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学者姓名：王志海
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摘要 ：
Micro-droplet generation for solid particle suspensions is studied experimentally over a wide range of volume fraction of solid (q), using a home build pneumatic ejection system. Ejection is actuated by a solenoid valve, setting to "conduction" state for short period of time At. Pressurized gas of Po enters the reservoir, creating a pressure pulse P(t), forcing the liquid out via a tiny nozzle to produce a micro-droplet. Here, P(t) is measured by a high-speed sensor, and the ejection process is examined by high speed photography and image processing. Single droplet can be ejected for suspensions with 11 up to 33%. For q less than about 18%, the required pressure amplitude increases roughly linearly with 'i" With 'I increased above 18%, the demand for pressure amplitude is significantly higher than the linearly increasing trend. Especially as q is increased above 24u/0, the liquid band stretches much longer, and the break-up is delayed drastically.
关键词 ：
micro-droplet micro-droplet particulate suspension particulate suspension pneumatic pneumatic
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| GB/T 7714 | Bao, Weijie , Sun, Shengnan , Wang, Zhihai et al. Micro-droplet of Particulate Suspension Generated by a Pneumatic Ejection System [C] . 2021 : 904-908 . |
| MLA | Bao, Weijie et al. "Micro-droplet of Particulate Suspension Generated by a Pneumatic Ejection System" . (2021) : 904-908 . |
| APA | Bao, Weijie , Sun, Shengnan , Wang, Zhihai , Wang, Yaohong . Micro-droplet of Particulate Suspension Generated by a Pneumatic Ejection System . (2021) : 904-908 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Micro-droplet ejection is a liquid dispensing technology that has potential applications in many fields. Specifically, pneumatic ejection is actuated by a solenoid valve, which is set to 'conduction' state for a brief period of time Delta t. High pressure gas of P-0 enters the liquid reservoir, then releases through a venting tube, creating a oscillating pressure waveform P(t), forcing the liquid out through a tiny nozzle to form a micro-droplet. For each actuation, P(t) is acquired by a high-speed pressure sensor, and the ejection state is obtained by high-speed photography and image processing methods. Some issues for the design of pneumatic micro-droplet ejector are discussed. For simulation of P(t), it is proposed within an electro-acoustic analogy picture that the acoustic resistance of the venting tube is mainly due to viscous effect and may vary with time during the whole ejection process. Based on this assumption, the calculated P(t) is more consistent with the actual measurement. Experimentally, the droplet ejection process for different length of venting tube is studied. With P-0 and Delta t set, by increasing the venting tube length L, both the peak value P-MAX1 and duration of the first positive pressure period increase, and more droplets are ejected from a single actuation. By setting different P-0, P-MAX1 for different L is tuned to an identical and appropriate value, so that single droplet is ejected due to the first positive pressure period. However, with the increase of L, the peak value of the second positive pressure period P-MAX2 increases. There is a certain probability that another droplet is ejected. It is realized that the increase of L can reduce gas consumption, but the multiple ejection is a drawback that should be considered in the design of pneumatic ejection system.
关键词 ：
micro-droplet micro-droplet electro-acoustic analogy electro-acoustic analogy image processing image processing pneumatic pneumatic
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| GB/T 7714 | Bao, Weijie , Wang, Yiwei , Yang, Baojun et al. Some considerations for designing a pneumatic micro-droplet generator [J]. | JOURNAL OF MICROMECHANICS AND MICROENGINEERING , 2021 , 31 (4) . |
| MLA | Bao, Weijie et al. "Some considerations for designing a pneumatic micro-droplet generator" . | JOURNAL OF MICROMECHANICS AND MICROENGINEERING 31 . 4 (2021) . |
| APA | Bao, Weijie , Wang, Yiwei , Yang, Baojun , Wang, Zhihai , Wang, Yaohong . Some considerations for designing a pneumatic micro-droplet generator . | JOURNAL OF MICROMECHANICS AND MICROENGINEERING , 2021 , 31 (4) . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Electric field-assisted fused deposition modeling (E-FDM) is a promising technique in the field of 3D printing. This paper studies the start-up stage of the printing, which is a process of liquid gradually deforming and making an initial contact with the substrate under the action of electric stress. Polycaprolactone, a popular material for biomedicine, is selected as the printing material. With a home-built E-FDM system, the nozzle-to-substrate distance and the nozzle and substrate temperatures are all held steady. With a photography system, the process of meniscus deformation is recorded. And by image processing methods, the meniscus length and the volume of liquid at the nozzle can be obtained. At a set of initial liquid volumes (V-i), nozzle voltage is ramped to a fixed value at a fixed rate. The effects of V-i on the meniscus deformation during the start-up stage of the printing are examined. For sufficiently small V-i, the meniscus deforms into a conical (Taylor cone) shape, and a fine jet with a diameter much smaller than the nozzle diameter appears. For sufficiently large V-i, the meniscus exhibits a spindle shape when it touches the substrate. At an intermediate V-i, a Taylor cone is formed, tending to eject a fine jet. After a short period of stagnation or even a slight retraction, no liquid is emitted. Through this study, it is suggested that for high-resolution printing, ramping the voltage at small V-i may be preferable. This proposition is preliminarily confirmed in a direct writing test.
