Research status and application progress of microparticle preparation using microfluidic photocuring technology

(1) The shape of the above-mentioned microparticles is usually determined by the intersecting space defined by the microchannel (along the x-axis) and the UV light (along the z-axis). The shape control along the third axis (y-axis) needs to be further developed to further improve the molding capability of microfluidic photocuring. Shape control along the third axis is not limited to relying on microchannels and UV light, and it is also possible to explore other molding methods, such as lasers. In addition, the relative translation and rotation design between axial elements can also be considered to further enrich the types of microparticles.

(2) Since the curing of microparticles is based on photocrosslinking, the transparency of the precursor has an important influence on the formation of microparticles. The material and concentration of the functional additives in the precursor determine the transparency of the precursor, and the shape resolution of the microparticles is positively correlated with the transparency. As long as the additive meets one of the following requirements: high transparency, low concentration, and matching the refractive index of the surrounding solution, a high-transparency precursor can be obtained. However, many functional additives cannot meet the above requirements, such as magnetic and ceramic nanoparticle additives. In addition, the application performance of microparticles made with these additives is often positively correlated with the concentration of the additives, which makes microfluidic photocuring more difficult. Therefore, a variety of other photocurable precursors are expected to be further developed.

(3) The throughput of microfluidic photocuring is an important factor in linking scientific research with the practical application of microparticles. In order to improve productivity, the time required for each step of the "stop-polymerization-wash" cycle unit should be shortened as much as possible. In addition, parallel production is an effective strategy to further increase throughput.

(4) It is undeniable that most microfluidic photocuring manufacturing technologies are still at the laboratory stage, and there is a huge gap between experimental results and practical application requirements. For example, to date, the self-assembly of microparticles is still difficult to achieve without the help of manual operation, which hinders their further practical application in tissue engineering and other fields. At present, the 3D assembly structure of microparticles loaded with cells is still very simple, and it is still challenging to construct more sophisticated and complex 3D assembly structures.

In summary, the functional microparticles prepared by microfluidic photocuring technology have important application value and broad market prospects in many fields such as biomedical engineering, functional materials, and anti-counterfeiting. In order to further realize the benefits of microparticles to mankind, the joint efforts of many researchers and entrepreneurs are still needed.

Review editor: Liu Qing