Hordes of invisible robots are on the march! Word is that they are trying to invade our bodies! Run, take cover! They are everywhere… nowhere to hide!
In what may at first blush sound like a mashup between The War of the Worlds and Innerspace, a research group at Cornell University has developed a very clever new actuator technology at a scale previously unheard of. Miskin et al. have successfully fabricated robots less than one tenth of a millimeter in size (rendering them invisible to the naked eye), and able to walk under the power of four tiny legs.
These legs, 7 nanometer thick layers of platinum, are the actuators. Lithographically patterned, the actuators are designed to bend via electrochemical interactions. Each leg is powered by an individual solar cell on the robot’s back. When a laser is focused on a particular solar cell, the attached leg moves. By coordinating the pattern of laser pulses actuating each leg, the researchers are able to generate a walking motion that can propel the robot under controlled movement. The actuators operate at very low voltages (200 microvolts) and low power (10 nanowatts).
The robots are fabricated from silicon wafers using standard doping, lithography and metallization processes to create the robot’s circuitry (silicon photovoltaics and associated wiring). As a next step, the legs are patterned and deposited. Over one million robots can be produced per four inch wafer.
At present, the robots can only walk — they cannot sense their environment or interact with it. Also, requiring an external laser to precisely focus on the solar cell for each leg limits the use of the robot for many applications. However, as the robots are compatible with standard CMOS processing, the authors anticipate rapid evolution of the technology, with sensory inputs, onboard processing, and alternate sources of energy soon to be added. They expect such robots to ultimately cost considerably less than one cent each.
With these improvements, it is hoped that these robots will one day be able to be injected into the human body to maintain health and treat disease. With a degree of added autonomy, the robots may also be able to work together in swarms in the future to accomplish larger goals.