A simple fabrication and integration technique of microlens for microfluidic lab-on-a-chip by overflow of UV resin through holes

In the present study, a simple fabrication technique for microlens or microlens array is proposed based on an overflow of a UV curable resin through micro-holes followed by photopolymerization of the resin. As a first step of the present technique, a micro-hole is precisely drilled on a flat plastic sheet. A UV curable resin is carefully spread over another plastic sheet, and then an overflow process is carried out by compressing the spread resin with the holed sheet. The overflowed resin through the hole is then cured by irradiation with UV light and consequently, the microlens is formed from the overflowed resin on the holed sheet. By utilizing the present fabrication technique, microlenses of 600 and 750 μm in diameter were successfully manufactured. The fabricated microlens was also characterized by measuring its detailed dimensions and focal length. The microlens of 750 μm in diameter showed a smooth convex surface and the focal length of 2.11 mm.