Research On Helicobacter Pylori Detection Based On Wavelength Modulation Spectroscopy

Helicobacter pylori(Hp),the most common human known pathogen,is a helical,micro-perfused Gram-negative bacterium that was first reported by Australian scientists Barry Marshall and Robin Warren.They isolated successful bacteria from gastric mucosal biopsies of patients with chronic active gastritis and are the only known microbial strains that can survive in the human stomach.Hp has a strong pathogenicity;which is the main causative agent of gastric ulcer and duodenal ulcer,and is closely related to the onset of gastric cancer.The World Health Organization's cancer research machine also constructs it as I Class carcinogen.In clinical applications,the detection of Hp has two main categories:invasive detection and noninvasive detection.Invasive testing is a method that needs biopsy tissue in the patient's gastric mucosa to be tested as a test material through an endoscope.This method will bring great suffering to patients,its main include:biopsy urease and bacterial culture method.Non-invasive detection does not rely on gastroscopy,can be detected by collecting the patient's breathing gas,blood or stool,the patient painless,is commonly used in recent years detection methods,which include:serum antibody testing and respiratory gas detection.As a new detection method,the respiratory gas detection has high sensitivity and specificity,which is the "gold standard" for modern Hp medical detection.As a mature trace gas detection technology,Tunable Diode Laser Absorption Spectroscopy(TOLAS)has many advantages,such as high sensitivity,fast response and real-time detection,which has been widely used in many fields.The main objective of this study was to combine TDLAS with respiratory gas detection technology to develop a real-time,on-line,portable,and rapid Hp respiratory gas detection device.In order to clear the research content and well purpose,the beginning of this paper describes the basic theory of respiratory gas detection,discusses the basic principles of TDLAS,and gives the relevant characteristics of them.Then through computer simulation of TDLAS temperature and pressure,which are main experimental conditions in measurements,and selecting the best conditions for experimental measurements.Secondly,through the theoretical analysis and data simulation,we choose the CO2 absorption line with the wavelength between 4975cm-1 and 5000cm-1,and select the absorption line in this range.We choose "P16e" and "R17e" absorption line,their wavelength are 4978.022 cm-1 and 4978.204 cm-1,respectively.Finally,after completing the above work,we developed a set of Hp breathing gas detection prototype based on TDLAS,which includes laser,gas cell,photodetector and lock-in amplifier.The prototype has varieties of advantages,such as simple operation,high detection sensitivity,low cost,real-time monitoring,good stability.At the same time,the prototype was applied to Jinhua Guangfu Hospital and Jinhua Central Hospital for actual measurement and analysis,and obtained relatively good experimental results.The experimental results show that:in the detection of positive results,Hp respiratory gas testing prototype and the current measurement equipment test results are the same.Making a good foundation for research and application in the future,TDLAS can reach a higher level.