Fast, accurate nanoscale sensor created

Optokey, a startup based in Hayward, California, has developed a miniaturized sensor based on Raman spectroscopy that can quickly and accurately detect or diagnose substances at a molecular level. "Our system can do chemistry, biology, biochemistry, molecular biology, clinical diagnosis, and chemical analysis," said company president and co-founder Fanqing Frank Chen. "And our system can be implemented very cheaply, without much human intervention."

The technology is based on surface-enhanced Raman spectroscopy, a technique for molecular fingerprinting. While SERS is a highly sensitive analytical tool, the results are not easily reproducible. As a scientist at Berkeley Lab, Chen and colleagues developed a solution to this problem using what they called "nanoplasmonic resonators," which measures the interaction of photons with an activated surface using nanostructures in order to do chemical and biological sensing. The method produces measurements much more reliably.

"At Optokey we're able to mass produce this nanoplasmonic resonator on a wafer scale," Chen said. "We took something from the R&D realm and turned it into something industrial-strength."

The miniaturized sensors use a microfluidic control system for "lab on a chip" automated liquid sampling. The company is taking a page from the semiconductor industry in making its chip. "We're leveraging knowledge acquired from high-tech semiconductor manufacturing methods to get the cost, the volume, and the accuracy in the chip," said VP of Manufacturing Robert Chebi, a veteran of the microelectronic industry who previously worked at Lam Research and Applied Materials. "We're also leveraging all the knowledge in lasers and optics for this specific Raman-based method."

Chebi calls Optokey's product a "biochemical nose," or an advanced nanophotonic automated system, with sensitivity to the level of a single molecule, far superior to sensors on the market today. "Today's detection and diagnosis methods are far from perfect -- detection limits are in PPM (parts per million) and PPB (parts per billion)," he said. "Also, our system can provide information in minutes, or even on a continuous basis, versus other methods where it could take hours or even days, if samples have to be sent to another lab."

The potential applications, he says, are vast, including food safety, environmental monitoring (of both liquids and gases), medical diagnosis, and chemical analysis. Optokey's customers include a major European company interested in food safety, a Chinese petrochemical company interested in detecting impurities in its products, and a German company interested in point-of-care diagnosis.

"I think we're at the cusp of a really major transition in the field," Chen said. "The product we're envisioning is something that is compact and automated but also connected, and it can go into schools, restaurants, factories, hospitals, ambulances, airports, and even battlefields."

The next market Chen is targeting is the smart home, where a nanophotonic sensor could be built to scan for pollutants not just in food but also in air and water.

Trained at Los Alamos National Laboratory and Mount Sinai Hospital at NYU, Chen started out as a biochemist working on biomedical devices. After he joined Berkeley Lab around 2000, he learned about quantum dots, which are nanocrystals with peculiar properties, and began exploring their use in biology. That led to further investigations into nanomaterials. One accomplishment was a so-called molecular ruler made of gold nanoparticles tethered to DNA strands, which, using plasmon resonance, was capable of measuring protein-DNA interactions.

Ultimately Chen and his group developed about 20 patents involving hybrid bionanomaterials. The key discovery that led to the formation of Optokey was the development of the nanoplasmonic resonators to dramatically improve the signal and reliability of Raman spectroscopy. The method was initially used in the research lab to quickly and accurately detect a biomarker for prostate cancer, which has a high rate of false positives using conventional diagnostic tools.

Optokey is a privately held company with about 10 employees. Besides Chen, the other co-founder is Richard Mathies, a UC Berkeley chemistry professor and world-renowned expert on Raman spectroscopy. The company was formed in 2010, and operations were launched in 2013.

"There was 10 years of research that went into this, funded by NIH, DARPA, the federal government, private foundations," said Chen. "Berkeley Lab has a really good culture of multidisciplinary research, excellent engineering, and very strong basic science. Plus it has strong support for startups."