A study on the biological detection chip through the use of PDMS lens for the reinforcement of fluorescence receiving signal

Abstract

In this study, MEMS process technology is adopted to produce microfluidic chip and PDMS lens. SU-8 thick film photo resist is coated onto silicon wafer surface in two times of spin coating, then through lithography and mold transfer technology, PDMS chip of minimal line width 100 μm and thickness 200 μm is printed. In fluorescence detection aspect, we use objective lens to couple laser optical source to optical fiber, and then have it incident to excite fluorescence sample, the excited fluorescence then passes through filter and detected by optical detector of experiment group and spectrophotometer of reference group. From the experiment result, the Hex fluorescence detection limit of the system is verified to be 1 pmol/5 μl. In addition, we have integrated PDMS lens into microfluidic chip to make generalized detection experiment, it was found that the signal measured by optical embedded type is higher than that of non-embedded type. Meanwhile, the microfluidic chip with double concave lens (135°) and10 mm PDMS focusing lens can be utilized to obtain optimal fluorescence receiving effect. The fluorescence intensity is raised by 2–3 times, and the measurement limit is lowered to 100 fmol/5 μl.