It may seem a paradox, but in the future tiny computers may dump electronics and return to their mechanical roots. At the macroscale, mechanical computers are fussy and slow, but when your area is down to a few molecules, electronics have trouble working but mechanical systems do just fine. In addition, these devices don’t use electricity directly, don’t generate electronic signatures, and may be less sensitive to things like radiation that damage electronics. A recent paper in Nature Communications discusses how to 3D print common logic gates using both macro-scale 3D printing techniques and a much smaller version with microstereolithography. You can see a video of gates in action below.
The gates use a bistable flexible mechanism. The larger gates use ABS plastic and measure about 250mm square. The smaller gate measures less than 25 mm square. They also use a special technique to make gates as small as 100 microns theoretically possible, although some of that is future work for the team.
These aren’t the first proposed micromechanical gates. However, many other mechanical designs include a rotational joint to accomplish inversion and this design doesn’t require that. This means it is easier to make and doesn’t suffer from friction and wear problems that other proposals have.
Armed with a functional inverter, the next step was an OR gate. By combining NOT and OR gates, you can easily make a NAND gate, an AND gate, a NOR gate, and any other logic you can dream up.