Wearable Label-Free Optical Biodetectors: Progress and Perspectives

Biomarkers are the primary indicators of human health. Measurements traditionally rely on targeted binding and assays, which, in turn, rely on specific “labels” that define the biomarker or molecule of interest. While selective and specific, label-based approaches limit the range of biomarkers a technology can detect. Technologies that can detect and analyze a broad range of biomarkers offer versatility, especially rapid repurposing for new targets. Optical technologies for label-free biomarker sensing enable noninvasive, minimal-contact, and wearable or point-of-care rapid diagnostic measurements. Herein, label-free biomarker detection is reviewed with an emphasis on progress toward miniaturized and noninvasive wearable devices. Compact light-emitting devices and optical detection technologies are presented, tailored for a large range of biomarkers, including recent advances in battery-free devices. Label-free detection is reusable, reagent-free, and allows continuous long-term monitoring. The potential for optical technologies for label-free detection in terms of integration, device design, and future applications is summarized.