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Co-ordinated detection of microparticles using tunable resistive pulse sensing and fluorescence spectroscopy

Peter Hauer, Eric C. Le Ru and Geoff R. Willmott
Biomicrofluidics 9, 014110 (2015)

Tunable resistive pulse sensing (TRPS) has emerged as a useful tool for particle-by-particle detection and analysis of microparticles and nanoparticles as they pass through a pore in a thin stretchable membrane. We have adapted a TRPS device in order to conduct simultaneous optical measurements of particles passing through the pore. High-resolution fluorescence emission spectra have been recorded for individual 1.9 m diameter particles at a sampling period of 4.3 ms. These spectra are time-correlated with RPS pulses in a current trace sampled every 20 s. The flow rate through the pore, controlled by altering the hydrostatic pressure, determines the rate of particle detection. At pressures below 1 kPa, more than 90% of fluorescence and RPS events were matching. At higher pressures, some peaks were missed by the fluorescence technique due to the difference in sampling rates. This technique enhances the particle-by-particle specificity of conventional RPS measurements and could be useful for a range of particle characterization and bioanalysis applications.

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