Method and device for measuring concentration of substance in fluid

Abstract

A method and device for measuring a substance's concentration in a fluid. The method includes first passing a sample to be measured through a chemical sensor at least twice and recording the response value each time; forming a simultaneous equation set using the equation relation between the response value obtained during each measurement and the concentration of the substance, and the mass equation relation satisfied by the concentration change caused by a physical, chemical reaction during each measurement and by the change of the mass, electric quantity, and heat; solving for the concentration of the substance measured and the sensor calibration parameter. The method, used as an absolute measurement method, can be applied to calibrate the sample concentration of a fluid, overcomes the effects on the measurements caused by temperature, humidity, pressure, and some interfering gas, requires no sensor calibration, and substantially enhances the measurements' stability and reliability.

What is claimed is: 
     
         1 . A device for measuring material concentration in a fluid, said device comprising:
 a sample chamber;   an electrochemical sensor;   a valve; and   a pipeline,   wherein said device is configured to measure material concentration in a fluid.   
     
     
         2 . The device of  claim 1 , further comprising a pump. 
     
     
         3 . The device of  claim 2 , which consists of:
 the sample chamber, which stores a fluid sample to be analyzed;   the electrochemical sensor;   the pump;   the valve; and   the pipeline,   wherein, when the device is used for analysis of gas concentration, the sample chamber, electrochemical sensor, pump, valve, and pipeline form a circulating flow path;   wherein the sample chamber is a slender pipeline, in which a gas flows in a manner of piston flow during analysis, wherein the sample chamber has a volume greater than 95% of the total volume of the circulating flow path,   wherein the electrochemical sensor is enclosed in the circulating flow path, and is used to measure a response value and electrolyze a chemical active component to be measured; and   wherein the pump drives the fluid to circulate in the circulating flow path, so that the fluid can pass through the electrochemical sensor at least twice.   
     
     
         4 . The device of  claim 1 , wherein the valve is a three-way valve, and which device consists of:
 a piston sample chamber;   the three-way valve;   the electrochemical sensor;   a buffer chamber; and   the pipeline,   wherein the piston sample chamber, three-way valve, electrochemical sensor, and buffer chamber are connected in series through the pipeline, and   wherein one way of the three-way valve is used to receive a sample to be analyzed;   wherein the piston sample chamber stores fluid to be analyzed and drives the fluid to flow to and fro in the pipeline and the electrochemical sensor at a constant flow rate;   wherein the electrochemical sensor measures a response value and electrolyzes an electrochemical active component to be measured; and   wherein the buffer chamber is used to store the fluid.   
     
     
         5 . The device of  claim 2 , which consists of:
 the sample chamber;   a small gas chamber;   the electrochemical sensor;   the pump;   the valve; and   the pipeline,   wherein the sample chamber, electrochemical sensor, pump and valve, are connected through the pipeline to form a circulating gas path, in which the electrochemical sensor is connected in series with the pump,   wherein the small gas chamber is connected in parallel via the valve at the other end of the pump and the other end of the electrochemical sensor, and   wherein the volume of the small gas chamber is smaller than 1/10 of the volume of the sample chamber.   
     
     
         6 . The device of  claim 5 , wherein, the sample chamber is a slender pipeline, in which a gas flows in a manner of piston flow in the process of analysis, the volume of the sample chamber is greater than 95% of the total volume of the circulating flow path, and the sample chamber is used to store the fluid sample to be analyzed; the electrochemical sensor is enclosed in the circulating flow path, and is used to measure a response signal and electrolyze the electrochemical active component to be measured; the pump is used to drive the fluid to circulate in the circulating flow path, so that the fluid can pass through the electrochemical sensor at least twice. 
     
     
         7 . The device of  claim 5 , wherein, the pipeline is composed of capillary tubes. 
     
     
         8 . The device of  claim 2 , which consists of:
 the sample chamber;   a capillary tube;   the electrochemical sensor;   the pump;   the valve; and   the pipeline,   wherein the sample chamber, electrochemical sensor, pump, and valve are connected through the pipeline to form a circulating gas path;   wherein the electrochemical sensor is enclosed in the circulating flow path,   wherein the gas inlet and gas outlet that communicate with the electrochemical sensor are provided by the capillary tube, and   wherein the ratio of the cross-sectional area to the length of the capillary tube is smaller than 5% of the ratio of the apparent area of poles of the electrochemical sensor to the thickness of the gas chamber.   
     
     
         9 . The device of  claim 2 , which consists of:
 the sample chamber;   a filter;   the electrochemical sensor;   the pump; and   the valve,   wherein, the sample chamber, electrochemical sensor, pump and valve are connected through the pipeline forming a circulating flow path by the sample chamber, filter, electrochemical sensor, pump, and valve,   wherein, the sample chamber, electrochemical sensor, pump and valve are connected through the pipeline to form a circulating gas path, and   wherein the filter is connected in parallel via the valve in front of the air inlet of the electrochemical sensor in the pipeline.   
     
     
         10 . The device of  claim 2 , which consists of:
 the sample chamber;   a second sample chamber;   the electrochemical sensor;   the pump; and   valves,   wherein the sample chamber, electrochemical sensor, pump and a valve are connected through the pipeline to form a first circulating gas path,   wherein the second sample chamber, a filter, the pump and a valve are connected through the pipeline to form a second circulating gas path, and   wherein the two circulating gas paths are connected in parallel with each other.   
     
     
         11 . The device of  claim 8 , wherein:
 the sample chamber is a slender pipeline, in which a gas flows in a manner of piston flow in the process of analysis,   the volume of the sample chamber is greater than 95% of the total volume of the circulating flow path,   the sample chamber is used to store the fluid sample to be analyzed,   the electrochemical sensor is enclosed in the circulating flow path, and measures a response signal and electrolyzes the electrochemical active component to be measured, and   the pump drives the fluid to circulate in the circulating flow path, so that the fluid can pass through the electrochemical sensor at least twice.   
     
     
         12 . The device of  claim 8 , wherein, the pipeline is composed of capillary tubes. 
     
     
         13 . The device of  claim 9 , wherein:
 the sample chamber is a slender pipeline, in which a gas flows in a manner of piston flow in the process of analysis,   the volume of the sample chamber is greater than 95% of the total volume of the circulating flow path,   the sample chamber is used to store the fluid sample to be analyzed,   the electrochemical sensor is enclosed in the circulating flow path, and measures a response signal and electrolyzes the electrochemical active component to be measured, and   the pump drives the fluid to circulate in the circulating flow path, so that the fluid can pass through the electrochemical sensor at least twice.   
     
     
         14 . The device of  claim 9 , wherein, the pipeline is composed of capillary tubes. 
     
     
         15 . The device of  claim 10 , wherein:
 the sample chamber is a slender pipeline, in which a gas flows in a manner of piston flow in the process of analysis,   the volume of the sample chamber is greater than 95% of the total volume of the circulating flow path,   the sample chamber is used to store the fluid sample to be analyzed,   the electrochemical sensor is enclosed in the circulating flow path, and measures a response signal and electrolyzes the electrochemical active component to be measured, and   the pump drives the fluid to circulate in the circulating flow path, so that the fluid can pass through the electrochemical sensor at least twice.   
     
     
         16 . The device of  claim 10 , wherein, the pipeline is composed of capillary tubes.