In vivo and in vitro electrochemical impedance spectroscopy analysis of acute and chronic intracranial electrodes

Invasive intracranial electrodes are used in both clinical and research applications for recording and stimulation of brain tissue, providing essential data in acute and chronic contexts. The impedance characteristics of the electrode–tissue interface (ETI) evolve over time and can change dramatically relative to pre-implantation baseline. Understanding how ETI properties contribute to the recording and stimulation characteristics of an electrode can provide valuable insights for users who often do not have access to complex impedance characterizations of their devices. In contrast to the typical method of characterizing electrical impedance at a single frequency, we demonstrate a method for using electrochemical impedance spectroscopy (EIS) to investigate complex characteristics of the ETI of several commonly used acute and chronic electrodes. We also describe precise modeling strategies for verifying the accuracy of our instrumentation and understanding device–solution interactions, b..., Electrochemical impedance spectroscopy- This technique involves measurement of an electrochemical interface by applying a sinusoidal voltage perturbation across a range of frequencies. For potentiostatic modulation, a single perturbation amplitude is maintained across the frequency spectrum, typically lower than amplitudes used in biological stimulation. The frequency range chosen for these measurements was 10 Hz-100 kHz, with an amplitude of 0.01 V. Data were sampled at 39 frequency intervals across this spectrum, or 9.5/dec. Using the complex impedance values obtained by our instrument, a fitted model was created to approximate the components of the biotic-abiotic interface.
Data collection- Data were primarily collected using a Palmsens4 Potentiostat instrument in Electrochemical Impedance Spectroscopy mode, both in vitro and in vivo in non-human primates (NHP). NHP subjects included two adult male rhesus macaque monkeys chronically implanted with both penetrating deep brain stimulat..., , # Electrochemical Impedance Spectroscopy (EIS) recordings of a series of implantable neural electrodes

This dataset contains both in-vitro and in-vivo EIS recordings of implantable electrodes designed for recording and stimulation of human and animal brain tissue. In-vitro data were recorded in up to four different electrolyte solutions and two different electrode configurations. Solutions included phosphate-buffered saline (PBS), artificial cerebrospinal fluid (ACSF) and salt solutions matching gray and white matter conductivities, in both two and three-electrode configurations. The counter electrode used in in-vivo measurements consisted of a titanium screw or titanium rod embedded in a chronically affixed skull cap, with its tip contacting brain tissue. Counter-electrodes used in vitro included a titanium screw similar to that used in vivo as well as platinum wire (7.5 cm length/0.5 mm diameter) and platinum foil (625 mm^2 surface area). When a 3-electrode measurement system was app...