All PDMS multi-color total internal reflection (TIR)-based devices for multi-fluorescence detection and imaging

A multi-color TIR-based device for multi-fluorescence imaging has been presented previously. Our proposed method integrated all miniaturized components, including cylindrical microlenses, prism, fiber alignment channels, into one monolithic PDMS chip, thus assembly is unnecessary, and misalignment is avoided. Here, we report new design and fabrication method of the device to improve the uniformity of the overlapped evanescent fields and thereby increase the signal to noise ratio (SNR). On the design side, we propose new method of fiber alignment and centering to facilitate the insertion of the fiber into the device and eliminate the stray rays which cause background noise. We then develop a new method to fabricate smooth Si molds used in the replication of the PDMS TIR-based devices. These steps have greatly improved the uniformity of the overlapped evanescent spots as well as the S/N ratio when imaging fluorescent dyes and beads.