A liquid surface tension test method based on droplet mechanical vibration
A technology of liquid surface tension and testing method, applied in the field of liquid physical and chemical properties measurement, can solve the problems of error-prone, time-consuming, complicated calculation, etc., and achieve the effect of low equipment cost, less reagent consumption, and high cost performance of the instrument
Active Publication Date: 2021-03-26
TONGJI UNIV
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Problems solved by technology
The static drop method, which calculates the surface tension based on the natural shape of the droplet on a horizontal glass slide, is a static method. The traditional static drop method is based on the Laplace'sequation (Laplace's equation) in physics. The relationship between contour and surface tension is calculated, but the calculation is cumbersome, error-prone and time-consuming
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Embodiment 1
[0033] Such as figure 1 , 2 As shown, the equipment used in the present invention includes a vibration trigger device 2, and an ultrasonic probe 3 of a Doppler ultrasonic instrument is composed of an ultrasonic input module, a reflected ultrasonic detection module and a signal demodulation module, and the ultrasonic probe 3 is connected to the Doppler ultrasonic instrument. Switch 1, a hydrophobic substrate 5 is placed on the upper part of the ultrasonic probe, a micro-injector and a vibration trigger device 2 with a tip are arranged on the upper part of the hydrophobic substrate 5, the droplet 4 produced by the micro-injector has a mass of 5-20 mg, and the tip of the vibration trigger device It is made of polytetrafluoroethylene, wherein the vibration trigger device 2 is specifically composed of a steel shell and a spring, the diameter of the tip made of polytetrafluoroethylene is 100 microns, and a coupling gel layer 6 is set between the hydrophobic substrate 5 and the ultra...
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The invention relates to a liquid surface tension testing method based on mechanical vibration of a liquid droplet. The method specifically comprises the following steps: placing a hydrophobic substrate on a Doppler ultrasonic probe, and generating a liquid droplet on the hydrophobic substrate; vibrating a triggering device to freely vibrate the liquid droplet; converting free vibration of capillary waves on the surface of the liquid droplet into an ultrasonic Doppler frequency shift signal through the ultrasonic probe by using a non-focusing continuous wave Doppler method, and amplifying theultrasonic Doppler frequency shift signal; acquiring a free vibration characteristic diagram of the liquid droplet from the ultrasonic Doppler frequency shift signal by using a computer signal processing module, performing Fourier transform so as to obtain a vibration frequency characteristic diagram, analyzing the vibration frequency characteristic diagram, and reading frequency of a second harmonic generation peak; by taking the reciprocal of the mass of the liquid droplet as a transverse coordinate, and the square of the frequency of the second harmonic generation peak as a longitudinal coordinate, drawing diagrams, fitting straight lines, calculating a straight slope, and further calculating the surface tension of the liquid droplet. The method based on ultrasonic Doppler frequency shifting is capable of carrying out frequency measurement on ultrasonic signals, and has the advantages of reagent conservation, high performance cost ratios and portability.
Description
technical field [0001] The invention belongs to the technical field of measuring liquid physical and chemical properties, and in particular relates to a liquid surface tension testing method based on mechanical vibration of liquid droplets. Background technique [0002] The surface tension of a liquid is an important property of a liquid. In a normal temperature system, it can be used to determine the surface activity and calculate the adsorption amount of a surfactant on the surface of a solution. There are many methods for measuring surface tension. According to the measurement principle, it can be divided into dynamic method and static method. The dynamic method is to calculate the surface tension by measuring the value that determines a certain process, while the static method is to measure Some specific values are used to calculate surface tension. The static drop method, which calculates the surface tension based on the natural shape of the droplet on the horizontal...
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IPC IPC(8): G01N13/02
CPCG01N13/02
Inventor 张鲁凝张丽明
Owner TONGJI UNIV