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Optimization of electrochemical microfluidic biosensor design for point of care devices

University of British Columbia

Over the last decade, there has been an ever-increasing interest in microfluidic biosensors in the biomedical sector, especially for diagnosing infectious diseases. These are still one of the top ten causes of mortality around the world and for regions with limited resources where mortality rates are the highest, it is imperative to provide an on-site diagnosis. With early diagnosis, accurate treatments are possible, which can help contain and prevent disease outbreaks. However, there are still several challenges that need to be addressed to develop accurate and sensitive Point of Care (POC) detection devices. Improvements in sample processing, flow manipulation and signal amplification can support powerful emerging technologies for the development of fast, inexpensive, portable, easy-to-use and sensitive diagnostic devices. For the purpose of miniaturization, simple instrumentation, low production cost, and rapid response coupled with high sensitivity/selectivity, microfluidic DNA biosensors with an electrochemical transducer have shown great promise. This thesis focuses on experiments that aim to optimize three design aspects of an electrochemical microfluidic biosensor to improve its applicability: 1) flow cell geometry, 2) flow rate and 3) electrohydrodynamic mixing. Numerical simulations were carried out to model the fluid and particle behavior inside the detection cell. Understanding these flow characteristics led to the development of a new geometry providing uniform distribution of the sample flow across the detection area for increasing the biosensor’s efficiency. In addition, the identification of an optimal flow rate was required to analyze a higher sample volume. To achieve this, the binding efficiency of Streptavidin and Methylene Blue-Biotin was compared at five different flow rates with Square Wave Voltammetry. This resulted in finding an alternate flow rate that could increase the volume sample without sacrificing the selectivity/sensitivity of the detection technology. Lastly, a microdevice was fabricated to test the interaction between the electrostatic field and negatively charged polystyrene particles of different diameters. An electrohydrodynamic effect was observed in all samples, which can be utilized as an effective mixing technique. Overall, the results from the three design aspects could serve as a starting point to continue the optimization of electrochemical microfluidic biosensors and facilitate POC detection.

Text

2020-05-08

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/74373

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/