Miniaturization of Fluorescence Detection for PCR chip

In this paper, we propose a compact real time polymerase chain reaction ( PCR) system for detecting fluorescence of PCR chips. Various fluorescence detection methods have been studied, but all require many optical components and optical distances. Therefore, this paper proposes a system to detect fluorescence by attaching LED and photodiode directly to reagent surface. This system is very compact and inexpensive because it requires no optical component except only excitation and emission filters. In order to optimize the performance of the proposed system, we investigated the placement of LEDs and photodiodes, the choice of filters, the signal amplification circuit, and air bubble problems during PCR amplification. Modification of the PCR protocol to obtain better results have also been studied. PCR amplification experiments on real DNA samples showed that the proposed system works well and compactness and portability are greatly increased compared to the conventional system.