Chemical detection A portable, shoe-box-sized chemical detector

Published 18 December 2017

A chemical sensor prototype will be able to detect “single-fingerprint quantities” of substances from a distance of more than 100 feet away, and its developers are working to shrink it to the size of a shoebox. It could potentially be used to identify traces of drugs and explosives, as well as speeding the analysis of certain medical samples. A portable infrared chemical sensor could be mounted on a drone or carried by users such as doctors, police, border officials and soldiers.

A chemical sensor prototype developed at the University of Michigan will be able to detect “single-fingerprint quantities” of substances from a distance of more than 100 feet away, and its developers are working to shrink it to the size of a shoebox.

It could potentially be used to identify traces of drugs and explosives, as well as speeding the analysis of certain medical samples. A portable infrared chemical sensor could be mounted on a drone or carried by users such as doctors, police, border officials and soldiers.

U-M notes that the sensor is made possible by a new optical-fiber-based laser that combines high power with a beam that covers a broad band of infrared frequencies—from 1.6 to 12 microns, which covers the so-called mid-wave and long-wave infrared.

“Most chemicals have fingerprint signatures between about 2 and 11 microns,” said U-M researcher Mohammed Islam, who developed the laser. “Hence, this wavelength range is called the ‘spectral fingerprint region.’ So our device enables identification of solid, liquid and gas targets based on their chemical signature.”

The project is a collaboration among U-M, global technology company Leidos, fiber makers IRflex and CorActive and U-M startup Omni Sciences, which was founded by Islam. The project is funded by the U.S. Intelligence Advanced Research Projects Activity.

Islam, U-M professor of electrical and computer engineering and biomedical engineering, and his team built their device with off-the-shelf fiber optics and telecommunications components, save one custom-made optical fiber. This approach ensures that the laser will be reliable and practical to manufacture at a reasonable cost.

“We’ve shown we can make a $10,000 laser that can do everything a $60,000 laser can do,” Islam said.

Broadband infrared lasers are typically built up from a laser that produces very short pulses of light, and then a series of amplifiers ramps up the power, but this approach is limited to laboratories. In addition to their high costs, these components can’t yet shrink small enough to fit into a handheld device. Plus, the use of lenses and mirrors would make the device sensitive to jostling and changes in temperature.