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Resistive and reactive changes to the impedance of intracortical microelectrodes can be mitigated with polyethylene glycol under acute in vitro and in vivo settings.

Sommakia S, Gaire J, Rickus JL, Otto KJ - Front Neuroeng (2014)

Bottom Line: We show that exposure to a model protein solution in vitro and acute implantation result in both resistive and capacitive changes to electrode impedance, rather than purely resistive changes.We also show that applying 4000 MW polyethylene glycol (PEG) prevents impedance increases in vitro, and reduces the percent change in impedance in vivo following implantation.Our results highlight the importance of considering the contributions of non-cellular components to the decline in neural microelectrode performance, and present a proof of concept for using a simple dip-coated PEG film to modulate changes in microelectrode impedance.

View Article: PubMed Central - PubMed

Affiliation: Weldon School of Biomedical Engineering, Purdue University West Lafayette, IN, USA ; Physiological Sensing Facility at the Bindley Bioscience Center and Birck Nanotechnology Center, Purdue University West Lafayette, IN, USA.

ABSTRACT
The reactive response of brain tissue to implantable intracortical microelectrodes is thought to negatively affect their recordable signal quality and impedance, resulting in unreliable longitudinal performance. The relationship between the progression of the reactive tissue into a glial scar and the decline in device performance is unclear. We show that exposure to a model protein solution in vitro and acute implantation result in both resistive and capacitive changes to electrode impedance, rather than purely resistive changes. We also show that applying 4000 MW polyethylene glycol (PEG) prevents impedance increases in vitro, and reduces the percent change in impedance in vivo following implantation. Our results highlight the importance of considering the contributions of non-cellular components to the decline in neural microelectrode performance, and present a proof of concept for using a simple dip-coated PEG film to modulate changes in microelectrode impedance.

No MeSH data available.


Related in: MedlinePlus

In vivo increase in resistance (A), reactance (B), and total impedance (C) from in vitro baseline, with and without PEG treatment. For either treatment condition, a significant increase in impedance (both resistance and reactance) from the in vitro baseline is observed at all frequencies (p < 0.05). For electrodes with no treatment, the percent increase in impedance (both resistance and reactance) from baseline was significantly higher (p < 0.05) than the percent increase with PEG treatment at all frequencies.
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Figure 4: In vivo increase in resistance (A), reactance (B), and total impedance (C) from in vitro baseline, with and without PEG treatment. For either treatment condition, a significant increase in impedance (both resistance and reactance) from the in vitro baseline is observed at all frequencies (p < 0.05). For electrodes with no treatment, the percent increase in impedance (both resistance and reactance) from baseline was significantly higher (p < 0.05) than the percent increase with PEG treatment at all frequencies.

Mentions: Figure 4A shows the percent increase of the real component of the impedance, i.e., resistance, between the in vitro baseline and the in vivo measurement at four frequency values across the spectrum. In both cases of no treatment and PEG treatment, the resistance exhibited a significant increase when measured in vivo compared to the in vitro baseline. Insertion into the cortex without PEG treatment, however, resulted in a larger increase from the in vitro baseline at all frequencies compared to insertion with PEG treatment. The percent change in resistance was also frequency-dependent. For the no treatment condition, the percent increase from baseline was as follows: 71.8 ± 2.99% at 50 Hz, 89.8 ± 3.77% at 100 Hz, 209.5 ± 9.1% at 1 kHz, and 290.5 ± 13.7% at 10 kHz; while for the PEG treatment condition, the percent increase from baseline was: 44.6 ± 3% at 50 Hz, 58 ± 3.9% at 100 Hz, 149.5 ± 9.3% at 1 kHz, and 223.3 ± 14% at 10 kHz. The percent increase in resistance from baseline for the no treatment condition was significantly different from the percent increase in resistance from baseline for the PEG treatment at all frequencies.


Resistive and reactive changes to the impedance of intracortical microelectrodes can be mitigated with polyethylene glycol under acute in vitro and in vivo settings.

Sommakia S, Gaire J, Rickus JL, Otto KJ - Front Neuroeng (2014)

In vivo increase in resistance (A), reactance (B), and total impedance (C) from in vitro baseline, with and without PEG treatment. For either treatment condition, a significant increase in impedance (both resistance and reactance) from the in vitro baseline is observed at all frequencies (p < 0.05). For electrodes with no treatment, the percent increase in impedance (both resistance and reactance) from baseline was significantly higher (p < 0.05) than the percent increase with PEG treatment at all frequencies.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4120760&req=5

Figure 4: In vivo increase in resistance (A), reactance (B), and total impedance (C) from in vitro baseline, with and without PEG treatment. For either treatment condition, a significant increase in impedance (both resistance and reactance) from the in vitro baseline is observed at all frequencies (p < 0.05). For electrodes with no treatment, the percent increase in impedance (both resistance and reactance) from baseline was significantly higher (p < 0.05) than the percent increase with PEG treatment at all frequencies.
Mentions: Figure 4A shows the percent increase of the real component of the impedance, i.e., resistance, between the in vitro baseline and the in vivo measurement at four frequency values across the spectrum. In both cases of no treatment and PEG treatment, the resistance exhibited a significant increase when measured in vivo compared to the in vitro baseline. Insertion into the cortex without PEG treatment, however, resulted in a larger increase from the in vitro baseline at all frequencies compared to insertion with PEG treatment. The percent change in resistance was also frequency-dependent. For the no treatment condition, the percent increase from baseline was as follows: 71.8 ± 2.99% at 50 Hz, 89.8 ± 3.77% at 100 Hz, 209.5 ± 9.1% at 1 kHz, and 290.5 ± 13.7% at 10 kHz; while for the PEG treatment condition, the percent increase from baseline was: 44.6 ± 3% at 50 Hz, 58 ± 3.9% at 100 Hz, 149.5 ± 9.3% at 1 kHz, and 223.3 ± 14% at 10 kHz. The percent increase in resistance from baseline for the no treatment condition was significantly different from the percent increase in resistance from baseline for the PEG treatment at all frequencies.

Bottom Line: We show that exposure to a model protein solution in vitro and acute implantation result in both resistive and capacitive changes to electrode impedance, rather than purely resistive changes.We also show that applying 4000 MW polyethylene glycol (PEG) prevents impedance increases in vitro, and reduces the percent change in impedance in vivo following implantation.Our results highlight the importance of considering the contributions of non-cellular components to the decline in neural microelectrode performance, and present a proof of concept for using a simple dip-coated PEG film to modulate changes in microelectrode impedance.

View Article: PubMed Central - PubMed

Affiliation: Weldon School of Biomedical Engineering, Purdue University West Lafayette, IN, USA ; Physiological Sensing Facility at the Bindley Bioscience Center and Birck Nanotechnology Center, Purdue University West Lafayette, IN, USA.

ABSTRACT
The reactive response of brain tissue to implantable intracortical microelectrodes is thought to negatively affect their recordable signal quality and impedance, resulting in unreliable longitudinal performance. The relationship between the progression of the reactive tissue into a glial scar and the decline in device performance is unclear. We show that exposure to a model protein solution in vitro and acute implantation result in both resistive and capacitive changes to electrode impedance, rather than purely resistive changes. We also show that applying 4000 MW polyethylene glycol (PEG) prevents impedance increases in vitro, and reduces the percent change in impedance in vivo following implantation. Our results highlight the importance of considering the contributions of non-cellular components to the decline in neural microelectrode performance, and present a proof of concept for using a simple dip-coated PEG film to modulate changes in microelectrode impedance.

No MeSH data available.


Related in: MedlinePlus