New optofluidic technology improves sensor performance

Oregon State University researchers have managed to combine the diatom with a specialized inkjet printing method and optical sensing to develop a super sensitive device. How sensitive? About 10 million times as the current sensor technology.
Nanoscale journal first published the findings and an “optofluidic” technology patent based on the design has been approved.
The primary use of this technology when used with other devices is the improvement of the sensing of cancer biomarkers. Other important uses could be in forensics or during military combat operations. The technology can possibly detect illegal drugs or determine the presence of pesticide in food.
The wide range of use (from health monitoring to biological experiments) is due to the very high sensitivity amidst lower cost of the technology.
Professor Alan Wang, corresponding author of the study, believes that most existing sensors are really not good enough despite them being able to “detect compounds at levels of one part per billion.” Wang is an OSU assistant professor of electrical engineering.
“With this approach, we can detect some types of compounds at less than one part per trillion, about the level of a single molecule in a small sample,” adds Wang. He said that doing such is quite difficult and says that their technology can now work with ultra-small samples at high speeds with lower costs.
Compounds are identified by the system through a combination of advanced optics and fluidic environment. In most systems with the same type, fluids tend to flow over a surface which effectively limits the transport of certain molecules that needs to be identified.
With diatoms, which act as natural photonic crystals, uses convection forces against diffusion in order to accelerate and concentrate molecules in a space where usually photons from optical sensors get trapped. These photons then interact and identify the chemical compound via optical signatures.
What is a diatom exactly? Wang explains that is a natural and living type of phytoplankton that has the ability to create very minute and precise structures. “When liquids are deposited on it with carefully controlled inkjet devices, the droplets evaporate quickly, but, in the process, carry the molecules of interest to the diatom surface. This is the key to increasing the sensitivity of the photonic measurements.”
Compounds can then be identified and quantified quickly and accurately by this new sensor technology.
The researchers tried to identified trinitrotoluene (TNT) in one of the demonstrations of the technology. TNT is more commonly known as one of the chemicals that make up explosives. In military operations, TNTs are often packaged inside mines which are often hidden from plain sight. Current technologies have a hard time sensing TNT because of its limited evaporation, i.e., few molecules escape from its container that allows detection.
The result of the demonstration is astounding: the technology was able to identify TNT with a million times more sensitivity. Wang envisions that a special fast and accurate bomb monitor could be built from their research which will save a lot of lives in battle grounds. Other commercial applications of this technology are already being studied.
This research was given support by the U.S. Department of Defense and the National Institutes of health with collaboration from the Washington State University.

More information can be found at: Oregon State University.

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