Evaluation of microelectrode materials for direct-current electrocorticography

Abstract

Our experimental results indicate that IrOx-based microelectrodes, particularly with composite layers of nanostructures, are excellent in all of the common evaluation characteristics both in vitro and in vivo and are most suitable for multimodal monitoring applications. Pt electrodes suffer high current-induced polarization, but have acceptable long-term stability suitable for DC-ECoG. Major significance. The results of this study provide quantitative data on the electrical properties of microelectrodes with commonly-used materials and will be valuable for development of neural recordings inclusive of low frequencies.

Terminal spreading depolarization and electrical silence in death of human cerebral cortex

“…Both subdural and intraparenchymal Pt/Ir electrodes show a good safety profile in humans, 27,42 but it should be noted that electrode polarization of platinum causes significant distortion and underestimation of the true amplitude of the negative DC shift. 43,44 Moreover, platinum displays a strong catalytic capacity for many chemical reactions in biological media. Thus, recordings from intracranial platinum electrodes reflect not only the DC potential of SD, but likely also the signals of p ti O 2 and pH.…”

A User-Configurable Headstage for Multimodality Neuromonitoring in Freely Moving Rats

“…The multimodal neural probe composed of microsensors for ECoG, PbrO 2 , temperature, and rCBF measurement (Li et al, 2016a ). The ECoG recording electrode with on-probe reference electrode was optimized for DC-ECoG recording to have a very low polarization rate and stable baseline for detecting the DC shift of spreading depolarization (Li et al, 2016a , b ). The PbrO 2 microsensors are electrochemical microsensors with 3 electrodes configuration (Li et al, 2016a ).…”

“…In this paper, we describe a method for realizing multimodal brain monitoring in freely moving rats by using a cost and time effective headstage. To demonstrate this, we designed a headstage for our previously described multimodal neural probe, which is capable of sensing multiple physiological, biochemical, and electrophysiological parameters simultaneously (Li et al, 2009 , 2012 , 2015 , 2016a , b ; Li and Narayan, 2014 ). This headstage has allowed us to transcend multimodal brain monitoring from anesthetized animals (Li et al, 2016a ) to freely moving animals.…”

High-resolution mapping of infraslow cortical brain activity enabled by graphene microtransistors

“…Importantly, gSGFETs record significantly higher amplitude for the CSD events (-13.3 ± 1.8 mV) in comparison with gold (-4.7 ± 1.6 mV) and platinum black (-3.0 ± 0.7 mV) microelectrodes. Figure 3b highlights these two intrinsic limitations of microelectrode technology for the measurement of ISA: polarization-induced drift and signal filtering 20,23 . The drift of the baseline potential superimposed over the huge voltage offsets is problematic as it can lead to saturation of the amplifiers used to record the signal.…”

“…However, due to the toxicity of silver, the use of such electrodes for human or chronic animal in vivo monitoring is not an option 19 . This has fostered the search for alternative microelectrode materials with low impedance and drift although none has yet been found capable of offering comparable performance as Ag/AgCl electrodes 20 . So, ISA recordings in humans are currently performed with platinum electrodes, which challenge CSD detection due to artifacts and transients 21 .…”