title: Electrochemical noise and impedance of Au electrode/electrolyte interfaces enabling extracellular detection of glioma cell populations.
abstract: Microelectrode arrays (MEA) record extracellular local field potentials of cells adhered to the electrodes. A disadvantage is the limited signal-to-noise ratio. The state-of-the-art background noise level is about 10 μVpp. Furthermore, in MEAs low frequency events are filtered out. Here, we quantitatively analyze Au electrode/electrolyte interfaces with impedance spectroscopy and noise measurements. The equivalent circuit is the charge transfer resistance in parallel with a constant phase element that describes the double layer capacitance, in series with a spreading resistance. This equivalent circuit leads to a Maxwell-Wagner relaxation frequency, the value of which is determined as a function of electrode area and molarity of an aqueous KCl electrolyte solution. The electrochemical voltage and current noise is measured as a function of electrode area and frequency and follow unambiguously from the measured impedance. By using large area electrodes the noise floor can be as low as 0.3 μVpp. The resulting high sensitivity is demonstrated by the extracellular detection of C6 glioma cell populations. Their minute electrical activity can be clearly detected at a frequency below about 10 Hz, which shows that the methodology can be used to monitor slow cooperative biological signals in cell populations.
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
authors.forename: Paulo R F
authors.initials: PR
authors.lastname: Rocha
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Schlett
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Kintzel
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.|Dermatology Clinic, University Medicine of the Johannes-Gutenberg Universität Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Mailänder
authors.affiliation: Electrical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, Netherlands.
authors.forename: Lode K J
authors.initials: LK
authors.lastname: Vandamme
authors.affiliation: Natural and Medical Sciences Institute, Markwiesenstrasse 55, D-72770 Reutlingen, Germany.
authors.forename: Gunther
authors.initials: G
authors.lastname: Zeck
authors.affiliation: IT-Instituto de Telecomunicações, Av. Rovisco, Pais, 1, 1049 - 001 Lisboa, Portugal.|Universidade do Algarve, FCT, 8005-139 Faro, Portugal.
authors.forename: Henrique L
authors.initials: HL
authors.lastname: Gomes
authors.affiliation: Life Science Department, Università di Modena e Reggio Emilia, Via Campi 103, I-41125 Modena, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Biscarini
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
authors.forename: Dago M
authors.initials: DM
authors.lastname: de Leeuw
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000503:physiopathology; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002470:Cell Survival; D025802:Electric Capacitance; D017097:Electric Impedance; D055724:Electrophysiological Phenomena; D005910:Glioma / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D006046:Gold; D006801:Humans; D008839:Microelectrodes; D051381:Rats; D059629:Signal-To-Noise Ratio
chemical_list: D006046:Gold