scholarly journals Droplet Generation in a Flow-Focusing Microfluidic Device with External Mechanical Vibration

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 743
Author(s):  
Zhaoqin Yin ◽  
Zemin Huang ◽  
Xiaohui Lin ◽  
Xiaoyan Gao ◽  
Fubing Bao
Keyword(s):  
Microfluidic Device ◽  
Vibration Frequency ◽  
Linear Correlation ◽  
Vibration Amplitude ◽  
Mechanical Vibration ◽  
Droplet Generation ◽  
Flow Focusing ◽  
Generation Frequency ◽  
External Vibration ◽  
Shrinkage Process

The demand for highly controllable droplet generation methods is very urgent in the medical, materials, and food industries. The droplet generation in a flow-focusing microfluidic device with external mechanical vibration, as a controllable droplet generation method, is experimentally studied. The effects of vibration frequency and acceleration amplitude on the droplet generation are characterized. The linear correlation between the droplet generation frequency and the external vibration frequency and the critical vibration amplitude corresponding to the imposing vibration frequency are observed. The droplet generation frequency with external mechanical vibration is affected by the natural generation frequency, vibration frequency, and vibration amplitude. The droplet generation frequency in a certain microfluidic device with external vibration is able to vary from the natural generation frequency to the imposed vibration frequency at different vibration conditions. The evolution of dispersed phase thread with vibration is remarkably different with the process without vibration. Distinct stages of expansion, shrinkage, and collapse are observed in the droplet formation with vibration, and the occurrence number of expansion–shrinkage process is relevant with the linear correlation coefficient.

scholarly journals Negative Pressure Provides Simple and Stable Droplet Generation in a Flow-Focusing Microfluidic Device

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 662
Author(s):  
Nikita A. Filatov ◽  
Anatoly A. Evstrapov ◽  
Anton S. Bukatin
Keyword(s):  
Microfluidic Device ◽  
Negative Pressure ◽  
Low Cost ◽  
Control Valve ◽  
Droplet Microfluidics ◽  
Droplet Generation ◽  
Electric Signal ◽  
Absolute Pressure ◽  
Flow Focusing ◽  
Wide Range

Droplet microfluidics is an extremely useful and powerful tool for industrial, environmental, and biotechnological applications, due to advantages such as the small volume of reagents required, ultrahigh-throughput, precise control, and independent manipulations of each droplet. For the generation of monodisperse water-in-oil droplets, usually T-junction and flow-focusing microfluidic devices connected to syringe pumps or pressure controllers are used. Here, we investigated droplet-generation regimes in a flow-focusing microfluidic device induced by the negative pressure in the outlet reservoir, generated by a low-cost mini diaphragm vacuum pump. During the study, we compared two ways of adjusting the negative pressure using a compact electro-pneumatic regulator and a manual airflow control valve. The results showed that both types of regulators are suitable for the stable generation of monodisperse droplets for at least 4 h, with variations in diameter less than 1 µm. Droplet diameters at high levels of negative pressure were mainly determined by the hydrodynamic resistances of the inlet microchannels, although the absolute pressure value defined the generation frequency; however, the electro-pneumatic regulator is preferable and convenient for the accurate control of the pressure by an external electric signal, providing more stable pressure, and a wide range of droplet diameters and generation frequencies. The method of droplet generation suggested here is a simple, stable, reliable, and portable way of high-throughput production of relatively large volumes of monodisperse emulsions for biomedical applications.

Alternating droplet generation and controlled dynamic droplet fusion in microfluidic device for CdS nanoparticle synthesis

Lab on a Chip ◽  
2006 ◽  
Vol 6 (2) ◽  
pp. 174 ◽  
Author(s):  
Lung-Hsin Hung ◽  
Kyung M. Choi ◽  
Wei-Yu Tseng ◽  
Yung-Chieh Tan ◽  
Kenneth J. Shea ◽  
...  
Keyword(s):  
Microfluidic Device ◽  
Nanoparticle Synthesis ◽  
Droplet Generation ◽  
Cds Nanoparticle

scholarly journals The Combined Effects of Co-Culture and Substrate Mechanics on 3D Tumor Spheroid Formation within Microgels Prepared via Flow-Focusing Microfluidic Fabrication

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 229 ◽  
Author(s):  
Dongjin Lee ◽  
Chaenyung Cha
Keyword(s):  
Mechanical Properties ◽  
Cell Culture ◽  
Microfluidic Device ◽  
3D Cell Culture ◽  
Breast Adenocarcinoma ◽  
Adherent Cell ◽  
Flow Focusing ◽  
Spheroid Formation ◽  
3D Scaffold ◽  
Tumor Spheroids

Tumor spheroids are considered a valuable three dimensional (3D) tissue model to study various aspects of tumor physiology for biomedical applications such as tissue engineering and drug screening as well as basic scientific endeavors, as several cell types can efficiently form spheroids by themselves in both suspension and adherent cell cultures. However, it is more desirable to utilize a 3D scaffold with tunable properties to create more physiologically relevant tumor spheroids as well as optimize their formation. In this study, bioactive spherical microgels supporting 3D cell culture are fabricated by a flow-focusing microfluidic device. Uniform-sized aqueous droplets of gel precursor solution dispersed with cells generated by the microfluidic device are photocrosslinked to fabricate cell-laden microgels. Their mechanical properties are controlled by the concentration of gel-forming polymer. Using breast adenocarcinoma cells, MCF-7, the effect of mechanical properties of microgels on their proliferation and the eventual spheroid formation was explored. Furthermore, the tumor cells are co-cultured with macrophages of fibroblasts, which are known to play a prominent role in tumor physiology, within the microgels to explore their role in spheroid formation. Taken together, the results from this study provide the design strategy for creating tumor spheroids utilizing mechanically-tunable microgels as 3D cell culture platform.

Real Time Acoustic Imaging by Holographic Interferometry

1980 ◽  
Vol 2 (4) ◽  
pp. 313-323 ◽  
Author(s):  
Amin Hanafy ◽  
Mauro Zambuto
Keyword(s):  
Real Time ◽  
Holographic Interferometry ◽  
Vibration Amplitude ◽  
Imaging System ◽  
Mechanical Vibration ◽  
Visual Image ◽  
Acoustic Imaging ◽  
Acoustic Image ◽  
Vibration Pattern ◽  
Amplitude Amplification

A two-step real time acoustic imaging system is presented. The system incorporates a novel acoustic image coupler which transfers an acoustical interference pattern from a water-bounded to an air-bounded surface with vibration amplitude amplification. An original technique termed step-biased real time holographic interferometry is used to convert the amplified mechanical vibration pattern, which carries all information about the insonified object, into a visual image with improved sensitivity.

Encapsulation of single cells on a microfluidic device integrating droplet generation with fluorescence-activated droplet sorting

2013 ◽  
Vol 15 (3) ◽  
pp. 553-560 ◽  
Author(s):  
Liang Wu ◽  
Pu Chen ◽  
Yingsong Dong ◽  
Xiaojun Feng ◽  
Bi-Feng Liu
Keyword(s):  
Microfluidic Device ◽  
Single Cells ◽  
Droplet Generation ◽  
Droplet Sorting
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