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2 Computer Assisted Methods in Engineering and Science

2 2023

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Microfluidic design for continuous separation of blood particles and plasma using dielectrophoretic force principle

Pakhira Writtick, Kumar Rajagopal, Panwala Fenil Chetankuma, Ibrahimi Khalid Mohd

Computer Assisted Methods in Engineering and Science

2023

Vol. 30, no. 3

323--345

Nowadays, various microfluidic platforms are developed with a focus on point-of-care diagnostics in the biomedical field. Segregation of blood cells and plasma remains an essential part of medical diagnosis in which isolation of platelets (PLTs), red blood cells (RBCs), and white blood cells (WBCs) is a requirement for analysis of diseases associated with thrombocytopenia, anemia, and leukopenia. However, a separated plasma contains proteins, nucleic acids, and viruses, for which a microfluidic device is introduced for continuous separation of PLTs, RBCs, and WBCs with a diameter range of 1.8–2 m, 5–6 m, and 9.4–14 m, respectively, and plasma using the negative dielectrophoresis (DEP) force principle. In this study, design of the device is explored utilizing COMSOL Multiphysics 5.4 tool. This design consists of triangular micro-tip electrodes at the top, which are effective in generating a nonuniform electrical field with a significantly small AC voltage. Furthermore, the blood cells are subjected to the negative DEP force resulting in deflection toward their respective outlets, due to which blood cell separation purity and efficiency from the sample, i.e., of PLTs, RBCs, and WBCs, improve and are obtained at a blood sample flow velocity of 700 m/s and buffer solution flow velocity of 1200 m/s with 12 Vpp electrode voltage, after experimenting and testing at multiple flow velocities. Additionally, a curved microchannel is introduced, producing better plasma flow velocity than a flat microchannel at the side outlets (top and bottom). The cell-free diluted plasma is collected at side outlets (top and bottom) with high purity and improved separation efficiency.

Enhanced design and analysis of the microcantilever-based bio-sensor to detect carcinoembryonic antigen tumor biomarkers

Ibrahimi Khalid Mohd, Kumar Rajagopal, Pakhira Writtick

Computer Assisted Methods in Engineering and Science

2023

Vol. 30, no. 3

347--367

Frequently, early detection of a malignant condition prevents most premature deaths. In this paper, three new designs are proposed for the microcantilever-based biosensor to detect carcinoembryonic antigen (CEA) tumor biomarkers. CEA is used for several types of human cancers, e.g., lung cancer, pancreatic cancer, breast cancer, ovarian cancer, and gastric cancer, particularly colorectal cancer. The proposed models are designed and the finite element method (FEM) analysis of these biosensors is performed using a COMSOL 5.4 Multiphysics (commercial package) software. Various analyses and comparisons are carried out by utilizing the designs in terms of displacement as well as piezo-resistive output due to an increase in mass of CEA adsorbed onto the surface of the cantilever beam, which is stimulated by applying a pressure range of 0 to 0.2 Pa on to the surface of a cantilever beam. A simulation is performed with the proposed designs by experimenting with different materials for better deflection results. Regarding the results obtained, Design 3, made with Kynar710, gives the highest total deflection of 0.7328 m. However, a piezo-resistive readout technique is utilized to get the output in mV, and for that, p-silicon (single-crystal, lightly doped) material is used, respectively. Next, 5V is applied to the terminals of the piezo-resistive circuit. Based on the input applied pressure and output mV, the Design 3 made with Kynar710 gives a better sensitivity of 0.13089 [mV/V/Pa] compared to other designs made with other materials.