In the development of microfluidic systems, conventional 2D processing technologies are increasingly difficult to meet the requirement of integration of multifunctional components within a microchannel. Recently, two-photon polymerization (TPP) technology has emerged as a novel alternative to fabricate 3D microdevices functionalizing conventional microfluidic chips. Here, the development of TPP microfluidic technology comprising parallel fabrication, holographic patterning method and real-time lithography in a controlled flow is reported. And a series of functional microcomponents containing microfilters, microsorters, microtrap, tunable microlens are fabricated by above methods. The results indicate that the processing of microfluidic devices is simple, timesaving, low cost and programmable designability. The functional microchips are further used in blood cells sorting, biomedical sensing, microparticle purification and trapping with successful test results.
For microseparation devices, the quality of the microholes, e.g., smooth surfaces and edges, is of crucial importance for high-performance separating ability. Here, we used water-assisted femtosecond laser perforating technology to fabricate high-quality size-controllable (from several to tens of micrometers) micropore arrays on ultrathin aluminum foil surface, which have smooth edges without fragments and debris. The micropore arrays can effectively filtrate particles with diverse diameters. Compared to the micropores prepared in air under the same laser processing parameters, the water-assisted micropores have greatly improved the surface quality, and the particle separation ratio can be increased by ∼40 % . This method for preparing high-quality micropore arrays can also be applied to other sheet materials, such as titanium, silicon, and even plastic, and so on, which can be widely used in the fields of microfluidic devices for microseparation.
Recently, annular beams have been developed to rapidly fabricate microscope tubular structures via two-photon polymerization, but the distribution of the light field is limited to a ring pattern. Here a Fresnel lens is designed and applied to modulate the light field into a uniform quadrangle or hexagon shape with controllable diameters. By applying a spatial light modulator to load the phase information of the Fresnel lens, quadrangle and hexagon structures are achieved through single exposure of a femtosecond laser. A 3×6 array of structures is made within 9 s. Comparing with the conventional holographic processing, this method shows higher uniformity, high efficiency, better flexibility, and easy operation. The approach exhibited a promising prospect in rapidly fabricating structures such as tissue engineering scaffolds and variously shaped tubular arrays.
The surface induced flow in micro groove has attracted much attention because it can be used as a passive power source
in microfluidic devices. In recent years, some researchers have used the surface induced force to deliver liquids in micro
groove. The flow speed should be controlled accurately in order to displace liquids with desirable volumes. In this paper,
we investigated the feasibility to control the flow speed by constructing microstructure on surface groove using
femtosecond laser. Firstly, we used femtosecond laser to fabricate different microstructures on alumina surfaces with
different laser scanning speed. It was found that the flow speed in groove increased when the femtosecond laser scanning
speed decreased. And the liquid spread distance was linear to the square of spread time. Then we investigated the
dynamics of the liquid flow which was influenced by the surface chemical composition property. Some metal materials
with different surface energies were sputtered on the irradiated surface. The coated metal film can also change the liquid
spread speed in groove. This work provides a method to obtain the expected controllable spread speed by constructing
the microstructure using femtosecond laser.
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