Since its invention in the 1950s, the turbo molecular pump has become the workhorse of modern vacuum technology. But its large size and weight, combined with heavy power consumption, render it unsuitable for portable applications. That means no matter how small the analytical instrument, such as a mass spectrometer or gas sensor, it must be tethered to a device the size of a shoebox to do its job.
But what if a micro vacuum pump could be developed? That was the question DARPA asked of scientists in 2009 in an effort to solve the problem of placing a sensor and vacuum pump that were small and light enough to be mounted on an unmanned aerial vehicle (UAV).
A Honeywell lab team took up this challenge with a new approach. We borrowed a page from conventional turbine compressors and applied the latest silicon micro fabrication techniques. We machined hundreds of thousands of micron-sized turbine blades onto the surface of a silicon wafer the diameter of a penny. When the wafer is rotated at high speed, the result is an ultra-high vacuum in a small chamber, all on less than a watt of energy.
While the pump could solve DARPA’s goal with respect to UAVs, it also could lead to breakthrough applications in other areas. GPS, for instance, is an excellent way to determine location on a mobile device. But a tiny atomic clock embedded on a smartphone -- one enabled by an even smaller and flatter micro vacuum pump -- could vastly improve personal location technology. Sensors powered by this pump could enhance the power of small medical diagnostic instruments, in essence giving them a nose. Longer-term smart-device applications could include sensors that measure air quality or personal health statistics.
Near term, the micro vacuum pump could lead to the development of a universal gas detector for commercial-industrial applications. Currently, most gas detectors are gas specific, so you need a specific detector for each gas you’re measuring. With a micro vacuum pump, one device based on mass spectrometry could be programmed with software to measure 20 different gases simultaneously, and the entire apparatus could be part of a portable field device or mounted on a wall. We continue to work with our partners to determine potential applications for this miniature pump, which over time could turn out to be a whole new kind of workhorse.
Wei Yang, Ph.D, joined Honeywell in 1995 and is currently a principal research scientist at the company’s Sensors and Wireless Laboratories in Plymouth, Minn.
Thanks Rob. There is more research to do on further miniaturizing the vacuum pump as well as packaging and ruggedization for specific applications, but we're already at a stage where it could be paired with a gas sensor and mounted on a UAV to be used with bio-terror or bio-hazard detection. Industrial and consumer applications will take longer because the vacuum pump must be much smaller. However, I am confident we'll see some of these applications in the next few years. We continue to explore development possibilities within Honeywell, but would also welcome interest from other companies that may have a particular application idea.
It sounds like this research is just the seed of a potentially promising tree of ideas. Micro-turbine technology for vacuum pumps are one application. I suppose small pumps for extremely hazardous fluids is another. Fluids do funny things at small length scales. Growing small silicon turbine blads is a neat area of research. Keep us informed on this!
These things really suck, Rob. Sorry, it's late and I could not resist. In fact, this is VERY fascinating and begs all sorts of questions. Like, how fast do these micropumps spin? What sort of bearings support the impellers? Would such a micropump in a mobile phone be audible?
Nice article, Wei. Seems like there would be a wide range of applications for a micro vacuum pump. You mentioned a number of possible applications. Do you know if these additional applications are in the works?
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