Article

Simulation of shaped comb drive as a stepped actuator for microtweezers application

Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg, Man., Canada R3T 5V6
Sensors and Actuators A: Physical 01/2005; DOI: 10.1016/j.sna.2005.03.031

ABSTRACT Finite element analysis is used to simulate electrostatic actuated, shaped comb drives operating under dc conditions (zero actuating frequency). A dynamic multiphysics model is developed using the arbitrary Lagrangian–Eulerian (ALE) formulation. Results show the coupled interaction between the electrostatic and mechanical domains of the transducer. The analysis is based on the evolution of electrostatic force versus comb finger engagement. The relationship between incremental lateral displacement and actuation voltage illustrates the potential for stepped movement for a shaped comb drive. Additionally, through numerical simulations, this project determines an optimum design for a dc-actuated comb drive, which has controllable force output and stable engaging movement.

0 Bookmarks
 · 
126 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a method for fabricating a fundamental MEMS tool—microtweezers. Microtweezers offer an attractive option to meet the increasing need to grasp, manipulate and excise microstructures or biological components. The microtweezers presented here augment a standard micromanipulator, allowing precise positioning in three dimensions. An additional micro-drive control knob, which is affixed to the micromanipulator, allows actuation of the tweezer tips through the use of a tether-cable drive system. This drive actuates the tweezer tips by the reciprocating motion of two microfabricated parts: the tweezers and tweezer box. A simple three-layer planar fabrication scheme allows for a broad range of tweezer styles (straight and serrated tips) and sizes (microns to millimeters). For these studies, 20 µm wide and 10 µm thick nickel beams were developed for the tweezer tips, which could endure 20 mN of force. To demonstrate the concept of microassembly, pick and place operations were performed on 10 µm thick film structures. Additional functionality was achieved by integrating platinum-black microelectrodes into parylene-coated tweezers to allow electrophysiological functions such as cellular stimulation and recording. Ultimately, this unique and simple design affords extraordinarily delicate control that is potentially beneficial for applications in microassembly, electrophysiology and microsurgery.
    Journal of Micromechanics and Microengineering 04/2008; 18(6):065004. · 1.79 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: An analytical method was developed for maintaining a constant levitation height during dynamic operation of reciprocating comb-drive actuators. The dependence of the translational position and the levitation height on the applied voltage was used to design waveforms that maintain a given translational motion without altering the levitation height. An experimental protocol was established for determining the necessary geometric factors of a particular comb-drive design, which were then used to generate constant-velocity levitation waveforms. The analytical model was tested experimentally by examining the levitation and translation positions of a surface micromachine under both compensated and uncompensated signals. A significant reduction in the range of levitation was obtained over the entire amplitude of the oscillatory motion, while the translational motion remained relatively unchanged. Design and fabrication effects on the compensated levitation height of an oscillating surface micromachine are discussed in the context of analytical and experimental results.
    Sensors and Actuators A Physical 01/2008; 143(2):383-389. · 1.84 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a new topology optimization scheme for nonlinear electrostatic systems actuated by Coulomb’s forces. For successful optimization, computational issues such as (i) alternating governing equations with respect to spatially defined design variables, (ii) imposing interaction boundary conditions between insulator (air) and conductor (solid) and (iii) control of minimum geometrical feature sizes must be addressed. To address the first two issues, the paper presents a monolithic formulation based on continuum mechanics theory which simultaneously calculates the electric potential and structural displacements. To interpolate between insulator and conductor with continuous design variables, the monolithic approach distinguishes between the permittivity value of the electric Poisson’s equation and that of Maxwell’s stress tensor. For the optimization, standard material interpolations are used for Young’s modulus and permittivity values. Moreover, a recently developed morphology filter is applied to control electrode gaps and other geometrical features.
    Computer Methods in Applied Mechanics and Engineering 01/2008; · 2.62 Impact Factor

Full-text (2 Sources)

View
26 Downloads
Available from
Jun 1, 2014