A pair of
tweezers
shown
is formed by
formed by
two mirrored structures connected alongside each other. The
tweezers open when current is applied to the pads, indicated
by the red arrows.
The movement is induced by hot arm pairs
similar to that described for cantilever electrothermal
actuators.
After fabrication,
the
beam tweezers were largely affected by stiction.
With an applied voltage of
20V the separation of the arms increases
to
9.6µm.
Although the video clip
above confirms that the tweezers structure works, the actuators’
major downfall is the length of its hot beams. When the length
of a beam increases the effects of stiction, heat loss and
residual stress become more significant. A long beam has much
more surface area than a short beam and it will be less
efficient at reaching high temperatures. Also, beam deflection
caused by non uniform stress is proportional to beam length.
The deflection can be upward or downward depending on the
stress gradient in the beam and it greatly reducing the
efficient of the actuator.
