A smartphone-based fluorescence microscope utilizing an external phone camera lens module

We constructed a smartphone-based fluorescence microscope by adding a phone camera lens module to the outside of a smartphone camera. The external lens module forms a relay system in conjunction with the built-in phone camera. The system benefits from the small pixel size of the smartphone and other advantages associated with the phone camera lens module such as its low cost, small volume, and low weight. To realize the fluorescence microscope function, the filters and illumination source were integrated into a simple mechanical structure with a focusing adjustment scheme. Based on an image analysis, the resolution of the microscope was approximately 2.5 µm and the field of view was as large as 1.2 mm×1.2 mm. The fabricated microscope was used successfully to visualize the fluorescent paint and the low concentration quantum dots on a slide glass. The microscope obtained fluorescence images of cells stained with carboxyfluorescein succinimidyl ester (CFSE). This demonstration of a smartphone-based fluorescence microscope supports the feasibility of applications such as point-of-care diagnostic equipment based on fluorescence methods.