Flow Cytometry on a Chip - Point-of-Care Diagnostics on a Chip - page 62

Our method is intended to overfill a large excitation area to increase the total flux
of fluorescence light that originates from a particle and to be relatively alignment
insensitive. The large excitation area could be illuminated by an LED rather than a
laser, a feature that cannot be achieved in classical flow cytometer setups. The mask
pattern enables a high spatial resolution - comparable to classical flow cytometers -
and it is aligned relative to the flow channel during the production of the fluidic chip.
The detection technique has been extensively evaluated with measurements
of absolute CD4 and percentage CD4 counts in human blood. More recent

experiments demonstrate that the platform can address a large variety of diagnostic
needs including multiplexed bead-based assays and identification and enumeration
of pathogens (e.g., Giardia , Cryptosporidium, and E. Coli ) in fluids.
We foresee that the future of most POC testing devices lies in the integration of
sample collection and preparation into a disposable cartridge. We have described an
optical detection technique that is compatible to this approach because it provides
the necessary alignment tolerance, sensitivity, and price reduction.

C

Acknowledgment The work on the spatial modulation technique and its application in flow
cytometry was partially supported by grants from the National Institute of Health (5R21EB011662-
02) and the US Army Research Office (W911NF-10-1-0479).

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