A Passive Pumping Microfluidic Coulter Counter

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Title: A Passive Pumping Microfluidic Coulter Counter
Author: McPherson, Amy
Advisors: Dr. David Lalush, Committee Member
Dr. Glenn Walker, Committee Chair
Dr. Greg McCarty, Committee Member
Abstract: As a result of the growing costs of healthcare technology, there is an increasing need for medical diagnostic tools that provide accurate information in a portable, low-cost platform. A microfluidic device using on-chip passive pumping was characterized for use as a particle counter. A detection circuit interfaced with electrodes in the microfluidic chip to provide an excitation signal and to detect electrical activity. Flow occurred due to a Young-Laplace pressure gradient between a 1.2 mm diameter inlet and a 4 mm diameter reservoir when 0.5 μL fluid droplets were applied to the inlet using a micropipette. Polystyrene particles were enumerated using the resistive pulse technique, in which particles can be detected based on the difference in particle conductivity from that of the surrounding medium. Particles counted using the passive flow method demonstrated mean particle counts that were within 13% of those detected using a syringe pump, while all pumping methods displayed particle counts that were within 16% of the count obtained using a hemacytometer. Three different sample loading patterns were compared; the methods varied only in the order of sample and wash fluid administration. Zero, one, or two wash droplets were loaded after the first of two sample droplets. No statistical difference was detected in the mean particle counts for all loading patterns using the passive method (p > 0.05). This passive pumping method is easily implemented using only a micropipette, thus reducing the cost and complexity of particle enumeration, and the method can be implemented in a point-of-care (POC) device for a highly portable, cost-effective particle counter. These methods obtained particle counts that were also consistent with syringe pumping (p > 0.05).
Date: 2009-11-20
Degree: MS
Discipline: Biomedical Engineering
URI: http://www.lib.ncsu.edu/resolver/1840.16/1504

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