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| GB/T 7714 | Xu Ruihan , Bao Weijie , Wang Zhihai et al. Start-up stage with improved resolution for an electric field-assisted fused deposition [J]. | RSC ADVANCES , 2021 , 11 (13) : 7397-7404 . |
| MLA | Xu Ruihan et al. "Start-up stage with improved resolution for an electric field-assisted fused deposition" . | RSC ADVANCES 11 . 13 (2021) : 7397-7404 . |
| APA | Xu Ruihan , Bao Weijie , Wang Zhihai , Wang Yaohong . Start-up stage with improved resolution for an electric field-assisted fused deposition . | RSC ADVANCES , 2021 , 11 (13) , 7397-7404 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Sample deposition based on micro-droplet ejection (MDE) has broad application prospects in the field of biomedicine. As a potential technology option for cell printing, a hybrid pneumatic-electrohydrodynamic (HPEHD) MDE system is built in the laboratory. Strong electric field is established by applying a high voltage between the nozzle and a collector electrode. The pneumatic actuation is realized via a solenoid valve staying outside of the liquid chamber. The solenoid valve is set in conduction for a short period of time Delta t; gas of high pressure P-0 enters the liquid chamber, and produces a pressure pulse, which extrudes the liquid slightly out of the nozzle. The liquid is deformed further in the electric field into a cone shape (Taylor cone), and then the end of the Taylor cone breaks to form a micro-droplet. The ejection process is studied using machine-vision and image processing. With sodium alginate (1.0%) as bioink, single droplet per ejection is realized, and the droplet size is reduced by 50% due to the presence of the electric field. It is found that increasing the voltage has little effect on the size of droplets. In contrast, increasing source pressure P-0 or increasing Delta t the conduction time of the solenoid valve can change the volume of droplet in a wider range.
关键词 ：
electrohydrodynamic electrohydrodynamic pneumatic pneumatic on-demand on-demand micro-droplet micro-droplet
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| GB/T 7714 | Wang, Yiwei , Bao, Weijie , Wang, Fei et al. Generation of micro-droplet on demand with reduced sizes by a hybrid pneumatic electrohydrodynamic method [J]. | JOURNAL OF MICROMECHANICS AND MICROENGINEERING , 2020 , 30 (3) . |
| MLA | Wang, Yiwei et al. "Generation of micro-droplet on demand with reduced sizes by a hybrid pneumatic electrohydrodynamic method" . | JOURNAL OF MICROMECHANICS AND MICROENGINEERING 30 . 3 (2020) . |
| APA | Wang, Yiwei , Bao, Weijie , Wang, Fei , Zhang, Haiyi , Wang, Zhihai , Wang, Yaohong . Generation of micro-droplet on demand with reduced sizes by a hybrid pneumatic electrohydrodynamic method . | JOURNAL OF MICROMECHANICS AND MICROENGINEERING , 2020 , 30 (3) . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Micro-droplet generation is related to liquid dispensing technology that has potential applications in many fields. Specifically, pneumatic micro-droplet generation is controlled by a solenoid valve being briefly turned on, so that high pressure gas enters the liquid reservoir, forming a gas pressure pulse waveform P(t), forcing the liquid out through a tiny nozzle to form a micro-droplet. For each ejection, P(t) is acquired by a high speed pressure sensor, and the ejection state is obtained by machine vision methods. A prediction model based on BP neural network is established, with P(t) as input and the droplet ejection state as output. Experiments show that the BP neural network can predict the number of droplets with an accuracy higher than 99%. It is also shown that the BP neural network can improve the prediction accuracy for the position of droplets relative to the nozzle, at a given moment. Under typical working conditions, P(t) is not consistent. As a result, the ejection state is not consistent either. These prediction models may be used for real time monitoring and control of the pneumatic micro-droplet generator.
