These weren't terribly useful, but they helped develop the techniques now creating devices with tremendous practical appeal. We're now moving very quickly from research table tops to industrial applications. But tools are a lot harder to make than toys. MEMS researchers must now solve problems that were once just futuristic theoretical barriers. Heat builds up quickly in supersmall devices, significantly affecting their performance.
Fluids take on vexing new properties at the microscopic level.
Even the slightest of impurities can destroy a MEMS device. Here, the smallest airborne dust particles are menacing asteroids bent on random demolition. Ultimately, in their drive to miniaturize, scientists face the insurmountable wall of quantum effects, the inherent fuzziness of individual atoms. Theoretically, they should be able to arrange them one by one like Lego blocks. This remains beyond current technical capability.