PDMS top and bottom 3D printing of assembled microfluidic chips is often used in microfluidic technology to handle manipulation and control of sub-millimeter fluid flow in microchannels . Researchers have developed a number of microfluidic devices to aid in cell analysis, benefiting the medical field. According to the Mammons Consulting, Annal Arumugam Arthanari Arumugam from the University of Saskatchewan (University of Saskatchewan) published an article entitled "Based on the principle of sliding to help sort potential cells of different sizes The applied thesis of Microfluidic Devices, focusing on a new microfluidic device design concept called the sliding principle. In the paper, Arumugam said that although most microfluidic devices can capture, separate, localize and sort individual cells, most can only be used for cells of the same size. Tunable microfluidic devices can be used to capture and sort individual cells ranging in size from 20 to 30 μm, but many applications require sizes ranging from 2 μm to 100 μm, even larger.
Experimental device for testing channel spacing states that "this article first analyzes the different working principles used to capture and sort single cell devices, trying to find a solution to the problem. As a result, this paper presents A new principle for sorting single cells ranging in size from 2 μm to 100 μm, a principle known as the 'sliding principle'. To validate the validity of this principle, researchers have designed this principle based on this principle. A device comprising a micro-trap or micro-pore, which is designed and manufactured using soft lithography, in which the mold is fabricated using 3D printing technology. The researcher uses a microscope (resolution: 1-3 μm) and moves The platform (resolution: 1 μm) was unfolded and it was proved that the device can adapt to the size of the micropore trap.The range is from 0-1000 μm and can cover the size range of the desired micropores (for example: 2-100 μm). Based on current literature on mechanical methods for capturing and sorting single cells of different sizes with one device, devices constructed based on the sliding principle are expected to be suitable for capturing and sorting single cells of different sizes. The overall functional requirements of the device (function requirement, FR) are capable of capturing cells of different sizes, from 2 μm to 100 μm with a resolution of 2-5 μm. Sub-function requirements include: * Formation Slide the pair to change the size of the trap with the slide* Ability to run a slide trap* Pumping cell fluid through the trap
Adjustable trap sliding principle (a) The trap is a square with four sides slidable; (b) The microfluidic device that slides one side to change the size of the trap to contact the cells must be made of biocompatible material Made, the maximum stress in the cell should be less than 4.5 Pa and the sliding adjustment range is less than 1000 μm. Arumugam considered two design choices for his sliding trap, but the first one was unsuccessful because the contact surfaces of the two blocks were not smooth enough There is no smooth sliding between the block and the block, and it may cause a leak. So he turned to focus on the second design choice.
Arumugam explains, "This design is divided into two layers (top And the bottom layer), each layer has several micropores (however, this paper only designed a micropore, but without loss of generality),The micropore shape is square. Specifically, at the top layer, the square is a convex surface with a protruding portion, and the square of the bottom layer is a concave surface. When the two layers are assembled together (the top layer is above the bottom layer), they form a system..."
Driver rails, brackets, top-level blocks and bottom blocks of the top-level block, by PDMS The embedded layer made of methyl siloxane constitutes the driving device; a single axial platform with a resolution of about 3 um is made of 835 rigid opaque white material to help drive the top layer. Arumugam uses Polyjet 3D printing technology for The PDMS part is used to make the mold. When testing the design, the device is measured to see if it meets the “Geometry and Topology Device Design Specification”.The researchers also measured the sliding operation to "check the change in microwells." The measured values of the PDMS layer are satisfactory, indicating that the sliding principle concept is indeed effective, and the side of the PDMS layer is slightly eroded, making the channel spacing less precise; the cause of the damage is that the viscous PDMS is not peeled off from the mold during the curing process. .
3D printing dies and sliding assemblies for the PDMS layer, added by Arumugam, the university's engineering studio. "In the first few experimental attempts, PDMS did not cure well, PDMS layer (injected parts) ) adhered to the mold and damaged during the peeling process. To solve this problem, we pre-bake the 3D printing mold in the oven at 85 ° C for 4 hours, and then cure the PDMS layer.The problem has not completely disappeared. This problem can lead to inaccuracies in the size of the molded part (with an error of about 2 um), which also causes surface damage. Part of the resolution problem can be attributed to a channel size of 1mm. The channel size affects the focus of the microscope, which in turn affects the number of pixels covered by the view, ultimately affecting pixel resolution, especially as the pixel length becomes 8.547 um. Assuming a maximum channel size of 100 μm, the measurement resolution will be 0.855 um. The author also cited some work to help advance microfluidic device technology, such as optimizing the fabrication of PDMS channels and further modifying his design.