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pHEMA Encapsulated PEDOT-PSS-CNT Microsphere Microelectrodes for Recording Single Unit Activity in the Brain.

Castagnola E, Maggiolini E, Ceseracciu L, Ciarpella F, Zucchini E, De Faveri S, Fadiga L, Ricci D - Front Neurosci (2016)

Bottom Line: This enhancement significantly reduces the size of the implantable device though preserving excellent electrical performances.Moreover, the spherical shape of the electrode together with the surface area increase provided by the nanocomposite deposited on it, maximize the electrical contact and may improve recording stability over time.These results have a good potential to contribute to fulfill the grand challenge of obtaining stable neural interfaces for long-term applications.

View Article: PubMed Central - PubMed

Affiliation: Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia Ferrara, Italy.

ABSTRACT
The long-term reliability of neural interfaces and stability of high-quality recordings are still unsolved issues in neuroscience research. High surface area PEDOT-PSS-CNT composites are able to greatly improve the performance of recording and stimulation for traditional intracortical metal microelectrodes by decreasing their impedance and increasing their charge transfer capability. This enhancement significantly reduces the size of the implantable device though preserving excellent electrical performances. On the other hand, the presence of nanomaterials often rises concerns regarding possible health hazards, especially when considering a clinical application of the devices. For this reason, we decided to explore the problem from a new perspective by designing and testing an innovative device based on nanostructured microspheres grown on a thin tether, integrating PEDOT-PSS-CNT nanocomposites with a soft synthetic permanent biocompatible hydrogel. The pHEMA hydrogel preserves the electrochemical performance and high quality recording ability of PEDOT-PSS-CNT coated devices, reduces the mechanical mismatch between soft brain tissue and stiff devices and also avoids direct contact between the neural tissue and the nanocomposite, by acting as a biocompatible protective barrier against potential nanomaterial detachment. Moreover, the spherical shape of the electrode together with the surface area increase provided by the nanocomposite deposited on it, maximize the electrical contact and may improve recording stability over time. These results have a good potential to contribute to fulfill the grand challenge of obtaining stable neural interfaces for long-term applications.

No MeSH data available.


Related in: MedlinePlus

(A) Impedance spectra of commercial microelectrodes (black), gold microspheres before (blue) and after (red) PEDOT-PSS-CNT electrodeposition and (green) PEDOT-PSS-CNT coated microspheres after pHEMA encapsulation. (B) Sample cyclic voltammograms of a gold microsphere (blue) and a PEDOT-PSS-CNT coated microsphere before (green) and after (red) pHEMA encapsulation.
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Figure 1: (A) Impedance spectra of commercial microelectrodes (black), gold microspheres before (blue) and after (red) PEDOT-PSS-CNT electrodeposition and (green) PEDOT-PSS-CNT coated microspheres after pHEMA encapsulation. (B) Sample cyclic voltammograms of a gold microsphere (blue) and a PEDOT-PSS-CNT coated microsphere before (green) and after (red) pHEMA encapsulation.

Mentions: Coating the gold microspheres, that had a diameter in the range of 100 μm (106.5 ± 9.3 μm, N = 10) with PEDOT-PSS-CNT significantly reduces their impedance, as shown by the impedance spectra reported in Figure 1A. The impedance values of pristine gold microspheres are 3.96 ± 0.95 kΩ at 1 kHz, 13.04 ± 3.07 kΩ at 100 Hz and 324.04 ± 100.37 kΩ at 1 Hz (mean ± standard deviation, 10 samples), much lower than commercially available intracortical microelectrodes, i.e., quartz insulated platinum/tungsten tips (Ansaldo et al., 2011). PEDOT-PSS-CNT coating further decreases the impedance in all the frequency range, and especially in the low frequency band (1.04 ± 0.17 kΩ at 1 kHz, 1.24 ± 0.24 at 100 Hz and 9.56 ± 4.13 at 1 Hz). A second effect of PEDOT-PSS-CNT coating is the large increase in charge transfer capability (CTC), calculated as the time integral of an entire CV cycle between 0.6 and −1V, that passes from 101.6 ± 64.4 mC/cm2 of the pristine gold microspheres to 540.7 ± 70.3 mC/cm2 of the PEDOT-PSS-CNT coated ones. An example of CVs of pristine and PEDOT-PSS-CNT coated microspheres is shown in Figure 1B.


pHEMA Encapsulated PEDOT-PSS-CNT Microsphere Microelectrodes for Recording Single Unit Activity in the Brain.

