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Eis guide v2 ELECTRICAL IMPEDANCE SPECTROSCOPY Revision www micronit com CCONTENTS CONTENTS INTRODUCTION The design EIS CAPABILITIES EIS system set-up and testing Results of EIS measurements for sample beads Concluding remarks References and acknowledgeme

ELECTRICAL IMPEDANCE SPECTROSCOPY Revision www micronit com CCONTENTS CONTENTS INTRODUCTION The design EIS CAPABILITIES EIS system set-up and testing Results of EIS measurements for sample beads Concluding remarks References and acknowledgements Aside Recommended cleaning technique CUSTOM EIS DESIGNS www micronit com CINTRODUCTION The use of electrical impedance spectroscopy to detect and characterise cells can work as an e ?ective in-line monitoring tool for micro uidic devices There are several key advantages of this technique in the micro uidic environment including ? Fast throughput cells s ? Multiple parameter analysis ? Integrates well with other analysis methods i e optical detection ? Label free analysis method THE DESIGN All the Electrical Impedance Spectroscopy EIS chips are designed by Micronit and made of borosilicate glass and an inert interstitial layer of dry ?lm resist for well-de ?ned channels ideal for uniform ow through sensing region These devices are delivered in a polymer PP cartridge of x mm which is compatible with the Fluidic Connect PRO chip holder Our standard design for EIS -chips has a straight through channel m deep and m wide making it suitable for complete blood count type applications There are two sets of double electrodes with planar separation of m and m depth separation as based on channel depth A cross sectional schematic of the electrode layout can be seen in Figure Figure Cross sectional view of electrode layout www micronit com CDo you want di ?erent features for your EIS -chips ? More inlets or outlets ? Di ?erent channel dimension or electrode layouts ? Extra functionalities or additional electrodes Contact us to have your own custom made EIS -chips See page for more information www micronit com CEIS CAPABILITIES Information such as cell size type discrimination and other quantitative characteristic information can be measured for biological systems using impedance spectroscopy EIS o ?ers the advantage of acquiring this information from cells without the need to label them as would be needed for characterisation using tools such as uorescence microscopy A standard cell can be considered as a membrane enclosing cytoplasm which contains the nucleus of the cell as well as other subcellular components a schematic of this can be seen to the left of Figure All these di ?erent parts of the cell have di ?erent dielectric properties For example the cell membrane is generally not conductive since it consists of a phospholipid bilayer with various channels formed by large proteins In contrast the cytoplasm of the cell typically contains a high concentration of ions which makes it very conductive Putting these things together an electrical equivalent circuit model of the cell can be created as shown to the right in Figure Figure Schematics of both a cell and a simpli ?ed circuit equivalent Image courtesy of Zurich Instruments The electrical equivalent circuit model can be used to represent the various components such as the membrane as a capacitor and resistor in parallel and the cytoplasm as a single resistor Finally the surrounding environment can be