  The ability to control high-voltage actuator arrays relies, to date, on
expensive microelectronic processes or on individual wiring of each actuator to
a single off-chip high-voltage switch. Here we present an alternative approach
that uses on-chip photoconductive switches together with a light projection
system to individually address high-voltage actuators. Each actuator is
connected to one or more switches that are nominally OFF unless turned ON using
direct light illumination. We selected hydrogenated amorphous silicon as our
photoconductive material, and we provide complete characterization of its light
to dark conductance, breakdown field, and spectral response. The resulting
switches are very robust, and we provide full details of their fabrication
processes. We demonstrate that the switches can be integrated in different
architectures to support both AC and DC-driven actuators and provide
engineering guidelines for their functional design. To demonstrate the
versatility of our approach, we demonstrate the use of the photoconductive
switches in two distinctly different applications control of micrometer-sized
gate electrodes for patterning flow fields in a microfluidic chamber, and
control of centimeter-sized electrostatic actuators for creating mechanical
deformations for haptic displays.
