Research On Online Detection Technology Of Chinese Medicine Moisture Based On Near Infrared Spectroscopy

As one of the precious crystallization in the evolution and development of Chinese civilization,the demand of TCM in China and even the whole world has been expanding and increasing,and its application and popularity in the international community have been further expanded and improved.However,at present,there are still many key problems in the quality consistency management of TCM products,among which,the measurement of water content in the pharmaceutical process of TCM products is one of the important links in the quality consistency management of TCM products.An on-line sensor of water content in traditional Chinese medicine based on near infrared light emitting diode(LED)excited by square wave is developed by using near infrared absorption spectroscopy and square wave signal which has rich characteristic information in time and frequency domain.The main work is as follows:1.Starting from the basic theory of NIR spectroscopy technology,this paper introduces the principle of NIR absorption spectroscopy,analyzes the acquisition methods of NIR signal of different forms of samples,and investigates the development status of online detection technology of TCM moisture content at home and abroad,which provides a theoretical basis for this study.2.The optical part of the sensor is designed.According to the absorption of water molecules in the near infrared wave band line position,and LED the transmitted power,transient response,such as working parameters,the sensor is optimized and the selection of light source and detector,according to the selected light source driving the other wave excitation signal parameters are optimized,the optimization of square wave parameters,and designed a frustum of a cone type sensor shell,according to the LED exit divergence Angle of light determines the installation Angle,to ensure that the spectrum signal is the high efficiency collection.3.Sensor peripheral circuit design.According to the working conditions of LED,a constant current source circuit with ultra-low ripple noise is designed.According to the working principle of the photoelectric diode is designed with a level of low frequency high-pass filter and offset voltage of the photoelectric detector signal processing circuit,and the bias circuit to the single chip microcomputer(MCU)for analog signal acquisition,designed a second-order active low-frequency filtering processing circuit and a high frequency of passive filter processing circuit has successfully built a band-pass filter circuit,the spacecraft simulation signal filter,secondary data-processing significantly improves the signal-to-noise ratio of the analog signal detector.4.Research on software algorithms.In this paper,a square wave excitation method is proposed to drive the LED,and the response signal of the detector is the square wave signal carrying the information of the water content of Chinese medicine.The wavelet transform method is used to filter the detector signal after the analog-to-digital converter(ADC),and the ripple noise of the response signal of the detector is greatly suppressed.In order to extract the characteristic quantity related to the information of TCM water content more conveniently,the fast Fourier exponential transform(FFT)analysis algorithm was used to transform the filtered digital signal with the information of TCM water content from time domain to frequency domain,and the characteristic quantity was extracted from the perspective of frequency domain.Principal component analysis(PCA)algorithm is used to analyze the main harmonic components related to the water content of traditional Chinese medicine in the frequency domain,which greatly improves the sensitivity and accuracy of the sensor.5.Quantitative measurement experiment of water content of TCM.The experimental sample was Tutong pill provided by Jiangxi University of Traditional Chinese Medicine.The drying method prescribed in Chinese Pharmacopoeia and the sensor studied in this paper were compared and tested.Eight groups of experimental samples with different water content were used to calibrate the sensor.The water content and the extracted feature were fitted linearly.The fitting linearity of spectrum analysis and PCA algorithm were0.992 and 0.993,respectively.Compared with the drying method,the maximum relative error is less than 7.7%,and the minimum relative error is 1%,which indicates that the water content sensor of Chinese medicine studied in this paper has a certain application prospect.