Microfluidic measuring method of liquid molecular diffusion coefficient

Abstract

The invention discloses a microfluidic measuring method of a liquid molecular diffusion coefficient. The microfluidic measuring method comprises the following steps: a, separating liquid to be measured into two parts, wherein one part is raw liquid, and the other part is contrasting liquid in which 1*10<-4>-1*10<-3> g / L of fluorescent tracer is dissolved; b, respectively simultaneously injecting the raw liquid and the contrasting liquid into a chip at the same speed through a microfluidic chip sample injection port; c, after flow is stabilized, acquiring a fluorescent image of the liquid to be measured in a mass transfer process; d, defining a divergence angle theta; e, selecting data l and delta positioned on the relative concentration line on which the concentration of the fluorescent tracer is 0.6-0.8 on the fluorescent image to obtain the divergence angle theta; and f, acquiring the liquid molecular diffusion coefficient. The microfluidic measuring method disclosed by the invention is simple and convenient and higher in image data accuracy and the error can be controlled to be less than 3%. Besides, the microfluidic measuring method disclosed by the invention can be used for measuring the molecular diffusion coefficient of conventional fluid, has the advantages of low sample consumption, accurate measuring result, high analyzing efficiency and the like, is suitable for a scientific research experiment and experimental teaching.

Description

technical field [0001] The invention discloses a microfluidic test method for the diffusion coefficient of liquid molecules. Background technique [0002] The world is physical. As one of the most basic physical quantities that reveal the essence of matter, the thermophysical parameters of matter are not only the quantitative basis for measuring the performance of materials, but also important parameters for basic research, analysis calculation and engineering design of specific processes. The molecular diffusion coefficient is an important physical quantity that characterizes the diffusion and mass transfer of substances. In many transport and reaction processes, especially mass transfer processes involving diffusion control, the measurement and calculation of molecular diffusion rates are of great significance to the accurate quantification of these process engineering. For the molecular diffusion coefficient of the liquid phase, due to the close packing of the liquid mo...

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Problems solved by technology

Northeastern University has a master's thesis introducing the use of chemical chromogenic method to test the diffusion coefficient in microchannels, but there is no specific description of the experimental equipment and technology, and because the test method is too rough, the result error is large