PEDOT:PSS coated gold nanopillar microelectrodes for neural interfaces

Nick, Christoph; Thielemann, Christiane; Schlaak, Helmut F.

doi:10.1109/3m-nano.2014.7057309

Cited by 4 publications

(4 citation statements)

References 41 publications

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“…This will not only fundamentally enable the next-generation bioelectrical sensing and actuation but also implore the need to characterize electrodes of various sizes and materials/coatings at subcellular levels. Considerable studies on modeling the electrode–electrolyte interfaces have established our understanding of the effects of various electrode properties, such as electrode materials and sizes, on the biosensing and electrical stimulation through MEAs. ,,,− Previous investigations have also demonstrated that non-uniform distribution of current near edges of electrodes often causes early electrode degradations. ,, Recently, conducting polymer-coated electrodes have been considered as an ideal alternative to conventional metal or metal-oxide electrodes. ,, Particularly, PEDOT:PSS-coated electrodes (>10 μm) have been shown to significantly reduce the interfacial impedance and thermal noise while maintaining long-term electrochemical stability and excellent biocompatibility due to its mixed electronic/ionic conductivity. ,,− ,,− In addition, the elastic nature of PEDOT:PSS reduces the mechanical mismatch at the interface between electrodes and cells, enhancing devices’ biocompatibility and decreasing their invasiveness . However, despite several decades of research, the performance limitations, electrochemical characteristics, and electrode–electrolyte interfaces attributed to electrodes of varying compositions, sizes, and polymer coatings have not been systematically characterized, especially for electrodes of subcellular sizes that exhibit substantial edge-to-area ratios.…”

Section: Introductionmentioning

confidence: 99%

Impedance Characterization and Modeling of Subcellular to Micro-sized Electrodes with Varying Materials and PEDOT:PSS Coating for Bioelectrical Interfaces

Wang

Jung

Lee

et al. 2021

ACS Appl. Electron. Mater.

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Electrode-to-cell/tissue interfaces with high biocompatibility, low impedance, and long-term chemical and mechanical stability are of paramount importance in numerous biological and biomedical applications. For meticulous monitoring of biological parameters, there is a rapidly growing interest in sensing at subcellular levels with radically improved spatiotemporal resolution, which necessitates ultra-miniaturized electrodes with significant reduction in electrode contact sizes. Such aggressive electrode downsizing inevitably impacts the electrochemical interfaces, with the consequences still poorly understood. This paper reports the first systematic analysis of the interfacial electrochemical impedance spectroscopy of electrodes comprising a variety of biocompatible electrode materials consisting of gold (Au), platinum (Pt), indium tin oxide, and titanium nitride (TiN) coated with/without an organic polymer, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), with electrode diameters (D) ranging from millimeter to subcellular (<10 μm) dimensions. PEDOT:PSS-coated electrodes have greater Faradaic charge-transfer capability and capacitive coupling compared to their uncoated counterparts. At D = 10–200 μm, the PEDOT:PSS coating reduces the electrode interfacial impedance at 1 kHz by up to ×101.6, while at D > 200 μm, the effect is lessened due to the dominance of solution, or bulk electrolyte, and routing resistance. The low interfacial impedance of PEDOT:PSS-coated electrodes makes them promising candidates for next-generation bioelectrical interfaces with subcellular spatial resolution.

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Section: Introductionmentioning

confidence: 99%

Impedance Characterization and Modeling of Subcellular to Micro-sized Electrodes with Varying Materials and PEDOT:PSS Coating for Bioelectrical Interfaces

Wang

Jung

Lee

et al. 2021

ACS Appl. Electron. Mater.

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“…To verify the linearity and resolution, we swept 20 codes around the zero-crossing and measured an LSB of 15.3 nA with a DNL of 0.13 LSB over that range (Figure 4b). Typically, such small currents are not biologically relevant for neuromodulation systems; however, microelectrode electroplating current levels can be on the order of 100 nA [18]. Note that the input bias current of the amplifier was roughly 10 µA, but this offset was canceled through DAC calibration.…”

Section: System Transfer Functionmentioning

confidence: 99%

MEDUSA: A Low-Cost, 16-Channel Neuromodulation Platform with Arbitrary Waveform Generation

