Authors: Renjie Ning, Blake Acree, Mengren Wu, and Yuan Gao
Researchers led by Renjie Ning from the University of Memphis have developed an innovative microfluidic approach for generating monodispersed microbubbles, which are crucial for cavitation studies. Their work, published in the journal Micromachines, presents a significant advancement in the field of microbubble production.
Microbubbles are tiny gas-filled spheres that play a vital role in various applications, including medical imaging and drug delivery. When exposed to ultrasound, these bubbles undergo cycles of expansion, contraction, and collapse, generating shockwaves and altering local shear stresses. This behavior makes them ideal cavitation nuclei for studying complex fluid dynamics phenomena. Microfluidic platforms, which allow precise control over microscale fluid dynamics, also offer several advantages for this application. Chief among these are excellent monodispersity and high throughput production, both possible due to continuous controlled fluid flow.
Figure 1. Schematic illustration of the experimental setup and an optical image of the microfluidic microbubble generator.
The team's microfluidic device employed a T-junction structure to produce highly uniform microbubbles as small as 20 micrometers. By manipulating parameters such as gas pressure, pressure ratio, and channel geometry, they achieved fine control over bubble size and uniformity. The polydispersity index (PDI) could go below 0.053 with optimal channel design, demonstrating the precision of this method.
Figure 2. (A) Minimum-sized bubbles generated in a T-junction with D = 100 µm; W = 200 µm. (i.) Microbubble generation. (ii.) Microbubbles collected in the chamber. (iii.) Microbubble size distribution and polydispersity. (B) Minimum-sized bubbles generated in a T-junction with D = 50 µm; W = 200 µm. (C) Minimum-sized bubbles generated in a T-junction with D = 50 µm; W = 100 µm.
Accurate and stable fluid handling are crucial for controlled microfluidic experiments such as this. The iFlow pressure controller from PreciGenome was chosen by the authors for its minimal fluctuation during air pressurization.
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