Issue 1, 2012

Simultaneous high speed optical and impedance analysis of single particles with a microfluidic cytometer

Abstract

We describe a microfluidic cytometer that performs simultaneous optical and electrical characterisation of particles. The microfluidic chip measures side scattered light, signal extinction and fluorescence using integrated optical fibres coupled to photomultiplier tubes. The channel is 80 μm high and 200 μm wide, and made from SU-8 patterned and sandwiched between glass substrates. Particles were focused into the analysis region using 1-D hydrodynamic focusing and typical particle velocities were 0.1 ms−1. Excitation light is coupled into the detection channel with an optical fibre and focused into the channel using an integrated compound air lens. The electrical impedance of particles is measured at 1 MHz using micro-electrodes fabricated on the channel top and bottom. This data is used to accurately size the particles. The system is characterised using a range of different sized polystyrene beads (fluorescent and non-fluorescent). Single and mixed populations of beads were measured and the data compared with a conventional flow cytometer.

Graphical abstract: Simultaneous high speed optical and impedance analysis of single particles with a microfluidic cytometer

Article information

Article type
Paper
Submitted
19 Aug 2011
Accepted
20 Oct 2011
First published
03 Nov 2011

Lab Chip, 2012,12, 118-126

Simultaneous high speed optical and impedance analysis of single particles with a microfluidic cytometer

D. Barat, D. Spencer, G. Benazzi, M. C. Mowlem and H. Morgan, Lab Chip, 2012, 12, 118 DOI: 10.1039/C1LC20785G

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