Heard about the coming age of nanobots, have you? You’ll believe it when you see it, right? Me too. However, looks the building blocks for those micromachines are up and running. Ever thought you’d see a chip-scale motor? A gear train smaller than a pinhead?
This alignment clip is used in conjunction with a transmission. This complex device is entirely batch-fabricated, with no assembly required. Amazing!
(Sandia National Laboratories)
Here’s a birds-eye overview of a chip-scale, six gear train in operation. The black, pointed objects are tiny probes applying power to the “circuit” that runs the train. The tiny semi-circle in the center is the actual gear train. The object on the right is the actuator mechanism, where electrical forces are converted to mechanical movement, which then applies the mechanical power to the gears. This is a silicon machine.
And here’s a closeup of that tiny gear train running.
Here’s a comb drive linear actuator. The basic princle is that of opposite charges attracting and like charges repelling. The actuator in the center, attached to the bottom comb, is negatively charged. When the top comb is positively charged, the bottom comb is attracted, moving towards it. When the charge is reversed, the bottom comb is pushed away. Simple, no? You can see the charge reversing by the top comb alternately lighting up and going dark.
Perhaps what’s most impressive about these machines is their manufacturability. They are made from the same materials (silicon wafers and aluminum) and the same photo-lithography techniques as the chips in your computer. Most people don’t realize (why would they?) that those microchips are not single layer devices, but complex, 3-D, multilayer stacks of silicon, conductors, and dielectrics. Imagine building complex, reliable, low power, low cost machines using the same technologies. Impressive.
There are at least three facilities pursuing MEMS (micro electromechanical machine systems) that I’m aware of: Sandia National Lab, The Applied Physics Lab and UC Berkely. Darpa is a primary funding agency.