Past Research |
Digital Flow Cytometric Classification of Biological Cells
Students: Bo Xia, Nick A. Zilmer, Sundararajan Sankaranarayanan, Shiva Murthi,
Mahesh Godavarti
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Flow cytometry makes use of reflected laser light to analyze and classify
biological cells.The laser light strikes the cell, is reflected, and sensed by a photomultiplier
tube, resulting in a 1-D signature profile of the cell. We developed a digital
signal processing system that augments the commercial, analog flow cytometer.
The 1-D analog signal is digitized, and waveform features are digitallycomputed.
A prototype of a second-generation digital data acquisition
system (DDAPS-2), a mixed-signal design operating at 40 MHz, was built to
interface to a commercial flow cytometer. The DDAPS-2 intercepts the analog
signal from the photomultiplier tube and preamp, performs analog-to-digital
conversion, extracts various features and then feeds these extracted
features into one of the several pattern classification algorithms.
The novelty of the DDAPS-2 is the use of dual-buffering FIFO memories to acquire digital samples of the pulse
voltage signal.
Through experimental results using a variety of cell types, we
demonstrated that the digital system provides improved performance compared to
the analog system since a much richer set of features can be used to
discriminate cell populations. Experimental results also demonstrated the improvement in the
pulse capture performance of DDAPS-2 over DDAPS-1, which used a single-buffering FIFO memory.
This work was a collaborative effort with Prof. David W. Galbraith in the Dept. of Plant Sciences.
Publications:
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Shiva Murthi, Sundararajan Sankaranarayanan, Bo Xia,
Georgina M. Lambert, Jeffrey J. Rodriguez, and
David W. Galbraith, "Performance Analysis of a Dual-Buffer
Architecture for Digital Flow Cytometry," Cytometry,
Part A, vol. 66A, no. 2, Aug. 2005, pp. 109-118. [ PDF ]
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Shiva Murthi, Sundararajan Sankaranarayanan, Bo Xia, Jeffrey J.
Rodriguez, and David W. Galbraith, "An Improved Data
Acquisition System for Digital Flow Cytometry," in Proc. 2002 IEEE
Intl. Symp. on Circuits and Systems, Scottsdale, AZ, May 26-29,
2002, vol. 1, pp. 669-672. [ PDF ]
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Jeffrey J. Rodriguez, David W. Galbraith, Bo Xia, Kusnadi,
Timothy A. Yopp, Shiva Murthi, and Sundararajan Sankaranarayanan,
"Digital Data Acquisition System for Flow Cytometric Analysis,"
in Cytometry (abstract).
Presented at the XX Intl. Congress of the Intl. Society for
Analytical Cytology (ISAC), May 20-25, 2000, Montpellier, France.
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