A research team led by Professor Junsuk Rho from Pohang University of Science and Technology (POSTECH) has developed a new type of biosensor that can detect biomolecules using imaging technology, without the need for costly equipment like a spectrometer. The study, published in Nature Communications, involved collaborations with researchers from POSTECH and Korea University. This innovation could make advanced biomolecule detection more accessible and portable for use outside of traditional laboratory settings. Traditional optical biosensors detect biomolecules by measuring changes in light properties when molecules bind to the sensor surface. However, these systems usually require expensive and bulky equipment such as high-resolution spectrometers and broadband light sources, which limits their practical use in settings like clinics or fieldwork. The new sensor developed by the POSTECH team uses a specially designed metasurface — a structure made of nanoscale components that interact with light in unique ways. This metasurface is engineered to convert spectral information (related to different wavelengths of light) into spatial information, which can be directly read using standard imaging technology. When illuminated with a single-wavelength laser, the sensor creates a visible dark line in the image where the light interacts with the surface. When biomolecules bind to the sensor, they change the local optical properties, causing the dark line to shift. By tracking this movement, the researchers can measure molecular interactions with high precision. The sensor demonstrated excellent performance, detecting biomolecules at very low concentrations and distinguishing between specific DNA sequences. It achieved a fine resolution of about 0.1 nanometers and operated within an area smaller than a human hair. These capabilities make it promising for use in molecular diagnostics, genetic testing, and other medical applications. The system's simplicity — requiring only a compact laser and an imaging sensor — could lead to the development of portable diagnostic tools, enabling faster and more accessible medical testing in various settings.