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Improving impedance of implantable microwire multi-electrode arrays by ultrasonic electroplating of durable platinum black.

Desai SA, Rolston JD, Guo L, Potter SM - Front Neuroeng (2010)

Bottom Line: However, because of the low durability of Pt black plating, this method has not been popular for chronic use.Sonicoplating (i.e. electroplating under ultrasonic agitation) has been shown to improve the durability of Pt black on the base metals of macro-electrodes used for cyclic voltammetry.We show here that sonicoplating can lower the impedances of microwire multi-electrode arrays (MMEA) by an order of magnitude or more (depending on the time and voltage of electroplating), with better durability compared to pulsed plating or traditional DC methods.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Neuroengineering, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology Atlanta, GA, USA.

ABSTRACT
Implantable microelectrode arrays (MEAs) have been a boon for neural stimulation and recording experiments. Commercially available MEAs have high impedances, due to their low surface area and small tip diameters, which are suitable for recording single unit activity. Lowering the electrode impedance, but preserving the small diameter, would provide a number of advantages, including reduced stimulation voltages, reduced stimulation artifacts and improved signal-to-noise ratio. Impedance reductions can be achieved by electroplating the MEAs with platinum (Pt) black, which increases the surface area but has little effect on the physical extent of the electrodes. However, because of the low durability of Pt black plating, this method has not been popular for chronic use. Sonicoplating (i.e. electroplating under ultrasonic agitation) has been shown to improve the durability of Pt black on the base metals of macro-electrodes used for cyclic voltammetry. This method has not previously been characterized for MEAs used in chronic neural implants. We show here that sonicoplating can lower the impedances of microwire multi-electrode arrays (MMEA) by an order of magnitude or more (depending on the time and voltage of electroplating), with better durability compared to pulsed plating or traditional DC methods. We also show the improved stimulation and recording performance that can be achieved in an in vivo implantation study with the sonicoplated low-impedance MMEAs, compared to high-impedance unplated electrodes.

No MeSH data available.


Related in: MedlinePlus

Thermal noise and EMI together contribute less than 10% of the total noise in an in vivo recording (A) A 17 min recording from a rat on an unplated electrode showing the cessation of neural activity after an injection of euthasol. (B) (L–R) recording on an unplated, sonicoplated, pulsed plated and DC plated electrode in a euthanized rat. Mean RMS noise levels on the three types of plated and unplated electrodes are shown below the respective plots. No significant difference (0.3 < p < 0.6) is seen in the noise levels on the three types of plated and unplated electrodes.
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Figure 9: Thermal noise and EMI together contribute less than 10% of the total noise in an in vivo recording (A) A 17 min recording from a rat on an unplated electrode showing the cessation of neural activity after an injection of euthasol. (B) (L–R) recording on an unplated, sonicoplated, pulsed plated and DC plated electrode in a euthanized rat. Mean RMS noise levels on the three types of plated and unplated electrodes are shown below the respective plots. No significant difference (0.3 < p < 0.6) is seen in the noise levels on the three types of plated and unplated electrodes.

Mentions: A continuous recording was made before and after a lethal dose of euthasol. Figure 9A shows brain activity ceasing ∼13 min post injection. At this time, the total noise recorded on the same unplated electrode had an RMS amplitude of about 9 μV. Because brain activity ceases within 13 min after circulation ceases, it can be safely assumed that most of the 9 μV noise observed is thermal noise and noise due to electromagnetic interference (EMI).


Improving impedance of implantable microwire multi-electrode arrays by ultrasonic electroplating of durable platinum black.

Desai SA, Rolston JD, Guo L, Potter SM - Front Neuroeng (2010)

Thermal noise and EMI together contribute less than 10% of the total noise in an in vivo recording (A) A 17 min recording from a rat on an unplated electrode showing the cessation of neural activity after an injection of euthasol. (B) (L–R) recording on an unplated, sonicoplated, pulsed plated and DC plated electrode in a euthanized rat. Mean RMS noise levels on the three types of plated and unplated electrodes are shown below the respective plots. No significant difference (0.3 < p < 0.6) is seen in the noise levels on the three types of plated and unplated electrodes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2871717&req=5

Figure 9: Thermal noise and EMI together contribute less than 10% of the total noise in an in vivo recording (A) A 17 min recording from a rat on an unplated electrode showing the cessation of neural activity after an injection of euthasol. (B) (L–R) recording on an unplated, sonicoplated, pulsed plated and DC plated electrode in a euthanized rat. Mean RMS noise levels on the three types of plated and unplated electrodes are shown below the respective plots. No significant difference (0.3 < p < 0.6) is seen in the noise levels on the three types of plated and unplated electrodes.
Mentions: A continuous recording was made before and after a lethal dose of euthasol. Figure 9A shows brain activity ceasing ∼13 min post injection. At this time, the total noise recorded on the same unplated electrode had an RMS amplitude of about 9 μV. Because brain activity ceases within 13 min after circulation ceases, it can be safely assumed that most of the 9 μV noise observed is thermal noise and noise due to electromagnetic interference (EMI).

Bottom Line: However, because of the low durability of Pt black plating, this method has not been popular for chronic use.Sonicoplating (i.e. electroplating under ultrasonic agitation) has been shown to improve the durability of Pt black on the base metals of macro-electrodes used for cyclic voltammetry.We show here that sonicoplating can lower the impedances of microwire multi-electrode arrays (MMEA) by an order of magnitude or more (depending on the time and voltage of electroplating), with better durability compared to pulsed plating or traditional DC methods.

View Article: PubMed Central - PubMed

Affiliation: Laboratory for Neuroengineering, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology Atlanta, GA, USA.

ABSTRACT
Implantable microelectrode arrays (MEAs) have been a boon for neural stimulation and recording experiments. Commercially available MEAs have high impedances, due to their low surface area and small tip diameters, which are suitable for recording single unit activity. Lowering the electrode impedance, but preserving the small diameter, would provide a number of advantages, including reduced stimulation voltages, reduced stimulation artifacts and improved signal-to-noise ratio. Impedance reductions can be achieved by electroplating the MEAs with platinum (Pt) black, which increases the surface area but has little effect on the physical extent of the electrodes. However, because of the low durability of Pt black plating, this method has not been popular for chronic use. Sonicoplating (i.e. electroplating under ultrasonic agitation) has been shown to improve the durability of Pt black on the base metals of macro-electrodes used for cyclic voltammetry. This method has not previously been characterized for MEAs used in chronic neural implants. We show here that sonicoplating can lower the impedances of microwire multi-electrode arrays (MMEA) by an order of magnitude or more (depending on the time and voltage of electroplating), with better durability compared to pulsed plating or traditional DC methods. We also show the improved stimulation and recording performance that can be achieved in an in vivo implantation study with the sonicoplated low-impedance MMEAs, compared to high-impedance unplated electrodes.

No MeSH data available.


Related in: MedlinePlus