High speed multi-frequency impedance analysis of single biological particle using Maximum Length Sequences

Sun, Tao, Holmes, David, Gawad, Shady, Green, Nicolas G. and Morgan, Hywel (2007) High speed multi-frequency impedance analysis of single biological particle using Maximum Length Sequences. 11th International Conference on Miniaturized Systems for Chemistry and Life Sciences (MicroTAS 2007), Paris, France. 06 - 10 Oct 2007. pp. 1086-1088 .

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.

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Contributors

Author: Nicolas G. Green

Author: Hywel Morgan

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