MEMS 와 thermal imprinting 기반의 플라스틱 표면 거칠기 조절과 이에 따른 형광 신호향상에 관한 연구

Abstract

The development of novel methods for rapid, low cost and high sensitivity biochip attracts particular interests because of their wide applications in medical diagnosis, food inspection and biomedical research. Fluorescence has long been used in bio technology due to its advantages such as high sensitivity, easy handling, lower cost and large dynamic range detection. There have been numerous studies in the literature regarding the enhancement of fluorescence signals by resonant coupling between excitations and surface plasmon of metal, nano particle for high sensitivity of an immune reaction by increasing surface roughness for high sensitivity and reliability. But these methods require complicated structure, delicate manipulation, high cost, requiring long time and low reliability. So, there have been problem in applying those methods for the mass production of plastic bio chip. Thus, in the present work, we are introducing a simple process to enhance the fluorescence through the control of surface area by controlling roughness of plastic biochip. This method can also be applied to various detection methods such as fluorescence, Raman and micro fluidic method. In our study, stainless steel (SUS 304) based metal mold was fabricated by modified MEMS process. The surface of stainless steel was controlled by 2-step etching process. In the first step, the metal substrate was electrochemically etched in H2SO4 and H3PO4 electrolyte with electric charge to fabricate mold which has fine structure. In the second step, the surface was treated with FeCl3 in wet chemical etching process for various times at room temperature to control the surface roughness. Then, COC based plastic biochip of various thicknesses was fabricated from 304 SS mold using imprinting technique and the effect of surface roughness of COC biochip on the enhancement of fluorescence intensity was investigated via CY5 dye molecule and flurimmuna assay. The studies show that fluorescence intensity increases with surface roughness without much change in the auto-fluorescence. The process proposed in this technique is simple, low cost and highly sensitive for protein detection.