TY - JOUR A1 - Flachs, Dennis A1 - Köhler, Tim A1 - Thielemann, Christiane T1 - Transparent poly(3,4-ethylenedioxythiophene)-based microelectrodes for extracellular recording JF - Biointerphases N2 - It is well known that at the interface between neuronal tissue and recording electrode low electrical impedance is required. However, if simultaneous optical detection or stimulation is an issue, good optical transmittance of the electrode material is desirable as well. State-of-the-art titanium nitride electrodes provide superior low impedance compared to gold or iridium, but are nontransparent. Transparent electrode materials like the transparent conducting oxide, indium tin oxide (ITO), or graphene offer high light transmittance (>80%) but reveal relatively high impedance. In this paper, the authors propose the conducting polymer poly(3,4-ethylenedioxythiophene) with the counter ion NO−3 as the electrode material for low impedance and good optical transmittance properties. The polymer is electrochemically deposited onto ITO improving the relatively high impedance of ITO. This multilayer electrode allows not only for electrophysiological recordings of cardiomyocytes but also for monitoring of cell contraction under the microscope. Electrochemical impedance spectroscopy and action potential recordings reveal that the new transparent electrodes are a good compromise in terms of low impedance and transparency if deposition parameters are optimized. KW - Impedanzspektroskopie KW - Mikroelektrode Y1 - 2018 U6 - https://doi.org/10.1116/1.5041957 VL - 2018 IS - 13:041008 SP - 1 EP - 1 ER - TY - JOUR A1 - Flachs, Dennis A1 - Ciba, Manuel T1 - Cell-based sensor chip for neurotoxicity measurements in drinking water JF - Lékař a technika - Clinician and Technology N2 - Our drinking water contains residues of pharmaceuticals. A sub-group of these contaminants are neuro-active substances, the antiepileptic carbamazepine being one of the most relevant. For assessment of the neurotoxicity of this drug at a sub-therapeutic level, a cell-based sensor chip platform has been realized and characterized. For this purpose, a microelectrode array chip was designed and processed in a clean room and optimized in terms of low processing costs and good recording properties. For characterization of the system neuronal cells were plated on microelectrode array chips and electrical activity was measured as a function of applied carbamazepine concentration. We found that the relative spike rate decreased with increasing drug concentration resulted in IC50 values of around 36 μM. This value is five orders of magnitude higher than the maximal dose found in drinking water. IC50 values for burst rate, burst duration and synchrony were slightly higher, suggesting spike rate being a more sensitive parameter to carbamazepine. KW - Microelectrode array KW - Carbamazepine KW - Neurotoxicity KW - Cell-based biosensor KW - Mikroelektrode KW - Array KW - Biosensor KW - Neurotoxizität Y1 - 2016 VL - 46 IS - 2 SP - 46 EP - 50 ER -