Several studies have already demonstrated that it is possible to perform blood flow studies in microfluidic systems fabricated by using low-cost techniques. However, most of these techniques do not produce microchannels smaller than 100 microns and as a result they have several limitations related to blood cell separation. Recently, manufacturers have been able to produce milling tools smaller than 100 microns, which consequently have promoted the ability of micromilling machines to fabricate microfluidic devices able to perform separation of red blood cells (RBCs) from plasma. In this work, we show the ability of a micromilling machine to manufacture microchannels with dimensions down to 30 microns. Additionally, we show for the first time the ability of the proposed microfluidic device to enhance the cell-free layer close to the walls, leading to perform partial separation of RBCs from plasma.
The most common and used technique to produce microfluidic devices for biomedical applications is the soft-lithography. However, this is a high cost and time-consuming technique. Recently, manufacturers were able to produce milling tools smaller than 100 m and consequently have promoted the ability of the micromilling machines to fabricate microfluidic devices capable of performing cell separation. In this work, we show the ability of a micromilling machine to manufacture microchannels down to 30 m and also the ability of a microfluidic device to perform partial separation of red blood cells from plasma. Flow visualization and measurements were performed by using a high-speed video microscopy system. Advantages and limitations of the micromilling fabrication process are also presented.
The diagnosis of several diseases can be performed by analyzing the blood plasma of a patient. Despite extensive research work, there is still a need to improve current low-cost fabrication techniques and devices for the separation of plasma from blood cells. Microfluidic biomedical devices have great potential for that process. Hence, a microfluidic device made by micromilling and sealed with an oxygen plasma technique was tested by means of two different blood analogue fluids. The device has four microchannels with similar geometries but different channel depths. A high-speed video microscopy system was used for the visualization and acquisition of the flow of the analogue fluids throughout the microchannels of the device. Then, the separation of particles and plasma was evaluated with the ImageJ software by measuring and comparing the grey values at the entrance and the exit of the channel. The device showed a significant reduction of the amount of cells between the entrance and the exit of the microchannels. The depth of the channels and the size of the particles were not found to exert any major influence on the separation process. However, it was found that the flow rate affected the separation results, as the best results were obtained for a flow rate of 100 μL/min. Though these results are promising, further analyses and optimizations of microfluidic devices, as well as comparisons between devices sealed using different methods such as the solvent bonding technique, will be conducted in future works.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.