Ultra-low concentration gas sensor

Abstract

The invention discloses a sensor for detecting ultra-low concentration gas. The sensor detects analyzed gas under the conditions of constant pressure, constant flow, constant humidity, constant temperature and being free from influence of interfering gas, which maximally eliminates interference of change factors such as gas flow, pressure, humidity, temperature, gas composition and the like, improves signal-to-noise ratio of the sensor, and reaches detection limit and precision of 1-10ppb. The sensor comprises a gas filter, a constant-flow and constant-pressure device, a constant-humidity andconstant-temperature device and a detector, wherein, the gas filter is used for reducing particles and the interfering gas which generates ppb-order or greater signal interference on a detection signal of detected gas carried in a gas sample; the constant-flow and constant-pressure device is connected to the gas filter and controls flow velocity and pressure of the filtered gas; the constant-humidity and constant-temperature device is connected to the constant-flow and constant-pressure device, controls the humidity at a constant state for the detection signal of the detected gas or eliminates influence of the humidity through zero-point correction, and controls the temperature of the gas; and the detector is placed in the constant-humidity and constant-temperature device and is used for detecting the gas.

Description

technical field [0001] The present invention relates to the field of gas sensors, more particularly, to a gas sensor for detecting gases with a concentration lower than 100 ppb in the environment or exhaled air. Background technique [0002] Gas detection in the field of environment and health and safety usually needs to achieve the detection limit and accuracy of the concentration lower than 1-100ppb. For example, in order to prevent poisoning or ensure health and safety, the concentration of benzene and formaldehyde in the living environment must not exceed 100ppb; and for the diagnosis of asthma and other respiratory diseases, the detection limit and accuracy of the concentration of nitric oxide in exhaled breath must reach 1-5ppb. At present, the technologies that can detect these ultra-low concentration gases are mainly expensive large-scale laboratory analysis instruments. However, cheap and portable sensor detection instruments that can be used for on-site detection ...

AI Technical Summary

Problems solved by technology

The noise superimposed on the detection signal cannot be removed or identified by the circuit, but will be amplified with the amplificatio

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