Document Type


Date of Award

Fall 1-31-2011

Degree Name

Master of Science in Biomedical Engineering - (M.S.)


Biomedical Engineering

First Advisor

Max Roman

Second Advisor

William C. Van Buskirk

Third Advisor

Richard A. Foulds

Fourth Advisor

Hans Raj Chaudhry


A wide interest in employing micron-scale, integrated biochemical analysis systems for economical and rapid diagnosis has been the principal motivation behind this project. Low operating costs, portability and fast diagnosis times make centrifugal microfluidic devices an attractive option in patient-side diagnostics. Some essential tasks to be performed in microfluidic devices are sample-reagent transport, mixing, separation and detection. All these tasks require precise control of the RPM and spinning time. Centrifugal micro-fluidic platforms have been successfully implemented for detection of hepatitis A, tetanus, as well as for measurement of haemoglobin and hematocrit, for DNA analysis, and for assessment of cardiac disease etc. by assaying biological fluids like blood, saliva, and urine.

This thesis presents the construction, including the micro-machining and testing of a multi-channel centrifugal microfluidic device for point-of-care (POC) diagnostics. A low cost device capable of delivering controlled revolutions per minute was made by modifying a CD-ROM drive and a polymer disk was used to handle the fluids. A network of microfluidic channels and reservoirs was fabricated on the CD by using a rapid prototyping method. The reservoirs hold the biofluid sample, meter the volume of fluid accurately and also serve as a component of capillary burst valves to gate the flow of fluid. Micromachining techniques like photolithography, wet-etching have been discussed for mass production of the prototype used for this research.

Theoretical analysis of the burst frequency for passive capillary valves is reported and compared with practical results. The goal of this thesis was to develop a low cost device and demonstrate its use in the separation, and metering of plasma from blood using centrifugal microfluidics. One challenge when using blood for diagnosis is to separate the blood plasma from the rest of the blood cells. Concepts of blood centrifugation and particle displacement on a spinning disk have been employed to calculate the required RPM. Experiments were carried out on various geometries in order to achieve the maximum level of separation. The results of these experiments have been reported. It has been established that centrifugal microfluidics can be used to accurately control the flow of fluids in microchannels and this can be used for reliable low cost point-of-care diagnostics.



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