Chronic intracortical neural recordings using microelectrode arrays coated with PEDOT-TFB.

Unlabelled: Microelectrode arrays have been extensively utilized to record extracellular neuronal activity for brain-machine interface applications. Modifying the microelectrodes with conductive polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) has been reported to be advantageous because it increases the effective surface area of the microelectrodes, thereby decreasing impedance and enhancing charge transfer capacity. However, the long term stability and integrity of such coatings for chronic recordings remains unclear.

Improved Poly(3,4-Ethylenedioxythiophene) (PEDOT) for Neural Stimulation.

Objective: This study compares the stability of three variations of the conductive polymer poly(3,4-ethylenedioxythiophene) or PEDOT for neural micro-stimulation under both in vitro and in vivo conditions. We examined PEDOT films deposited with counter-ions tetrafluoroborate (TFB) and poly(styrenesulfonate) (PSS), and

Pedot: PSS combined with carbon nanotubes (CNTs).

Methods: For the in vitro stability evaluation, implantable micro-wires were coated with the polymers, placed in a vial containing phosphate buffered saline (PBS) under accelerated aging conditions (60°C), and current pulses were applied.

Improving the performance of poly(3,4-ethylenedioxythiophene) for brain-machine interface applications.

Conducting polymers, especially poly(3,4-ethylenedioxythiophene) (PEDOT) based materials, are important for developing highly sensitive and microscale neural probes. In the present work, we show that the conductivity and stability of PEDOT can be significantly increased by switching the widely used counter anion poly(styrenesulfonate) (PSS) to the smaller tetrafluoroborate (TFB) anion during the electrodeposition of the polymer. Time-dependent impedance measurements of polymer modified implantable microwires were conducted in physiological buffer solutions under accelerated aging conditions and the relative stability of PEDOT:PSS and PEDOT:TFB modified microwires was compared over time.

Histocompatibility and in vivo signal throughput for PEDOT, PEDOP, P3MT, and polycarbazole electrodes.

Stimulation and recording of the in vivo electrical activity of neurons are critical functions in contemporary biomedical research and in treatment of patients with neurological disorders. The electrodes presently in use tend to exhibit short effective lifespans due to degradation of signal transmission resulting from the tissue response at the electrode-brain interface, with signal throughput suffering most at the low frequencies relevant for biosignals. To overcome these limitations, new electrode designs to minimize tissue responses, including conducting polymers (CPs) have been explored.

Near-ohmic behavior for conducting polymers: extension beyond PEDOT on gold-plated platinum to other polymer-counterion/substrate combinations.

Conducting polymers constitute a class of materials for which electrochemical and electron transport properties are a function not only of their chemical identity but also of their complex morphology. In this paper, we investigate and compare the frequency dependence behavior of the impedance of poly(3,4-ethylenedioxythiophene), or PEDOT, and that of poly(3,4-ethylenedioxypyrrole), or PEDOP, which are doped with a series of polyatomic anions during electrodeposition. We also contrast the behavior of PEDOT on Pt|Au, Pt, glassy carbon, and gold.

A more informative approach for characterization of polymer monolithic phases: small angle neutron scattering/ultrasmall angle neutron scattering.

Neutron scattering techniques have been used frequently to characterize geological specimens and to determine the structures of glasses and of polymers as solutions, suspensions, or melts. Little work has been reported on their application in determining polymers' structural properties relevant to separations. Here, we present a comparison of characterization results from nitrogen porosimetry and from combined small angle neutron scattering (SANS) and ultrasmall angle neutron scattering (USANS) experiments.

Charge transport in conducting polymers: insights from impedance spectroscopy.

This tutorial review gives a brief introduction to impedance spectroscopy and discusses how it has been used to provide insight into charge transport through conducting polymers, particularly when the polymers are used as electrodes for solution studies or the design of electrodes for biomedical applications. As such it provides both an introduction to the topic and references to both classic and contemporary work for the more advanced reader.