Single-molecule Enzyme Assay with a Lensless Flouorestcent Imaging Device

In this paper, we report on demonstration of digital counting of enzyme based on fluorescent femtoliter droplet array imaging by using a lensless CMOS image sensor. The result supports the device can be applied to digital enzyme linked immunosorbent assay (ELISA). Digital ELISA is an ultra-sensitive detection technique for a biomarker [1, 2]. In the previous work, we developed a miniature lensless CMOS fluorescence imaging system and demonstrated to image fluorescent dye in a microchamber array [3]. In this work, we improved the device to observe fluorescent signal from single enzymes in a microchamber array. As a result, we successfully performed single-molecule enzymatic assay with the lensless device.