image: Schematical illustrations of the fabrication process of microhelices in microfluidics.
Credit: Liang-Yin Chu, School of Chemical Engineering, Sichuan University, Sichuan, China
The microhelices, due to their unique spiral spatial structure, can achieve many functions similar to micromotors. Therefore, developing microhelices with diverse structures and functions has become a research hotspot in the field of microfluidics. However, the CaAlg gel formed in situ by the traditional NaAlg - CaCl2 system is prone to causing microchannel blockage, which seriously affects the preparation accuracy and efficiency. Moreover, the prepared microhelices often cannot balance both biocompatibility and high mechanical properties. In this regard, in a recent study of "Green Chemical Engineering", the research team led by Prof Liang-Yin Chu from Sichuan University reported a simple method for the preparation of microhelices with diverse structures and functions.
"Microfluidic technology can precisely control microfluids. Through the unique two-stage coaxial microfluidic device and the core-sheath microhelical template, microhelices can be easily constructed, and then PEGDA microhelices can be prepared by UV online initiation of the core flow. Benefiting to the double-layer microfluidic structure, high substrate content microhelices can be obtained, thus exhibiting excellent mechanical properties." shares Prof Chu.
Usually, the inner phase fluid has the role of initiating coiling and generating the master mold, so it cannot be effectively regulated separately. Therefore, introducing the microhelical template to overcome this problem. By adjusting the operating conditions (such as fluid properties, device dimensions, and multiphase flowrates), the structure of the microhelices (such as pitch, diameter, amplitude, and length) can be efficiently regulated, and a quantitative relationship formula has been established, providing important guidance for customizing microhelices with specific structures.
Prof Chu added: "PEGDA@Fe3O4 microhelices, due to their excellent helical structure and mechanical properties, have shown excellent motion performance in microchannel simulation experiments. Their motion speed can reach 6 mm/s, and they can also efficiently move in human blood (5 mPa·s), even transporting 34 times their own weight of microspheres."
The researchers pointed out that this simple method can be coupled with other substrate types and functional components to expand the functions and applications of microhelices, especially in areas such as intelligent wearables and thrombus clearance, for focused application.
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Journal
Green Chemical Engineering
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Controllable fabrication of biocompatible microhelices based on the liquid rope coiling effect due to the phase viscosity difference
COI Statement
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.