Tala

Johnson

2020

Electronics

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Neural stimulation systems are used to modulate electrically excitable tissue to interrogate neural circuit function or provide therapeutic benefit. Conventional stimulation systems are expensive and limited in functionality to standard stimulation waveforms, and they are bad for high frequency stimulation. We present MEDUSA, a system that enables new research applications that can leverage multi-channel, arbitrary stimulation waveforms. MEDUSA is low cost and uses commercially available components for widespread adoption. MEDUSA is comprised of a PC interface, an FPGA for precise timing control, and eight bipolar current sources that can each address up to 16 electrodes. The current sources have a resolution of 15.3 nA and can provide ±5 mA with ±5 V compliance. We demonstrate charge-balancing techniques in vitro using a custom microelectrode. An in vivo strength-duration curve for earthworm nerve activation is also constructed using MEDUSA. MEDUSA is a multi-functional neuroscience research tool for electroplating microelectrodes, performing electrical impedance spectroscopy, and examining novel neural stimulation protocols.

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“…13 However, the smooth gold surfaces and the lack of chemically bound PEDOT rendered these nanorods susceptible to delamination. Ganji et al 14 and Nick et al 10 addressed the delamination and stability of PEDOT:PSS coatings in an examination of spincoated, electrodeposited, and drop-casted PEDOT:PSS films on nanostructured gold microelectrodes. The addition of nanopillar structures on gold increased the adhesion primarily by increasing the total interfacial area.…”

mentioning

confidence: 99%

“…Traditionally, biocompatible metals like platinum, platinum–iridium, and stainless steel are used in clinical applications that require electrophysiological recording and stimulation. , However, small metal electrodes suffer from high electrochemical impedance with biological tissue which increases the electrochemical noise of electrodes and impairs their sensitivity. , Conductive polymers offer a solution that can be integrated with current microelectrode fabrication techniques, both lowering impedance and creating a surface more mechanically compatible with the surrounding tissue. , In particular, the mixed electronic/ionic conduction mechanism of the polyelectrolyte complex poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) exhibits a high volumetric capacitance and, as a hydrated solid, low impedance with biological tissues. Electrodeposition or spin-coating of PEDOT:PSS onto gold microelectrodes lowers the impedance and increases charge injection capacity compared to bare metal electrodes. ,− Polymer-coated metal electrodes seem to offer a biocompatible option for long-term neural electrodes. While studies have shown that the electrodes are stable under biologically relevant conditions, the polymerswhich are physisorbedare not bound chemically to the gold surface.…”

mentioning

confidence: 99%

Synthesis of PEDOT:PSS Brushes Grafted from Gold Using ATRP for Increased Electrochemical and Mechanical Stability

Tuermer-Lee,

Lim,

et al. 2023

ACS Macro Lett.

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We report PEDOT:PSS brushes grafted from gold using surface-initiated atom-transfer radical polymerization (SI-ATRP) which demonstrate significantly enhanced mechanical stability against sonication and electrochemical cycling compared to spincoated analogues as well as lower impedances than bare gold at frequencies from 0.1 to 10 5 Hz. These results suggest SI-ATRP PEDOT:PSS to be a promising candidate for use in microelectrodes for neural activity recording. Spin-coated, electrodeposited, and drop-cast PEDOT:PSS have already been shown to reduce impedance and improve biocompatibility of microelectrodes, but the lack of strong chemical bonds of the physisorbed polymer film to the metal leads to disintegration under required operational stresses including cyclic mechanical loads, abrasion, and electrochemical cycling. Rather than modifying the metal electrode or introducing cross-linkers or other additives to improve the stability of the polymer film, this work chemically tethers the polymer to the surface, offering a simple, scalable solution for functional bioelectronic interfaces.

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PEDOT:PSS coated gold nanopillar microelectrodes for neural interfaces

Cited by 4 publications

References 41 publications

Impedance Characterization and Modeling of Subcellular to Micro-sized Electrodes with Varying Materials and PEDOT:PSS Coating for Bioelectrical Interfaces

Impedance Characterization and Modeling of Subcellular to Micro-sized Electrodes with Varying Materials and PEDOT:PSS Coating for Bioelectrical Interfaces

MEDUSA: A Low-Cost, 16-Channel Neuromodulation Platform with Arbitrary Waveform Generation

Synthesis of PEDOT:PSS Brushes Grafted from Gold Using ATRP for Increased Electrochemical and Mechanical Stability

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