关键词 ：
Pneumatic Pneumatic BP neural network BP neural network Ejection state Ejection state Micro-droplet Micro-droplet Machine vision Machine vision
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| GB/T 7714 | Wang, Fei , Bao, Weijie , Wang, Yiwei et al. Ejection state prediction for a pneumatic micro-droplet generator by BP neural networks [J]. | JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING , 2020 , 14 (1) . |
| MLA | Wang, Fei et al. "Ejection state prediction for a pneumatic micro-droplet generator by BP neural networks" . | JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING 14 . 1 (2020) . |
| APA | Wang, Fei , Bao, Weijie , Wang, Yiwei , Wang, Xiaoyi , Ren, Keyan , Wang, Zhihai et al. Ejection state prediction for a pneumatic micro-droplet generator by BP neural networks . | JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING , 2020 , 14 (1) . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Pneumatic micro-droplet ejection is a printing technique that has potential applications in many fields, especially in the field of bio-printing. The ejection is via a solenoid valve being briefly turned on, so that high pressure gas enters the liquid reservoir, forming a gas pressure pulse, forcing the liquid out through a tiny nozzle to form a micro-droplet. For bio-printing applications, the bio-inks are typically non-standard. The difficulties are not only that the initial working parameters are difficult to set, but also the working conditions change over time in many cases. In order to maintain a stable single-drop ejection state, a machine vision based ejection monitoring was designed to obtain the number, positions and sizes of the droplets for each ejection, and a feedback control is realized by adjusting the "ON" time of the solenoid valve or the gas pressure at the front end of the solenoid valve.
关键词 ：
Micro-droplet Micro-droplet Machine vision Machine vision Pneumatic Pneumatic Feedback control Feedback control
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| GB/T 7714 | Wang, Fei , Wang, Yiwei , Bao, Weijie et al. Controlling Ejection State of a Pneumatic Micro-droplet Generator Through Machine Vision Methods [J]. | INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING , 2020 , 21 (4) : 633-640 . |
| MLA | Wang, Fei et al. "Controlling Ejection State of a Pneumatic Micro-droplet Generator Through Machine Vision Methods" . | INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING 21 . 4 (2020) : 633-640 . |
| APA | Wang, Fei , Wang, Yiwei , Bao, Weijie , Zhang, Hui , Li, Jiangeng , Wang, Zhihai . Controlling Ejection State of a Pneumatic Micro-droplet Generator Through Machine Vision Methods . | INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING , 2020 , 21 (4) , 633-640 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Sample deposition based on micro-droplet ejection has broad application prospects in the field of biomedicine. Ejection of RPMI-1640 culture medium (without cells) is investigated experimentally using a home-build electrohydrodynamic (EHD) ejection system, consisting of a liquid supplier and a nozzle, a voltage source, a droplet collector, and a supplemented photoelectric monitoring module. Electric voltage is applied between the nozzle and the droplet collector. The liquid surface is electrically charged and the ejection takes place when electric force overcomes the surface tension. At appropriate voltages, uniform ejection states are established with ejection frequency ranging from a few to a few tens of Hertz. Monitoring of the ejection process is performed by two methods. The ejection process can be recorded by a high speed camera, and then analysed by image processing. Using output signal of a charge amplifying circuit as a reference, a single shot camera is controlled to capture images at certain delays, anti the entire process of the droplet ejection can be recorded. Experiments have shown that when the liquid meniscus breaks up, the output signal of the charge amplifier reaches the maximum.
关键词 ：
charge-amplifier charge-amplifier electrohydrodynamic electrohydrodynamic micro-droplet micro-droplet single shot camera single shot camera
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| GB/T 7714 | Jia, Ruiwen , Zhang, Haiyi , Wang, Can et al. Vision based Studies of Electrohydrodynamic Ejection Process [C] . 2019 : 2204-2208 . |
| MLA | Jia, Ruiwen et al. "Vision based Studies of Electrohydrodynamic Ejection Process" . (2019) : 2204-2208 . |
| APA | Jia, Ruiwen , Zhang, Haiyi , Wang, Can , Wang, Fei , Wang, Yiwei , Deng, Hanchen et al. Vision based Studies of Electrohydrodynamic Ejection Process . (2019) : 2204-2208 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Sample deposition based on micro-droplet ejection has broad application prospects in the field of biomedicine. Ejection of RPMI-1640 medium (with and without cells) is investigated experimentally using a home-build electrohydrodynamic (EHD) ejection system, consisting of a liquid supplier and a nozzle, a high voltage source, a droplet collector, and a high speed photography module. High electric voltage is applied between the nozzle and the droplet collector. The liquid surface is electrically charged and the ejection takes place when electric force overcomes the surface tension. The ejection process is studied by using high speed photography and image processing. At low voltage, a stable ejection state is established with ejection frequency ranging from a few to a few tens of Hertz. At high voltage, another stable ejection state is reached with ejection frequency as high as 1300Hz. At the transition voltage range, the ejection exhibits a periodic behaviour. During each cycle, the meniscus rapidly oscillates with gradually increased amplitude, and with several non-uniform droplets ejected at the final stage of the cycle. Human peripheral blood mononuclear cells, after ejection, shows survival rates higher than 79%, manifesting EHD ejection as a promising technique for cell printing.
