Impedance Characterization of Microarray Recording Electrodes in Vitro

Merrill, Daniel R.; Tresco, Patrick A.

doi:10.1109/tbme.2005.856245

Cited by 65 publications

(46 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, the build up of collagen (lower conductivity) and transient micro-hematomas (higher conductivity) are common in epidural implants of flexible electrode arrays [40]. In addition, the electrode array's surface geometry has been shown to influence the thickness of encapsulation tissue beneath the array [41], affecting both the electrode-electrolyte interface impedance [42] and the conductivity of the medium between the electrode and the neural sources [43]. For future electrode designs, we will consider alternate substrate geometries and materials that may increase the performance of the array.…”

Section: Discussionmentioning

confidence: 99%

A low-cost, multiplexedμECoG system for high-density recordings in freely moving rodents

et al. 2016

View full text Add to dashboard Cite

Objective Micro-electrocorticography (μECoG) offers a minimally invasive neural interface with high spatial resolution over large areas of cortex. However, electrode arrays with many contacts that are individually wired to external recording systems are cumbersome and make recordings in freely-behaving rodents challenging. We report a novel high-density 60-electrode system for μECoG recording in freely-moving rats. Approach Multiplexed headstages overcome the problem of wiring complexity by combining signals from many electrodes to a smaller number of connections We have developed a low-cost, multiplexed recording system with 60 contacts at 406 μm spacing. We characterized the quality of the electrode signals using multiple metrics that tracked spatial variation, evoked-response detectability, and decoding value. Performance of the system was validated both in anesthetized animals and freely-moving awake animals. Main results We recorded μECoG signals over the primary auditory cortex, measuring responses to acoustic stimuli across all channels. Single-trial responses had high signal-to-noise ratios (up to 25 dB under anesthesia), and were used to rapidly measure network topography within ~10 seconds by constructing all single-channel receptive fields in parallel. We characterized evoked potential amplitudes and spatial correlations across the array in the anesthetized and awake animals. Recording quality in awake animals was stable for at least 30 days. Finally, we used these responses to accurately decode auditory stimuli on single trials. Significance This study introduces (1) a μECoG recording system based on practical hardware design and (2) a rigorous analytical method for characterizing the signal characteristics of μECoG electrode arrays. This methodology can be applied to evaluate the fidelity and lifetime of any μECoG electrode array. Our μECoG-based recording system is accessible and will be useful for studies of perception and decision-making in rodents, particularly over the entire time course of behavioral training and learning.

show abstract

Section: Discussionmentioning

confidence: 99%

A low-cost, multiplexedμECoG system for high-density recordings in freely moving rodents

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Likewise, failing electrode arrays produce low yields. It has been shown that impedance spectroscopy provides insight to the fundamental aspects of biotic and abiotic interactions that affect array performance (Grill and Mortimer, 1994; Merrill and Tresco, 2005; Ludwig et al, 2006, 2011; Williams et al, 2007; McConnell et al, 2009a; Karumbaiah et al, 2013). Combining standard electrophysiological measurements with abiotic and biotic analysis can produce comprehensive insight to electrode failure.…”

Section: Introductionmentioning

confidence: 99%

Abiotic-biotic characterization of Pt/Ir microelectrode arrays in chronic implants

et al. 2014

View full text Add to dashboard Cite

Pt/Ir electrodes have been extensively used in neurophysiology research in recent years as they provide a more inert recording surface as compared to tungsten or stainless steel. While floating microelectrode arrays (FMA) consisting of Pt/Ir electrodes are an option for neuroprosthetic applications, long-term in vivo functional performance characterization of these FMAs is lacking. In this study, we have performed comprehensive abiotic-biotic characterization of Pt/Ir arrays in 12 rats with implant periods ranging from 1 week up to 6 months. Each of the FMAs consisted of 16-channel, 1.5 mm long, and 75 μm diameter microwires with tapered tips that were implanted into the somatosensory cortex. Abiotic characterization included (1) pre-implant and post-explant scanning electron microscopy (SEM) to study recording site changes, insulation delamination and cracking, and (2) chronic in vivo electrode impedance spectroscopy. Biotic characterization included study of microglial responses using a panel of antibodies, such as Iba1, ED1, and anti-ferritin, the latter being indicative of blood-brain barrier (BBB) disruption. Significant structural variation was observed pre-implantation among the arrays in the form of irregular insulation, cracks in insulation/recording surface, and insulation delamination. We observed delamination and cracking of insulation in almost all electrodes post-implantation. These changes altered the electrochemical surface area of the electrodes and resulted in declining impedance over the long-term due to formation of electrical leakage pathways. In general, the decline in impedance corresponded with poor electrode functional performance, which was quantified via electrode yield. Our abiotic results suggest that manufacturing variability and insulation material as an important factor contributing to electrode failure. Biotic results show that electrode performance was not correlated with microglial activation (neuroinflammation) as we were able to observe poor performance in the absence of neuroinflammation, as well as good performance in the presence of neuroinflammation. One biotic change that correlated well with poor electrode performance was intraparenchymal bleeding, which was evident macroscopically in some rats and presented microscopically by intense ferritin immunoreactivity in microglia/macrophages. Thus, we currently consider intraparenchymal bleeding, suboptimal electrode fabrication, and insulation delamination as the major factors contributing toward electrode failure.

show abstract

“…C is mainly due to the parasitic shunt capacitance of the MCS cable (128 pF) while R ‐value is different in the two configurations. Considering the commercial setup, R is the MEA1060 output resistance (300 Ω) while in the custom system it is mainly given by the source impedance, which results from electrode impedance and cell coupling/adhesion and exceeds 1 MΩ (Merril and Tresco, 2005). Therefore, f cutoff is equal to 4 MHz for the commercial setup (no signal components are cut) and to 1.2 kHz for the custom recording equipment, which is within neuronal spike frequency content.…”

Section: Resultsmentioning

confidence: 99%

A novel environmental chamber for neuronal network multisite recordings

Biffi¹,

Regalia²,

Ghezzi³

et al. 2012

Biotech & Bioengineering

View full text Add to dashboard Cite

Environmental stability is a critical issue for neuronal networks in vitro. Hence, the ability to control the physical and chemical environment of cell cultures during electrophysiological measurements is an important requirement in the experimental design. In this work, we describe the development and the experimental verification of a closed chamber for multisite electrophysiology and optical monitoring. The chamber provides stable temperature, pH and humidity and guarantees cell viability comparable to standard incubators. Besides, it integrates the electronics for long-term neuronal activity recording. The system is portable and adaptable for multiple network housings, which allows performing parallel experiments in the same environment. Our results show that this device can be a solution for long-term electrophysiology, for dual network experiments and for coupled optical and electrical measurements.

show abstract

Impedance Characterization of Microarray Recording Electrodes in Vitro

Cited by 65 publications

References 32 publications

A low-cost, multiplexedμECoG system for high-density recordings in freely moving rodents

A low-cost, multiplexedμECoG system for high-density recordings in freely moving rodents

Abiotic-biotic characterization of Pt/Ir microelectrode arrays in chronic implants

A novel environmental chamber for neuronal network multisite recordings

Contact Info

Product

Resources

About