Lasers Allow Non-Invasive Tests

Tuesday, Jan 24, 2012

What if a person with diabetes could measure blood sugar without a pinprick? What if a quick scan of a person’s breath could reveal how their kidneys are doing or whether they have asthma?

These are the kinds of potential technologies that drew more than 100 business leaders, investors, medical researchers, scientists and engineers to Princeton on Oct. 12 for a meeting that underscored how one fundamental technology can spur multiple benefits for human health.

The meeting explored the medical applications of lasers and sensors tuned to operate with mid-infrared light, a part of the spectrum that is particularly useful for detecting biologically relevant molecules. It was the most recent Investment Focus Group workshop hosted by Mid-Infrared Technologies for Health and Environment (MIRTHE), a multi-institutional research center funded by the National Science Foundation and based at Princeton.

Dual pictures of a hand in visible and in infra-red light
Two images of the same hand, one in visible light, the second in infra-red. The white dot on the forefinger of the lower image shows the infrared beam hitting the skin. The power of the laser is on par with the heat generated at the palm of the hand, which also appears white in the infrared image.  (Images courtesy of Sabbir Liakat)

Behind the technologies is a device known as a quantum cascade laser, which offers a compact, inexpensive and easy-to-use method for producing and detecting mid-infrared light. Among the uses currently being developed is a device that scans a persons’ skin to reveal his or her blood glucose level — a project that is now supported by Princeton’s Eric and Wendy Schmidt Transformative Technology Fund. Compared to the current method of drawing and testing a drop of blood, the innovation could provide much more control over diabetes.

Another area of research involves sensing nitric oxide or ammonia in a person’s breath. Technology under development at Princeton could allow much more finely tuned detection of nitric oxide than was previously possible, allowing a more fundamental understanding of the role of the gas in the body and in disorders such as asthma. A similar scan for ammonia could give doctors critical information about the kidneys. More precise and frequent monitoring of these conditions might allow reduced use of steroids or dialysis, saving medical costs and avoiding potential complications.

Dr. Raed Dweik, a professor of medicine at the Cleveland Clinic, and a collaborator with MIRTHE, said mid-infrared sensing has the potential to overcome the drawbacks of existing technologies, which are either too bulky, require too much expertise or provide too little information to be useful in day-to-day medicine. “I think it has great potential for moving breath sensing forward,” he said.

The increasing understanding of quantum cascade lasers also is leading to their possible use in laser surgery, because they could provide more controlled, less damaging incisions than conventional lasers. Princeton engineers are helping develop surgical lasers that are currently being tested in experimental corneal surgeries at Johns Hopkins University.

Claire Gmachl, the Eugene Higgins Professor of Electrical Engineering and director of the MIRTHE research center, said the technology and science have matured dramatically since the center was created in 2006.

“The energy was quite amazing,” Gmachl said of the investment workshop. “To see the technology grow and spread and be taken up by other people is very gratifying.”

Read more articles from the Winter 2012 EQuad News, a publication of Princeton University's School of Engineering and Applied Sciences