关键词 ：
High speed camera High speed camera Cell printing Cell printing Ejection frequency Ejection frequency Electrohydrodynamic Electrohydrodynamic
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| GB/T 7714 | Zhang Haiyi , Wang Can , Jia Ruiwen et al. Ejection of cell laden RPMI-1640 culture medium by Electrohydrodynamic method [J]. | BIOMEDICAL MICRODEVICES , 2019 , 21 (3) . |
| MLA | Zhang Haiyi et al. "Ejection of cell laden RPMI-1640 culture medium by Electrohydrodynamic method" . | BIOMEDICAL MICRODEVICES 21 . 3 (2019) . |
| APA | Zhang Haiyi , Wang Can , Jia Ruiwen , Wang Fei , Wang Yiwei , Wang Zhihai et al. Ejection of cell laden RPMI-1640 culture medium by Electrohydrodynamic method . | BIOMEDICAL MICRODEVICES , 2019 , 21 (3) . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Sample deposition based on micro-droplet ejection has broad application prospects in the field of biomedicine. Ejection of RPMI-1640 medium (without and with cells) is investigated experimentally using a home-build electrohydrodynamic (EHD) ejection system, consisting of a liquid supplier and a nozzle, a high voltage source, a droplet collector, and a high speed photography module. Electric voltage is applied between the nozzle and the droplet collector. The liquid surface is charged and the ejection takes place when electric force overcomes the surface tension. The ejection process is studied by using high speed photography and image processing. At low voltage, a uniform ejection state is established with ejection frequency typically less than 50Hertz. At sufficiently high voltage, another uniform ejection state is reached with ejection frequency as high as 1300Hz. Human peripheral blood mononuclear cells, after ejection, show survival rates higher than 79%, manifesting EHD ejection as a promising technique for cell printing.
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| GB/T 7714 | Zhang Haiyi , Wang Can , Wang Fei et al. Studies on Ejection of Cell Culture Medium by Electrohydrodynamic Method [C] . 2019 . |
| MLA | Zhang Haiyi et al. "Studies on Ejection of Cell Culture Medium by Electrohydrodynamic Method" . (2019) . |
| APA | Zhang Haiyi , Wang Can , Wang Fei , Wang Yiwei , Wang Zhihai , Chen Xi et al. Studies on Ejection of Cell Culture Medium by Electrohydrodynamic Method . (2019) . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Pneumatic valve-controlled micro-droplet generation is a printing technique that has potential applications in many fields, especially in the field of biomedical printing. The droplet generation is controlled by a solenoid valve being briefly turned on, so that high pressure gas enters the liquid reservoir, forming a gas pressure pulse P(t), forcing the liquid out through a tiny nozzle to form a micro-droplet. Under the typical working conditions, P(t) is not consistent. Since P(t) is highly correlated with the micro-droplet ejection state, the inconsistency of P(t) results in fluctuation of ejection state. For each injection, the P(t) is acquired by a high speed pressure sensor, and the ejection state is obtained by machine vision processing. A machine learning method based on BP neural network is used to establish a prediction model with P(t) as the input and the droplet ejection state as the output. Experiments show that a BP neural network with only a single hidden layer and two neurons can accurately predict the number of droplets with an accuracy higher than 99%. Another experiment shows that a more complex double hidden layer BP neural network can improve the prediction accuracy for the position of droplets after a certain time delay. In summary, through pressure pulse P(t), the predictive model established by the machine learning method can effectively predict the micro-droplet ejection state. This technique may be used for real time monitoring and control of the pneumatic valve-controlled micro-droplet generator.
关键词 ：
BP neural network BP neural network micro-droplet micro-droplet pneumatic pneumatic valve-controlled valve-controlled
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| GB/T 7714 | Wang Fei , Li Jiangeng , Wang Yiwei et al. Prediction of Ejection State for a Pneumatic Valve-controlled Micro-droplet Generator by a BP neural network [C] . 2018 : 977-982 . |
| MLA | Wang Fei et al. "Prediction of Ejection State for a Pneumatic Valve-controlled Micro-droplet Generator by a BP neural network" . (2018) : 977-982 . |
| APA | Wang Fei , Li Jiangeng , Wang Yiwei , Bao Weijie , Er Zhixuan , Wang Xiaoyi et al. Prediction of Ejection State for a Pneumatic Valve-controlled Micro-droplet Generator by a BP neural network . (2018) : 977-982 . |
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