Engineers at Cornell University have developed new nanotechnology capable of folding the material into an origami bird only microns in size. The goal is to build ultra-small functioning robots with a host of capabilities, which could be outfitted with different hardware, including complicated electronic circuits, photovoltaics, sensors and antennas. Those tiny robots also need to be able to move. To do that, the engineers have created micron-sized shape memory actuators, which enable 2D materials to fold into themselves to produce 3D configurations, such as animals created using origami techniques. All that's needed is a quick jolt of voltage, and once the material is bent, it retains its shape, even though the voltage is turned off.
"We want to have robots that are microscopic but have brains on board," stated Itai Cohen, a physics professor at Cornell. "So that means you need to have appendages that are driven by complementary metal-oxide-semiconductor (CMOS) transistors, basically a computer chip on a robot that's 100 microns on a side." The new actuators can bend with a radius of curvature smaller than a micron, making them the world's smallest curvature of any voltage-driven actuator. That flexibility is essential as the robot's size is determined by how small its appendages can be made to fold. The tighter the bends, the smaller the folds, and the tinier the footprint for each machine. It minimizes power consumption as well, an important aspect when it comes to tiny robots.
The actuators were designed using a nanometer-thin layer of platinum topped with a titanium or titanium dioxide film. Several rigid panels of silicon dioxide glass sit atop those layers, and when a positive voltage is introduced to the actuators, oxygen atoms are driven into the platinum, swapping places with the platinum atoms. The process causes the platinum to expand on one side in the seams between the inert glass panels, which bends the structure into a predesigned shape. When a negative voltage is applied, the oxygen atoms are removed, and the platinum returns to its original shape.
Varying the glass panels' patterns and positioning the platinum on top or the bottom can create any number of origami shapes, allowing for a myriad of different types of locomotive robots. The engineers are currently working to integrate their shape memory actuators with circuits to make walking robots with foldable legs and sheet-like robots that move by undulating forward. The engineers feel this new development could lead to nano-Roomba-type robots that can clean the bacterial infection from human tissue, micro-factories, and robotic surgical instruments significantly smaller than anything in use today.