Researchers worldwide are currently working on creating very small nanosized robots with a host of capabilities embedded, including complex electronic circuits, sensors, antennas, and photovoltaics. One of the most complicated techniques that scientists have to perform with such small robots is designing them to move by bending. The Cornell team has been able to create micron-sized shape memory actuators that enable atomically thin two-dimensional materials to fold themselves into 3D configurations.
The folding process requires a short jolt of voltage, and once the material bends, it holds its shape even if the voltage is removed. The Cornell team created a demonstration that folds a flat material into what the team calls the world’s smallest self-folding origami bird. Cornell professor of physics Itai Cohen says the goal is to have microscopic robots that have brains on board.
The researcher wants to create robots with appendages driven by complementary-metal-oxide-semiconductor transistors, which is essentially a computer chip on a robot that’s 100 microns on a side. Cohen envisions a future where a million fabricated microscopic robots could be released from a wafer and fold into shape and perform specific tasks, including the ability to assemble into more complicated structures.
Cohen says the most challenging part is making materials that respond to CMOS circuits. That most complicated task is what the researchers at Cornell have done with the shape-memory actuator driven by voltage. The actuators can bend with a radius of curvature smaller than a micron which is the highest curvature of any voltage-driven actuator by order of magnitude.
The smallest curvature is critically important because in microscopic robot manufacturing, the robot’s size determines how small the various appendages are controlled; the tighter the bends and the smaller the folds, the smaller the overall footprint of the robot. The bots are made of nanometer-thin layers of platinum with titanium or titanium dioxide film on top. They also feature rigid panels of silica dioxide glass sitting on top of those layers. When a negative voltage is applied, the robot unfolds to a pristine state.