New test uses coffee stains for 100x boost in disease detection

Researchers at the University of California, Berkeley have developed a novel, low-cost diagnostic test that leverages the "coffee-ring effect" to significantly enhance the sensitivity of at-home disease detection. This effect, commonly seen in coffee or wine stains where particles concentrate along the edges as a droplet evaporates, is used to pre-concentrate disease biomarkers into a ring pattern on a test membrane. By combining this natural phenomenon with plasmonic nanoparticles and an AI-powered smartphone app, the test can detect trace amounts of proteins associated with diseases such as COVID-19, sepsis, and prostate cancer within just 12 minutes—offering up to a 100-fold increase in sensitivity compared to current rapid tests. The testing process involves placing a droplet of a biological sample (e.g., nasal or cheek swab) on a membrane, where the coffee-ring effect concentrates disease markers at the edge as the droplet dries. A second droplet containing engineered nanoparticles is then added; these bind to the biomarkers