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theses

We present a portable system for personalized blood cell counting consisting of a microfluidic impedance cytometer with portable analog readout feeding into an analog-to-digital converter (ADC). The novel design of the analog readout, which consists of a lock-in-amplifier followed by a high-pass filter stage for subtraction of drift and DC offset, and a post-subtraction high gain stage, enables detection of particles and cells as small as 1 m in diameter, despite using a low-end 8 bit ADC. Applications such as personalized health monitoring require robust device operation and resilience to clogging, thus it is desirable to avoid using channels comparable in size to the particles being detected, thus requiring high levels of sensitivity. Despite using low-end off-the-shelf hardware, our sensing platform was capable of detecting changes in impedance as small as 0.032%, allowing detection of 3 m diameter particles in 300 m wide channel. The consecutive upward and downward signature of recorded peaks further helps to differentiate the signal from the noise floor. The performance of our system is comparable to that of a high-end bench-top impedance spectrometer under experimental condition. The novel analog design allowed for an instrument with a footprint of less than 80 cm2. The aim of this work was to demonstrate the potential of using microfluidic impedance spectroscopy for low-cost health monitoring. We demonstrated the utility of the platform technology towards cell counting, however our platform is broadly applicable to assaying wide panels of biomarkers including proteins, nucleic acids, and various cell types.

ETD_7561

M.S.

Includes bibliographical references

by Niloy Talukder

doi:10.7282/T30R9RR2

ETD graduate

The author owns the copyright to this work.