Snap Fasteners for Micro Assembly
Single Crystal Silicon Latching Mechanisms (1992-1995)
Karl F. Böhringer, Bruce R. Donald, Noel MacDonald, Rama Prasad
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.
We have conducted a detailed theoretical analysis of design and function
of micro snap fasteners, and describe the fabrication in single crystal
silicon (SCS) technology. To verify the theoretically obtained design
rules we conducted experiments with independent comb drive actuators which
generate micro-Newton forces to actuate and engage the fasteners.
|Figure 1: Engaged micro snap fastener:
single latch design.
||Figure 2: Micro snap fastener: double
||Figure 3: Comb drive actuator
with micro snap fastener.
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. 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.
- Rama Prasad, Karl F. Böhringer, Noel C. MacDonald, "Design, Fabrication,
and Characterization of SCS Latching Snap Fasteners for Micro Assembly."
ASME International Mechanical Engineering Congress and Exposition (IMECE),
no. DSC-16A-1, San Francisco, California, November 12-17, 1995. Paper.
A complete list of our publications
(many of them available online) can be found here.
- ARPA under contract DABT 63-69-C-0019
- NSF grant ECS-8619049
- NSF IRI-8802390, IRI-9000532, IRI-9201699, and by a Presidential Young
Investigator award to Bruce Donald, NSF/ARPA SGER IRI-9403903
- Air Force Office of Sponsored Research, the Mathematical Sciences
Institute, Intel Corporation, and AT&T Bell laboratories.
© Karl F. Böhringer, Department of Electrical Engineering, Box
352500, Seattle, WA 98195-2500, USA