Princeton Engineers Make Breakthrough İn Ultra-sensitive Sensor Technology

Princeton researchers have invented an extremely sensitive sensor that opens up new ways to detect a wide range of substances, from tell-tale signs of cancer to hidden explosives. The sensor, which is the most sensitive of its kind to date, relies on a completely new architecture and fabrication technique developed by the Princeton researchers. The device boosts faint signals generated by the scattering of laser light from a material placed on it, allowing the identification of various substances based on the color of light they reflect. The sample could be as small as a single molecule.

The technology is a major advance in a decades-long search to identify materials using Raman scattering, a phenomena discovered in the 1920s by an Indian physicist, Chandrasekhara Raman, where light reflecting off an object carries a signature of its molecular composition and structure.

"Raman scattering has enormous potential in biological and chemical sensing, and could have many applications in industry, medicine, the military and other fields," said Stephen Y. Chou, the professor of electrical engineering who led the research team. "But current Raman sensors are so weak that their use has been very limited outside of research. We've developed a way to significantly enhance the signal over the entire sensor and that could change the landscape of how Raman scattering can be used."

Chou and his collaborators, electrical engineering graduate students, Wen-Di Li and Fei Ding, and post-doctoral fellow, Jonathan Hu, published a paper on their innovation in February in the journal Optics Express. The research was funded by the Defense Advance Research Projects Agency.

In Raman scattering, a beam of pure one-color light is focused on a target, but the reflected light from the object contains two extra colors of light. The frequency of these extra colors are unique to the molecular make-up of the substance, providing a potentially powerful method to determine the identity of the substance, analogous to the way a finger print or DNA signature helps identify a person.