Zirconium dioxide nanolayer passivated impedimetric sensors for cell-based assays

Drago Sticker, Mario Rothbauer, Verena Charwat, Jan Steinkuehler, Ole Bethge, Emmerich Bertagnolli, Heinz D. Wanzenboeck, Peter Ertl

    Research output: Contribution to journalArticlepeer-review

    Abstract

    To advance existing in vitro cell impedance spectroscopy and improve reliability of impedimetric sensorsfor cell analysis, we have electrically insulated interdigitated microelectrodes using the high-k biomate-rial zirconium dioxide (ZrO2). We report the smallest passivation thickness to electrode distance ratio of10−3using atomic layer deposition resulting in electrically insulated metal oxide films of 15 nm thick-ness. For the first time the influence of the insulation on sensor performance is experimentally andtheoretically analyzed using numerical simulations. In addition an equivalent electrical circuit modelwas established and validated using non-linear least square fitting. Results of the computational simu-lations revealed improved electrical current distribution across the electrically insulated interdigitatedelectrode structures in comparison to open (not passivated) electrodes. Furthermore, we found lineardecrease of current density in z-direction within 5 m distance from the sensor surface in the presenceof ZrO2nanocoatings is ideally suited to assess confluent cell layers. Final practical application of theZrO2nanolayer passivated impedimetric sensors is demonstrated for nanotoxicological investigations,where sensitivity and repeatability are crucial parameters for cell analysis. Results of our study show thatthe reproducible and standardizable deposition of a uniform metal oxide nanocoating improves currentdensity distributions, has no performance drawbacks compared to open sensors and enables sensitivedetection of protein-coating effects on cytotoxic silica nanoparticles. The presented novel sensor designallows for the integration of alternative electrode materials such as aluminum enabling cost-effectivefabrication of large-volume sensor arrays
    Original languageEnglish
    JournalSensors and Actuators B-Chemical
    DOIs
    Publication statusPublished - 5 Jul 2015

    Research Field

    • Biosensor Technologies

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