Single Crystal Silicon Actuator Arrays

Massively Parallel Micro Manipulation (1992-1996)

Team Members

Karl F. Böhringer, Bruce Donald, Noel MacDonald, Robert Mihailovich (Cornell)


The design of our actuators is based on microfabricated torsional resonators. They consist of rectangular grids suspended by two rods that act as torsional springs. They are fabricated in a SCREAM process (Single Crystal Silicon Reactive Etching And Metallization). When an AC voltage is applied between the grid and adjacent electrodes, the grid oscillates at resonance frequencies in the high kHz range. The edges of the grid reach deflections of several micrometers out of the substrate plane.

By introducing asymmetries into the resonator grid (such as placing the torsional rods off the center of the grid, or adding poles on one side of the grid) anisotropic lateral forces are generated, thus achieving a motion bias for the object on top of the actuator.

Each actuator can generate motion in one specific direction if it is activated; otherwise it acts as a passive frictional contact. The combination and selective activation of several actuators with different motion bias allows us to generate various motions in the plane. The figure shows such a motion pixel.

Figure 1: Small section of a SCS micro actuator array. Figure 2: Actuator grid with 5 µm tips.
Figure 3: Micro motion pixel with 4 actuators.


Selected Publications

  • K. F. Böhringer, B. R. Donald, N. C. MacDonald, "Programmable Vector Fields for Distributed Manipulation, with Applications to MEMS Actuator Arrays and Vibratory Parts Feeders." International Journal of Robotics Research, 18(2):168-200, February 1999. Paper.
  • Karl F. Böhringer, Bruce R. Donald, Noel C. MacDonald, "Single-Crystal Silicon Actuator Arrays for Micro Manipulation Tasks." IEEE Workshop on Micro Electro Mechanical Systems (MEMS), pp. 7-12, San Diego, California, February 11-15, 1996. Paper.
  • Karl F. Böhringer, Bruce R. Donald, Robert Mihailovich, and Noel C. MacDonald, "A Theory of Manipulation and Control for Microfabricated Actuator Arrays." IEEE Workshop on Micro Electro Mechanical Systems (MEMS), p. 102-107, Oiso, Japan, January 25-28, 1994. Paper.

A complete list of our publications (many of them available online) can be found here.


  • NSF IRI-8802390, IRI-9000532, IRI-9201699, IRI-9530785, and CISE/CDA 98-05548 IRI-9896020, and by a Presidential Young Investigator award to Bruce Donald, NSF/ARPA SGER IRI- 9403903
  • AFOSR, the Mathematical Sciences Institute, Intel Corporation, and AT&T Bell Laboratories
  • ARPA under contract DABT 63-69-C-0019

© Karl F. Böhringer, Department of Electrical Engineering, Box 352500, Seattle, WA 98195-2500, USA