The Research For Optical Detection System Based On Microfluidic Chip

Microfluidic chip technology becomes to be more and more mature, which has been widely used from stage of laboratory research into practical applications. Correspondingly, the microflu-idic detection technology has developed rapidly. Take the biological samples for example, this paper mainly reaches the weak signal detection system with the aid of microfluidic technology platform.Firstly, this paper studied the testing methods of the microfluidic technology. We proposed and designed a detection system combined with the fluorescence detection and absorbance detec-tion in the same device for the first time,The system can furthest extend the range of microfluidic application. In some unknown viruses or biological samples testing, you can use the absorbance scanning combined with fluorescence detection method. By this method, the sample can be iden-tified more accurately. In addition, due that the fluorescence and absorbance detection method can be realized on the same device, there is no need to change detection instruments, which can avoid the artificial operation error induced from different instruments. To eliminate the signal errors pro-duced by the microfluidic chip itself, a light path comparison detection method is proposed and the related optical system design is performed. In addition, due to ultra-short optical path (micron-level) in the absorbance detection, we introduce the second harmonic detection technology into the absorbance detection of microfluidic chip, which is proposed for the first time. Subsequently, the optical design for this system is also performed.In another part of this article, we reach the construction of the experimental system. The op-tical system structures and the circuit framework are introduced and discussed deeply. In addition, the second harmonic technique, which is closely linked with the probing sensitivity, has been an-alyzed and improved repeatedly. Experimental results show that due to elimination of error signal from material, the system with light path comparison detection method shows two or three orders higher sensitivity than that of traditional microfluidic detection technology. Additionally, due to the using of contrasting channel, the effect of intensity fluctuation of laser can be removed and the baseline of system would be more stable.On the other hand, we investigated the theory and application of second harmonic technique repeatedly.Finally, experimental results show that under the condition of no signal available using the direct absorbance method, the system still be able to detect the strong signal, which indicates the feasibility of system solutions. In a word, above results show that the system can realize the laser induced fluorescence and absorbance detection simultaneously. Especially, the absorbance on the microfluidic chip detection technology have improved prominently.