title: High speed multi-frequency impedance analysis of single particles in a microfluidic cytometer using maximum length sequences.
abstract: A novel impedance spectroscopy technique has been developed for high speed single biological particle analysis. A microfluidic cytometer is used to measure the impedance of single micrometre sized latex particles at high speed across a range of frequencies. The setup uses a technique based on maximum length sequence (MLS) analysis, where the time-dependent response of the system is measured in the time domain and transformed into the impulse response using fast M-sequence transform (FMT). Finally fast Fourier transform (FFT) is applied to the impulse response to give the transfer-function of the system in the frequency domain. It is demonstrated that the MLS technique can give multi-frequency (broad-band) measurement in a short time period (ms). The impedance spectra of polystyrene micro-beads are measured at 512 evenly distributed frequencies over a range from 976.5625 Hz to 500 kHz. The spectral information for each bead is obtained in approximately 1 ms. Good agreement is shown between the MLS data and both circuit simulations and conventional AC single frequency measurements.
authors.affiliation: Nanoscale Systems Integration Group, School of Electronics and Computer Science, University of Southampton, United Kingdom. ts04r@ecs.soton.ac.uk
authors.forename: Tao
authors.initials: T
authors.lastname: Sun
authors.forename: David
authors.initials: D
authors.lastname: Holmes
authors.forename: Shady
authors.initials: S
authors.lastname: Gawad
authors.forename: Nicolas G
authors.initials: NG
authors.lastname: Green
authors.forename: Hywel
authors.initials: H
authors.lastname: Morgan
mesh_terms: D017097:Electric Impedance; D004566:Electrodes; D005434:Flow Cytometry / Q000295:instrumentation / Q000379:methods*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D008863:Microspheres; D008962:Models, Theoretical; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry
chemical_list: D011137:Polystyrenes