The Design Of Electronic Nose Instrument For Lung Cancer Breath Diagnosis

Lung cancer is the leading cause of cancer death in both men and women, and badly threatens the health of human .The diagnosis in the early stage is the key to decrease the rate of death caused by lung cancer .Presently, there is no routine and simple instrument to diagnose early lung cancer in the clinic .Breath diagnosis is a novel and non-invasive technology and reflects the metabolism change of tissue by detecting the VOCs in the patient's breath gas. The e-nose is convenient. In this dissertation we propose a novel e-nose based on a kind of virtual array of surface acoustic wave (SAW) gas sensors and an imaging recognition method to diagnose lung cancer.The main research content of this work:According to the foreign research, the breath gas of lung cancer patient contains the marker VOCs .We choose the SAW gas sensor and design the detecting circuit. Its sensitivity to mass change can reach 1 KHz/ng .We propose a novel e-nose based on a kind of virtual array of surface acoustic wave (SAW) gas sensors and an imaging recognition method, and design the structure of the instrument, which contain several parts, such as collection and pretreatment system, separation system, detecting system, data analysis and communication system, diagnosis software .We demonstrate every system and design the gas path.We design and implement the hardware and software of this instrument, resolve the nonlinearity of Pt100 resistance using least square fitting method , accurately control temperature using PID arithmetic . The circuit of the e-nose was calibrated by standard methods and the calibration components. MSP430 is the controlling core in the lower computer and the instrument is controlled by manipulating the upper computer's software. We study and design a diagnosis system.This instrument is used in the clinical application. Using the e-nose to detect lung cancer patients and healthy persons, the results is fine. The research produces a relatively noninvasive tool effective in diagnosing lung cancer at an early and potentially curable stage. These breath biomarkers may eliminate the need for additional and often more invasive diagnostic tests that are costly, incur risk, and prolong the diagnostic evaluation of people with suspicion of lung cancer and can provide public health benefit by saving lives.