Separation Microfluidic Device Fabricated by Micromilling Techniques

Abstract

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.

Low-cost microfluidics: Towards affordable environmental monitoring and assessment

“…Although the selection of resins for printing transparent parts and molds is limited, with the rapid advances in this technology, 3D printing resins that promote better resolution, surface finishing and transparency would further enhance the capabilities of microfluidic devices; in fact, there are resins currently being developed with the specific purpose of fabricating microfluidic devices (e.g., Figure 4E) (He et al, 2016;Nielsen et al, 2020). For further discussion on 3D printing technologies applied to microfluidic devices manufacturing, the readers are encouraged to review the following references: (Chen et al, 2016;He et al, 2016;Enders et al, 2019;de Almeida Monteiro Melo Ferraz et al, 2020;Gonzalez et al, 2020;Nielsen et al, 2020;Mehta and Rath, 2021).…”

“…Micromilling only removes the materials from external surfaces, therefore bonding with other substrates is inevitable to create enclosed microchannels. The bonding could be done mechanically (i.e., using screws), thermally (i.e., bonding two PMMA plates when heated up), or using surface treatments and adhesives such as the tapes (Kosoff et al, 2018;Owens and Hart, 2018;Madureira et al, 2019;Gonçalves et al, 2021).…”