Microtechnology
The two photographs below appeared in The
MEMS Handbook, edited by Mohamed Gad-el-Hak, published by CRC Press
(2002). Directly below is the first walking microrobot with a Swedish
wasp relishing a ride on its back. The out-of-plane rotation of the
eight legs is obtained by thermal shrinkage of polyimide in V-grooves
(PVG). Leg movements are effected by sending heating pulses via integrated
heaters causing the polyimide joints to expand. The size of the silicon
legs is 1000x600x30 microns, and the overall chip size of the robot
is 15x5x0.5 mm. The walking speed is 6 mm/s and the robot can carry
50 times its own weight. Photograph by Per Westergard, Vetenskapsjournalisterna,
Sweden, courtesy of Thorbjorn Ebefors, Royal Institute of Technology,
Sweden.
The second picture is a scanning electron
micrograph of a 12-layer microchain fabricated in nickel using the
Electrochemical Fabrication (EFAB) technology. Overall height of
the chain is around 100 microns and the width of a chain link is
about 290 microns. All horizontal links are free to move, while the
vertical links are attached to the substrate. By simply including
a sacrificial layer beneath the links, the entire chain can be released
from the substrate. The microchain is fabricated in a pre-assembled
state, without the need for actual assembly. The beast towering over
the microchain is a humble, picnic-loving ant.
Photograph courtesy of Adam L. Cohen,
MEMGen Corporation, U.S.A. |
