Time is critical when diagnosing sepsis, but the tests currently used to identify this disease can take up to 72 hours. Researchers at the Laboratory of Bionanophotonic Systems (BIOS) at École Polytechnique Fédérale de Lausanne (EPFL) have developed an optical biosensor that reduces sepsis diagnosis time from several days to a few minutes. The portable biosensor is based on nanoparticle-enhanced digital plasmonic imaging.
The device employs an optical metasurface composed of a thin gold sheet containing arrays of billions of nanoholes. The metasurface concentrates light around the nanoholes to allow for precise biomarker detection. Sepsis biomarkers in a blood sample are detected using an LED and a standard CMOS camera.
To perform a test, a solution of nanoparticles, designed to capture the biomarkers, is added to the sample, and this mixture is distributed onto the metasurface. “Any nanoparticles that contain captured biomarkers are trapped quickly by antibodies on the nanoholes,” researcher Alexander Belushkin said.