A new propulsion system devised for microscopic robots could in the future enable these micrometer-sized devices to travel through blood vessels, probe internal organs or provide targeted drug therapy. The microbots are equipped with a simple silicon photovoltaic circuit that powers their legs, which are made of electrochemical actuators.
The tiny actuators designed by researchers from the University of Pennsylvania and Cornell University fold and unfold when minuscule amounts of electric current are applied. The current causes ions from a surrounding Microscopic robots incorporate a simple silicon photovoltaics circuit and four electrochemical actuators that function as legs. When laser light shines on the photovoltaics, the robots walk. Source: Cornell Universitysolution to adsorb to the actuator’s surface, modifying the stress in the leg and thereby causing it to bend. The electrochemical actuators are synthesized with the same nanofabrication techniques as those used to make computer chips. Shining a laser on a photovoltaic circuit induces the actuators to bend and unbend, and as the operator alternates between bending the front and back legs by shining the laser on different regions of the solar cells, the robot is propelled.
The 5 microns-thick devices operate on a voltage of just 200 millivolts and power of 10 nanowatts, and by application of lithography and other standard microchip manufacturing processes as many as a million of the bots can fit onto one 4 in silicon wafer. The researchers plan to incorporate more sophisticated electronics and onboard computational capabilities in the march toward mass-manufactured, silicon-based functional microrobots.