A team led by Liwei Lin, a CITRIS PI and professor of mechanical engineering at UC Berkeley, is transforming rapid at-home tests to detect viruses like COVID-19 with up to 100 times more sensitivity. Their biosensing technology combines natural liquid evaporation processes with plasmonics— the nanoscale manipulation of optical signals at metal-dielectric interfaces — and artificial intelligence (AI) to enable low-cost, accessible diagnostics.
The work stems from a CITRIS COVID-19 Award and centers on a phenomenon called the “coffee ring effect,” which describes a liquid droplet’s tendency to push suspended particles outwards as it evaporates, creating a rim of concentrated particles. A droplet from a cheek or nasal swab placed on a membrane will follow the same process, leaving a ring where disease biomarkers may be easily found. Plasmonic nanoparticles engineered to stick to disease biomarkers are then added to the membrane, resulting in a visually observable change if the test is positive.
Based on their prototype — a home testing kit made of 3D-printed components that gives results in less than 12 minutes — the team plans to expand rapid testing to other life-threatening conditions such as prostate cancer and sepsis, which both contain biomarkers that the technology can detect. Researchers aim to improve people’s ability to regularly screen for infectious diseases, intercept time-sensitive conditions such as sepsis sooner, and make health care more equitable in low-resource settings.