Miniaturized Optical Device Counts Biomolecules with Advanced Image Analysis

The promise of personalized medicine involves a simple device that keeps each person apprised of their level of health, identifies even trace amounts of undesirable biomarkers in blood or saliva, and serves as an early warning system for diseases.

A device was developed that consists of an ultra-thin and miniaturized optical chip that, when coupled with a standard CMOS camera and powered by image analysis, is able to count biomolecules one by one in a sample and determine their location.

The technology is based on metasurfaces — sheets of artificial materials covered in millions of nano-sized elements arranged in a special way. At a certain frequency, these elements are able to squeeze light into extremely small volumes, creating ultrasensitive optical “hotspots.” When light shines on the metasurface and hits a molecule at one of these hotspots, the molecule is detected immediately; in fact, the molecule gives itself away by changing the wavelength of the light that hits it.

By using different colored lights on the metasurface and taking a picture each time with a CMOS camera, researchers are able to count the number of molecules in a sample and learn exactly what is happening on the sensor chip. Smart data science tools are then used to analyze the millions of CMOS pixels obtained via this process and identify trends. Researchers demonstrated the ability to detect and image not just individual biomolecules at the hotspots but even a single graphene sheet only one atom thick.

A second version of the system was developed in which the metasurfaces are programmed to resonate at different wavelengths in different regions. The technique is simpler yet is also less precise in locating the molecules.