Fabrication of N-isopropylacrylamide (NIPAAM) based micro-hydrogel using UV LED microscope

Poly-N-isopropylacrylamide (poly-NIPAAM) has been widely used in tissue engineering and micro-structure in micro-fluidic applications. Generally, NIPAAM is polymerized and patterned by a conventional UV irradiation or UV lithography. This paper proposes a photo-polymerization method of NIPAAM using UV LED microscope. Through the combination of a commercialized UV LED, optical components, an objective lens and X-Y-Z motorized stage, we fabricated a UV LED microscope for the photo-polymerization of NIPAAM. In addition, for the investigation of the polymerization procedure, CCD camera and an illumination light source using red LED and optical components were installed. For the polymerization of NIPAAM solution, a simple micro-fluidic channel was fabricated and the NIPAAM base solution was injected into the micro-fluidic channel. If the UV LED beam was focused on the channel with NIPAAM solution, the NIPAAM can be polymerized in the focused region. Finally, we can directly fabricate micro-structures of poly-NIPAAM by using the proposed UV LED microscope.