January 22, 2021 SHARE Engineers at the McKelvey School of Engineering at Washington University in St. Louis have developed a microneedle patch that can be applied to the skin, capture a biomarker of interest from interstitial fluid and, thanks to its unprecedented sensitivity, allow clinicians to detect its presence.(Image: Sisi Cao) Blood draws are no fun. They hurt. Veins can burst, or even roll — like they’re trying to avoid the needle, too. Oftentimes, doctors use blood samples to check for biomarkers of disease: antibodies that signal a viral or bacterial infection, such as SARS-CoV-2, the virus responsible for COVID-19, or cytokines indicative of inflammation seen in conditions such as rheumatoid arthritis and sepsis.