Abstract
This paper proposes a simple approach to optimize the operating frequency band of a lab-on-a-chip based on bio-impedance cytometry for a single cell. It mainly concerns applications in low-conductivity media. Bio-impedance allows for the characterization of low cell concentration or single cells by providing an electrical signature. Thus, it may be necessary to perform impedance measurements up to several tens of megahertz in order to extract the internal cell signature. In the case of single cells, characterization is performed in a very small volume down to 1 pL. At the same time, measured impedances increase from tens of kilo-ohms for physiological liquids up to several mega-ohms for low conductivity media. This is, for example, the case for water analysis. At frequencies above hundreds of kilohertz, parasitic effects, such as coupling capacitances, can prevail over the impedance of the sample and completely short-circuit measurements. To optimize the sensor under these conditions, a complete model of a cytometry device was developed, including parasitic coupling capacitances of the sensor to take into account all the impedances. It appears that it is possible to increase the pass band by optimizing track geometries and placement without changing the sensing area. This assumption was obtained by measuring and comparing electrical properties of yeast cells in a low-conductivity medium (tap water). Decreased coupling capacitance by a factor higher than 10 was obtained compared with a previous non-optimized sensor, which allowed for the impedance measurement of all electrical properties of cells as small as yeast cells in a low-conductivity medium.
Highlights
For many years research has focused on the development of lab-on-a-chip devices for biomedical applications [1] and applications such as the analysis of water quality [2]
A method to optimize the frequency band of a cytometry biosensor for low conductivity media
A method to optimize the frequency band of a cytometry for lowcover conductivity media analysis was described
Summary
Research has focused on the development of lab-on-a-chip devices for biomedical applications [1] and applications such as the analysis of water quality [2]. It is even possible to detect and characterize a single cell or microparticle [6] Bioimpedance measurement, such as bioimpedance spectroscopy (BIS), permits the characterization of physiological properties of cells and bacteria over a large range of applications from human tissues analysis to the detection of bacteria or microorganisms. This technique is widely used as a diagnostic tool [7] or for medical imaging [8]. It remains difficult to use in the case of low concentration
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