Research On Fluorescence Quantitative PCR System Based On VMD-NLM

Polymerase Chain Reaction(PCR)was a technique studied in DNA and Genes to amplified specific DNA molecules.Fluorescence quantitative PCR instrument was an instrument that combined PCR technology and fluorescence quantitative analysis technology to achieve absolute quantitative detection of target DNA molecules.With the outbreak of COVID-19 around the world,in view of the fluorescent quantitative PCR instrument could detect infectious diseases effectively such as COVID-19,it had attracted widespread attention from the community.However,the fluorescent quantitative PCR instruments still had large development space in the temperature control and fluorescence signal denoising.Based on the development status of fluorescent quantitative PCR instrument in our country,this article analyzed the core technology of fluorescent quantitative PCR instrument,mainly studied the signal collection and processing problems in the fluorescence quantitative PCR system and made some improvements on temperature control algorithm.The main research contents of this paper were as follows:(1)The advantages and disadvantages of signal decomposition algorithms such as Empirical Mode Decomposition(EMD),Variational Mode Decomposition(VMD)were compared and analyzed.The VMD algorithm which had better decomposition effect was chosen in this paper.In order to solve the problem of VMD decomposition parameter tuning,the idea of the control variable method was adopted,based on the minimum of the relative entropy as the cut-off condition,the optimal ? and K were obtained.Finally,the simulation results proved that the correlation coefficient between the signal reconstructed by the optimized VMD algorithm and the original signal is the highest.(2)In order to the problem that the noise during the fluorescence signal acquisition process.This article designed a set of signals denoising algorithms and applied to the actual fluorescence signal.Based on the VMD algorithm with optimized parameters,the sample entropy is used to combine the VMD with the Non-local means(NLM)denoising algorithm.By comparing with other classic algorithms and their developed algorithms,the experimental results proved that the algorithm designed in this paper was better than other algorithm in terms of signal-to-noise ratio(SNR)and mean square error(MSE).(3)Aiming at the problems of slow temperature rise and the shortage of stability of the temperature control algorithm in the fluorescent quantitative PCR instrument.Firstly,Analyzed the system structure of the fluorescent quantitative PCR instrument.According to the requirements of PCR temperature,the fuzzy control was chosen to optimize the PID algorithm as the temperature control algorithm.Then experimental verified that the overshoot of the system in the fuzzy PID control process was smaller than the traditional PID control.The experiment results showed that compared with the traditional PID algorithm,the fuzzy PID designed in this paper took 18% less time to reach the stable temperature,and the overshoot reduced 4.5% on average.In the meantime,the VMD-NLM denoising algorithm with optimized parameters proposed in this paper had better SNR and MSE than other denoising algorithms,and the accuracy of the eigenvalue of the denoising signal was 14.39% higher than the noise signal.Experiments were carried out with different concentration samples.The linearity of the instrument is 0.9995,which was a qualified product.