Castagnola E, Maggiolini E, Ceseracciu L, Ciarpella F, Zucchini E, De Faveri S, Fadiga L, Ricci D - Front Neurosci (2016)

(A) Impedance spectra of commercial microelectrodes (black), gold microspheres before (blue) and after (red) PEDOT-PSS-CNT electrodeposition and (green) PEDOT-PSS-CNT coated microspheres after pHEMA encapsulation. (B) Sample cyclic voltammograms of a gold microsphere (blue) and a PEDOT-PSS-CNT coated microsphere before (green) and after (red) pHEMA encapsulation.
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Related In: Results  -  Collection

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Figure 1: (A) Impedance spectra of commercial microelectrodes (black), gold microspheres before (blue) and after (red) PEDOT-PSS-CNT electrodeposition and (green) PEDOT-PSS-CNT coated microspheres after pHEMA encapsulation. (B) Sample cyclic voltammograms of a gold microsphere (blue) and a PEDOT-PSS-CNT coated microsphere before (green) and after (red) pHEMA encapsulation.
Mentions: Coating the gold microspheres, that had a diameter in the range of 100 μm (106.5 ± 9.3 μm, N = 10) with PEDOT-PSS-CNT significantly reduces their impedance, as shown by the impedance spectra reported in Figure 1A. The impedance values of pristine gold microspheres are 3.96 ± 0.95 kΩ at 1 kHz, 13.04 ± 3.07 kΩ at 100 Hz and 324.04 ± 100.37 kΩ at 1 Hz (mean ± standard deviation, 10 samples), much lower than commercially available intracortical microelectrodes, i.e., quartz insulated platinum/tungsten tips (Ansaldo et al., 2011). PEDOT-PSS-CNT coating further decreases the impedance in all the frequency range, and especially in the low frequency band (1.04 ± 0.17 kΩ at 1 kHz, 1.24 ± 0.24 at 100 Hz and 9.56 ± 4.13 at 1 Hz). A second effect of PEDOT-PSS-CNT coating is the large increase in charge transfer capability (CTC), calculated as the time integral of an entire CV cycle between 0.6 and −1V, that passes from 101.6 ± 64.4 mC/cm2 of the pristine gold microspheres to 540.7 ± 70.3 mC/cm2 of the PEDOT-PSS-CNT coated ones. An example of CVs of pristine and PEDOT-PSS-CNT coated microspheres is shown in Figure 1B.

Bottom Line: This enhancement significantly reduces the size of the implantable device though preserving excellent electrical performances.Moreover, the spherical shape of the electrode together with the surface area increase provided by the nanocomposite deposited on it, maximize the electrical contact and may improve recording stability over time.These results have a good potential to contribute to fulfill the grand challenge of obtaining stable neural interfaces for long-term applications.

View Article: PubMed Central - PubMed

Affiliation: Center for Translational Neurophysiology of Speech and Communication, Istituto Italiano di Tecnologia Ferrara, Italy.

ABSTRACT
The long-term reliability of neural interfaces and stability of high-quality recordings are still unsolved issues in neuroscience research. High surface area PEDOT-PSS-CNT composites are able to greatly improve the performance of recording and stimulation for traditional intracortical metal microelectrodes by decreasing their impedance and increasing their charge transfer capability. This enhancement significantly reduces the size of the implantable device though preserving excellent electrical performances. On the other hand, the presence of nanomaterials often rises concerns regarding possible health hazards, especially when considering a clinical application of the devices. For this reason, we decided to explore the problem from a new perspective by designing and testing an innovative device based on nanostructured microspheres grown on a thin tether, integrating PEDOT-PSS-CNT nanocomposites with a soft synthetic permanent biocompatible hydrogel. The pHEMA hydrogel preserves the electrochemical performance and high quality recording ability of PEDOT-PSS-CNT coated devices, reduces the mechanical mismatch between soft brain tissue and stiff devices and also avoids direct contact between the neural tissue and the nanocomposite, by acting as a biocompatible protective barrier against potential nanomaterial detachment. Moreover, the spherical shape of the electrode together with the surface area increase provided by the nanocomposite deposited on it, maximize the electrical contact and may improve recording stability over time. These results have a good potential to contribute to fulfill the grand challenge of obtaining stable neural interfaces for long-term applications.

No MeSH data available.


Related in: MedlinePlus