Paper
8 May 2014 Particle detection from spatially modulated fluorescence signals
Siegfried W. Kettlitz, Carola Moosmann, Sebastian Valouch, Uli Lemmer
Author Affiliations +
Abstract
Flow cytometry relies on the detection of cells selectively stained with fluorescence markers. Optically they can be detected as fluorescence particles. The use of microuidics offers a wide range of benefits over traditional flow cytometer designs but when replacing expensive components with inexpensive counterparts the sensitivity of the instrument suffers. To increase the sensitivity of the detection system, spatial modulation has been proposed. Spatial modulation is implemented via _ne pitched shadow masks close to the microuidic channel which generate a signal pattern when a fluorescent particle passes by. Using a _ne pitch and long total length for the pattern a high spatial resolution and long total exposure time are combined. Particle detection from local maxima is not directly possible with spatially modulated signals due to the jagged pulse shape. We compare the performance of different approaches for particle detection from local maxima. Matched filtering and the derivative of the correlation signal provide either a good peak-signal-to-noise ratio (PSNR) or a high spatial resolution. But both approaches suffer from low dynamic range due to side maxima. We derive the solution for a minimum- mean-square-error (MMSE) filter which transforms the modulated pulse shape into a target pulse shape with a single strong maximum. We investigate the performance of the MMSE filter and find that it provides tunable suppression of noise and side maxima along with a high spatial resolution. The use of the MMSE filter therefore is an ideal choice for particle detection from spatially modulated signals.
© (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Siegfried W. Kettlitz, Carola Moosmann, Sebastian Valouch, and Uli Lemmer "Particle detection from spatially modulated fluorescence signals", Proc. SPIE 9129, Biophotonics: Photonic Solutions for Better Health Care IV, 91291B (8 May 2014); https://doi.org/10.1117/12.2052169
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KEYWORDS
Particles

Modulation

Signal detection

Interference (communication)

Signal to noise ratio

Electronic filtering

Spatial resolution

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