Study On Efficient Biological Microfluidics Pumping Based On Alternating Current Electrothermal

In recent years,large-scale spread of AIDS,avian influenza,yellow fever and other infectious diseases cause great losses to people's lives and properties.Conventional methods of medical and biological detection,which is time consuming,quite complicated,expensive and insensitive,is unfavourable to the early diagnosis and intervetion of the infectious disease and aggravates its perniciousness.Therefore,it is of great clinical significance to develop a kind of simple,rapid and accurate detection aiming at pathogens.Microfluidic technology has low sample consumption and high throughput.with the advantages of high degree of miniaturization,integration,portability,microfluidics can conquer the weakness of conventional detection methods and achieve rapid and accurate detection of pathogens.In the process of detection of any kind of pathogens,it is the first step to drive the sample of biological fluid containing the pathogens?such as blood?and complete biological fluid sample injection,after which the subsequent operation of detection is conducted.As a result,it is of great significance to drive the sample of biological fluid in a rapid,convenient and efficient way for detection in microfluidic chips.This paper studied the micropump technology based AC electrothermal phonomenon.An electric field is applied to the electrodes under micrometre scale,so that the fluid in the micro channel can be moved by the electric field force,and the pumping of the high conductivity fluid can be realized.The related theory of AC electrothermal is studied.The volume force under AC field,namely AC electric field force under linear model and strong coupling model of high conductivity fluid respectively,is deduced.The difference of thermal fields under linear model and strong coupling model separately are compared,Through two-dimensional simulation,under the strong coupling model,the optimal parameters and the pump velocity sheets of different voltage and frequency of the AC electrothermal micropump are obtained.The simulation result shows that when applied an alternating voltage of 15V_pp,the fluid,of which the conductivity is 0.1S/m,0.2S/m,0.3S/m,0.4S/m,0.5S/m and 0.6S/m separately,has the maximum velocity of 930.93?m/s,1634.4?m/s,1979.7?m/s,2000.7?m/s,1956.5?m/s and 1924.4?m/s separately.According to the parameters of the micropump obtained by simulation,the micropump for experiments was fabricated.Based on the experimental study of the flow field,the experimental phenomena under different voltages and frequencies are observed.The influence of the voltage and the frequency is analyzed.The experiment result shows that when the frequency is lower than 1MHz,bubbles will occur in the channel of the micropump and the lower the frequency is,the more bubbles occur.Bubbles are obstacles for pumping,so the AC electrothermal micropump should be operated at low frequencies.The AC electrothermal micropump can be used for fast injection of high conductivity fluid,and has wide application prospects in the fields of biology and medicine.