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 - Köhler, Tim A1 - Wölfel, Maximilian A1 - Ciba, Manuel A1 - Bochtler, Ulrich A1 - Thielemann, Christiane T1 - Terrestrial Trunked Radio (TETRA) exposure of neuronal in vitro networks JF - Environmental Research N2 - Terrestrial Trunked Radio (TETRA) is a worldwide common mobile communication standard, used by authorities and organizations with security tasks. Previous studies reported on health effects of TETRA, with focus on the specific pulse frequency of 17.64 Hz, which affects calcium efflux in neuronal cells. Likewise among others, it was reported that TETRA affects heart rate variability, neurophysiology and leads to headaches. In contrast, other studies conclude that TETRA does not affect calcium efflux of cells and has no effect on people's health. In the present study we examine whether TETRA short- and long-term exposure could affect the electrophysiology of neuronal in vitro networks. Experiments were performed with a carrier frequency of 395 MHz, a pulse frequency of 17.64 Hz and a differential quaternary phase-shift keying (π/4 DQPSK) modulation. Specific absorption rates (SAR) of 1.17 W/kg and 2.21 W/kg were applied. In conclusion, the present results do not indicate any effect of TETRA exposure on electrophysiology of neuronal in vitro networks, neither for short-term nor long-term exposure. This applies to the examined parameters spike rate, burst rate, burst duration and network synchrony. KW - Neuronales Netz Y1 - 2018 U6 - https://doi.org/10.1016/j.envres.2017.12.007 VL - 2018 IS - 162 SP - 1 EP - 7 ER - TY - CHAP A1 - Köhler, Tim A1 - Wölfel, Maximilian A1 - Bochtler, Ulrich A1 - Thielemann, Christiane T1 - TETRA specific long-term exposure of neuronal in vitro networks T2 - BioEM2016 KW - Neuronales Netz Y1 - 2016 ER - TY - THES A1 - Köhler, Tim T1 - Auswirkungen elektromagnetischer Strahlung auf die elektrophysiologischen Eigenschaften neuronaler und kardialer Zellnetzwerke KW - Neuronales Netz KW - Elektromagnetische Strahlung Y1 - 2019 UR - https://tuprints.ulb.tu-darmstadt.de/id/eprint/8544 ER -