Discuss as:

Tiny sensors that measure amplitude are big step

Vijay Kumar / Purdue University

Researchers have learned how to improve the performance of sensors that use tiny vibrating "microcantilevers," like the one pictured here, to detect chemical and biological agents for applications from national security to food processing.

Anyone who watched the recent X-Games coverage heard commentators obsess about "amplitude" — how high snowboarders such as Shaun White soar above the lip of the superpipe to perform aerial tricks.

Scientists more concerned with using vibrating sensors to detect harmful chemicals in the air we breathe and food we eat than White's frontside double cork 1260 share the love for amplitude.

In their case, they've found that a change in the amplitude of a tiny sensor's vibration is a reliable indication that a chemical of interest has glommed onto it. 

Sensors that measure shifts in frequency — how often a vibrating motion repeats itself — when a chemical of interest sticks to it have been around for a while, noted Jeffrey Rhoads, a mechanical engineer at Purdue University in West Lafayette, Indiana.

"But when the devices get smaller, that can be harder to do due to noise," he explained to me Tuesday. That is, at small scales, scientists have a hard time detecting changes in frequency that are due to the chemical of interest from changes because of other factors.

To get around this, Rhoads and colleagues found that they can measure changes in amplitude instead. The breakthrough, he said, could lead to applications everywhere from food safety and national security to, eventually, biomedical research.

Proof-of-concept experiments showed that change in amplitude was a more reliable way to detect the presence of small quantities of methanol gas than the frequency approach.

Applied to other gases this could be useful, for example, when attempting to determine the safety of food, Rhoads said. "If there's a little bit of something bad, the whole thing is shot."

Looking to the future, the team hopes to apply these sensors to things like detecting the concentration of certain cells in a person's blood, for example.

To get there will require improvements to measure not just the presence of a chemical, but also its concentration. Doing so will require better understanding of the chemistry of the chemicals of interest.

Findings are detailed a paper appearing online this week in the Journal of Microelectromechancial Systems.

More on sensor technology:


John Roach is a contributing writer for msnbc.com. To learn more about him, check out his website. For more of our Future of Technology series, watch the featured video below.

The modernist kitchens of Grant Achatz are known for using experimental equipment to produce unusual cuisine, thanks to an unusual partnership with PolyScience, a lab equipment.