Some optical sensing chip designs contain nearly as small nanostructures as the biological and chemical molecules they’re searching for. These nanostructures improve the sensor’s ability to detect molecules. But their diminutive dimensions make it difficult to guide the molecules to the correct area of the sensor.
Researchers have created a new sensor that aims at this problem. The sensing chip uses surface-enhanced infrared absorption (SEIRA) spectroscopy. The new sensor consists of several arrays of tiny rectangular strips of gold. The researchers dipped the strips in 1-octadecanethiol, a chemical compound (often abbreviated as ODT) that they chose to identify. Researchers then added a drop of liquid metal — in this case, gallium — to serve as the sensor’s base. Lastly, they placed a thin glass cover on top to form a sandwich-like structure.
The design of the sensing chip, with its layers and cavities, creates what researchers call a “nanopatch antenna.” The antenna funnels molecules into the cavities and absorbs enough infrared light to analyze biological and chemical samples.