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Title:Microfluidic sensor for white blood cell counting and flow metering
Author(s):Hassan, Umer
Advisor(s):Bashir, Rashid
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Cell counting
Electrical flow metering
Complete blood cell count
White blood cell counting
Abstract:Cell counting finds many applications in diagnostics of many diseases. One of the most common tests recommended by the physicians is Complete Blood Cell Count (CBC). For example, there is a decrease in the platelet count in case of Dengue fever. Red blood cells decrease in the case of anemia. CD4 T cells decrease in the case of HIV/AIDS. Cell counting in general, and ability to count the specific cells, would greatly help in clinical diagnostics. Currently, flow cytometers are used for this purpose, but they have not been able to penetrate in the resource-limited settings around the world because of being expensive and because they require trained technicians to operate. Over many years, people have developed microfluidic devices for cell counting, which could provide a portable and economical solution to the problem of cell counting at point-of-care. In this report, we present a technique for counting the white blood cells and differentiating some of its sub-types within a microfluidic device. Starting with the whole blood, the red blood cells are lysed by saponin and formic acid. Quenching solution composed of phosphate buffer saline is infused in the device to halt the lysing process and maintain the pH of the solution. The remaining white blood cells are then passed across micro-fabricated electrodes within a microfluidic channel. The impedance is measured at 303 kHz and 1.7 MHz signals. The height of the pulse is proportional to the size of the cell. By selecting the appropriate threshold, the number of the cells can be calculated, and white blood cell sub-types can be differentiated based on their size. Lysed blood flow metering is also possible using the same setup. The width of the pulse for each passage of the cell through the electrode is proportional to the speed of the cell. By investigating the pulse width, the flow rate can be monitored. Similarly, with increasing flow rates, the baseline amplitude measured in between the electrodes is also proportional to the flow rate. This device has the potential for use in counting specific types of white blood cells. In particular, we are currently characterizing the device for counting of CD4+ and CD8+ T lymphocytes, which are the primary diagnostics biomarkers for HIV/AIDS.
Issue Date:2013-05-24
Rights Information:Copyright 2013 Umer Hassan
Date Available in IDEALS:2013-05-24
Date Deposited:2013-05

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