| Microfluidic chips have broad application prospects in DNA analysis,drug screening,cell culture,biosensors and other fields.In the chip system,due to factors such as the channel connection is not tight,the presence of gas nuclei in the chip,pressure changes and other factors,air bubbles will enter the microchannel and affect the function of the chip.In recent years,scholars have proposed a variety of solutions,but the existing methods have shortcomings such as limited gas storage space,complex degassing systems,easy reintroduction of bubbles,and difficulty in integration.In this paper,based on the bubble filtration function of angiosperm pit membrane,a two-dimensional model of the fluid channel of the pit membrane was established,the mechanism of bubble filtration was studied,and a cellulose-based hydrogel was introduced to fabricate a new biomimetic microstructure unit for bubble filtration.Aiming at the bubble filtration mechanism and performance of biomimetic microstructure units,the following researches are carried out in this paper:(1)Research on the biomimetic mechanism of angiosperm pit membrane bubble filtration.The plant xylem samples were prepared and the morphological characteristics of the pit film were observed by scanning electron microscope,and the parameters such as diameter,pore size and porosity of the pit film were obtained.The surface tension of the interface resists the pressure from the bubbles,preventing the bubbles from passing through the pit membrane,and the ability to filter the bubbles is related to the surface wettability and maximum pore size of the pit membrane.The effects of wettability and maximum pore size on the filtration of air bubbles in the pit film show that the hydrophilicity of the pit film is an important factor for its ability to filter air bubbles,and the maximum pore size of the pit film is inversely proportional to the pressure when the air bubbles leak.(2)Design and manufacture of bionic microstructural units.Based on the bubble filtration principle of pit film,a biomimetic pit film based on cellulose-based hydrogel was designed.In order to integrate the biomimetic pit film into the microchannel,a micro-structural unit with limiting micro-pillars was designed;the simulation of the in-situ forming process of the biomimetic pit film showed that the shape of the limiting micro-pillars could affect the gel flow state.,among which,the circular micro-pillars can realize the in-situ molding of the biomimetic pit film;the micro-structure unit is fabricated by the micro-nano processing technology,and the biomimetic pit film is integrated into the micro-channel by the in-situ molding method,forming a bubble filter The functional biomimetic microstructural unit has a biomimetic pit film thickness of 10-50μm.(3)Bubble filtration performance detection of bionic microstructure units.The bubble filtering ability of the biomimetic microstructure unit was tested.The results showed that when the bubbles were continuously fed,the bubbles did not pass through the biomimetic pit membrane.The designed biomimetic microstructure unit had the function of filtering bubbles,and the bubble filtration rate reached 24/min when the flow rate was 4.5m L/h;In order to obtain the maximum pressure that the microstructure unit can filter bubbles,the bubble leakage threshold was tested.The bubble leakage threshold no longer increases significantly with the increase of the film thickness;the flow loss rate caused by the bionic pit film is detected,and the results show that when the film thickness is 10-50 μm,the flow loss rate is 30.76%,45.11%,and 61.26%,68.19% and 76.15%,respectively.Considering the bubble leakage threshold and the influence of bionic pit film on hydraulic transportation,the optimal thickness of bionic pit film is 20μm. |
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