Corporation e Scientific World Journal Volume 2014, Article ID 912683, 8 pages http://dx.doi.org/10.1155/2014/912683