Usually, standard semiconductor processing techniques are used to build integrated circuits. However, such processing techniques can be used to build more than just electronic devices. In the 1980’s, (some say even earlier) these same semiconductor processing techniques were starting to be used to build mechanical devices as well. One such example was the tiny, submillimeter-sized vibrating cantilevers. Such devices could be used for a number of applications including chemical sensors and resonators. To describe the technique of using semiconductor processing techniques to build electro-mechanical devices, the term MEMS (acronym for Micro-electromechanical systems) was coined.
Since then, MEMS techniques have been used in a multitude of fields to build a number of things. Commercial examples include pressure sensors, accelerometers, gyros, fiber optic switching systems, arrayed micro-mirror projectors, DNA sequencing, just to name a few. MEMS are principally based on the electronics industry, and because of it, is ideally suited for mass batch production, making it a cost-effective fabrication technique for large numbers of devices. Additionally, with the fine fabrication accuracy of a micron or smaller, high performance sensors can be constructed.
At the moment, MEMS research and development usually takes a number of years to complete, thus developing new products in the MEMS world can be a costly endeavor. Much of the products available today are grounded on a decade or longer of research, first starting in the university and working its way out to industry. However, as the techniques for creating MEMS devices become more understood, a basis of know-how is being created in both the academic and commercial areas. For some devices, what used to take a number of years to develop, can now be done in just one or two years time.
Some say the sky is the limit for MEMS. As minimum device sizes shrink, with line and space shrinking to below a micron, quantum and structural affects start to dominate over the macroscopic intrinsic material properties that used to be taken for granted on the larger scale. At this point, you could say, this is where the meeting of the nanoscale (or the more commonly used term “nanotechnology”) meets to include a whole new set of unforeseeable new devices and technological advances.
In the lab, there are numerous projects going one exploiting MEMS techniques. It can’t quite be explained in one paragraph, but to name a few, here is a list:
- Sensors built into the fabric of an airplane wing so that they can sense and react to air flow by changing the wing surface resistance; effectively creating a myriad of tiny wing flaps
- Optical switching devices which can switch light signals over different paths at 20-nanosecond switching speeds
- Building supports with embedded sensors that can alter the flexibility properties of a material based on atmospheric stress sensing
- Miniature atomic clock with accuracy of 1 part in 10 billion
- Miniature gas engine batteries
- Blood diagnosis kits with instantaneous results