Lab-on-Chip Microdevices for Capturing, Imaging and Counting White Blood Cells.

Abstract

White blood cells (WBCs) and their subtypes are important constituents of the human immune system as their concentration, quantified by a WBC count test, indicates the state of body’s immune response against infections. These cell count tests are important prognostic and diagnostic indicators for a number of human immunological diseases, most prominent of them being AIDS. Flow cytometry (FC) is the gold standard for counting WBCs. Although high throughput and accurate, FC based instruments are bulky, expensive and require skillful and trained personnel for their operation and maintenance. This necessitates the development of inexpensive, portable point-of-care (POC) systems for capturing and enumerating WBCs and their subtypes.

We envision a portable, point-of-care WBC counting system which can capture thousands of WBCs and simultaneously image and count them. Towards this end, we have developed: - A microfluidic biochip for trapping and counting WBCs. The biochip has a novel 3D cell trapping architecture and enables simultaneous capture and counting of thousands of WBCs. A WBC trapping efficiency of ~90% is achieved using the biochip. - Microlens arrays with a large field of view (FOV) imaging capability that have an optical performance (numerical aperture, resolution) equivalent to a conventional microscope objective.

We envision that the cell trapping biochip and the microlens arrays proposed in this thesis can be integrated to perform simultaneous on-chip capture and imaging/counting of WBCs. The integrated microsystem can also be used as a generic platform for sorting and enumeration of different kinds of cells for disease diagnosis and research applications.