Single cell detection in an electrical impedance based microfluidic biochip: A computational and experimental study
Lab tests for medical diagnostics are one of the most essential needs in modern healthcare. There is a broad spectrum of lab tests that includes common health monitors such as blood electrolytes/gases, cardiac markers, complete blood count, etc., and screening for infectious diseases such as TB, HIV, COVID-19 etc. The prevalent practice for lab tests involves a centralized diagnostic lab which requires sophisticated equipment and trained technicians. This poses major challenges including a long turnaround time spanning several hours to days, difficulty in accessibility and affordability for patients, especially in the developing countries. The recent advancement in biomedical technologies has offered revolutionary improvements in the typical lab testing landscape by offering portable, handheld & personalized tests (also called point of care). One of the ultimate point of care diagnostic device is the microfluidic-based Lab-on-a-Chip (LOC) technology with a broad range of applications in diagnostics. These platforms are noninvasive and have the distinct benefit of minimizing sample modification and allowing re-utilization.
In this thesis, a label-free impedimetric LOC device is developed and optimized. The biochip detects and count the target biomarker (cell or protein) using impedimetric based microfluidic systems. We explore the impact of device configuration during the cell counting and cell differentiation based on size and morphology in the microfluidic system. Finite element based simulation is used to model and optimize the configuration of multi-planar electrodes for multiple particle morphologies. A novel integrated multi-planar microelectrodes geometry is proposed that can detect any morphology of the biomarker flowing through a microchannel with a high signal to noise ratio.
The microelectrode designs are fabricated on a flexible substrate and are validated for MV4-11 cells and polystyrene beads. The proposed microelectrode design outperforms the traditional coplanar electrode layout in spike bipolar pulse amplitude, noise reduction, and signal-to-noise ratio. These promising findings lead to a new generation of microfluidic platforms based on novel microelectrode geometry to achieve real-time, cost-effective, and label-free single cell detection monitoring in healthcare. Microfluidics, despite its complexity, has innovative capabilities for the future. In future, more successful academic research will shed some light on how to unfold the potential of this interesting technology.
Amina Farooq, Nauman Z Butt, Umer Hassan, “Exceedingly Sensitive Restructured Electrodes Design for Pathogen Morphology Detection using Impedance Flow Cytometry”, 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 2020.
Farooq, Amina, Butt, N.Z. & Hassan, U, “Biochip with multi-planar electrodes geometry for differentiation of non-spherical bioparticles in a microchannel”, Sci Rep 11, 11880 (2021).
Farooq, Amina, Nauman Zafar Butt, and Umer Hassan. "Circular shaped microelectrodes for single cell electrical measurements for lab-on-a-chip applications." Biomedical Microdevices 23, no. 3 (2021): 1-12.
Amina Farooq, Nauman Butt, “Thin Flexible Lab-on-a-Film for Impedimetric Sensing in Biomedical Applications” submitted in IEEE Transactions on Biomedical Engineering. 2021.