Micro Snap Fasteners

Joint work with Rama Prasad, Noel MacDonald, and Bruce Donald.
Micro Snap Fastener (Spring '95)

A snap fastener is a deformable device consisting of a pair of mating surfaces that ``snap'' together during assembly. Because of the simple, linear assembly motion, snap fasteners have a wide range of applications in micro assembly tasks, e.g. for devices with multiple or layered components, or micro opto-mechanical plugs. At the micro scale, conventional types of fasteners like screws and hinges are unlikely to work due to present fabrication constraints and large friction forces. Micro snap fasteners also have great potential to be used in sensors with memory.

Engaged Micro Snap Fastener (Spring '92)

We have conducted a detailed theoretical analysis of design and function of micro snap fasteners [1], and describe the fabrication in single crystal silicon (SCS) technology [4]. To verify the theoretically obtained design rules we conducted experiments with independent comb drive actuators [2] which generate micro-Newton forces to actuate and engage the fasteners.

Comb Drive Actuator (Summer '94)

There exist efficient computational tools for analysis and simulation of snap fasteners which make it possible to automatically generate the appropriate design of a snap fastener given just the functional specification of the device [3]. Combined with the highly automated VLSI fabrication process, this allows a virtually completely automated production, making snap fasteners one of the very few devices that can be fabricated automatically given only their functional specification.


  1. Rama Prasad, K.-F. Böhringer, and N. C. MacDonald, Design, Fabrication, and Characterization of SCS Latching Snap Fasteners for Micro Assembly, To appear in Proc. ASME International Mechanical Engineering Congress and Exposition (IMECE'95), San Francisco, California (November 1995).

    Also of interest:

  2. R. Prasad, N. C. MacDonald, and D. Taylor, Micro-Instrumentation for Tribological Measurements. Transducers'95, Stockholm, Sweden (June, 1995).
  3. K.-F. Böhringer, A Computational Approach to the Design of Micromechanical Hinged Structures. Proceedings of the ACM SIGGRAPH Symposium on Solid Modeling and Applications, Montréal, Québec, Canada (May, 1993).
  4. Z. L. Zhang and N. C. MacDonald, An RIE Process for Submicron, Silicon Electromechanical Structures, Journal of Micromechanics and Microengineering 2(1):31-38 (March 1992).