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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.


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Representative SEM images of (A) PEDOT-PSS-CNT coated microsphere (without pHEMA) and (B) pHEMA encapsulated PEDOT-PSS-CNT coated microsphere after 28 days of permanence in rat brain.
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Figure 12: Representative SEM images of (A) PEDOT-PSS-CNT coated microsphere (without pHEMA) and (B) pHEMA encapsulated PEDOT-PSS-CNT coated microsphere after 28 days of permanence in rat brain.

Mentions: The impedance spectra behavior in the whole frequency range (1 ÷ 105 Hz), reported in Table 4, is similar for both types of microelectrodes, with an increase of impedance after the first day from the implant. The impedance spectra respectively of non-encapsulated and pHEMA-encapsulated PEDOT-PSS-CNT 1, 7, 14, 21, and 28 days microspheres from the implant are shown in Figure 8. These impedance values stay within the impedance range that allows to efficiently record action potentials during the whole implant period, as previously shown (Figures 6, 7). The implanted microspheres, after being removed from the brain, were analyzed using SEM. This confirmed the persistence of an intact pHEMA encapsulation and no insulation delamination. Figures 12A,B shows some examples of high-magnification SEM images of the surface for non-encapsulated and pHEMA encapsulated PEDOT-PSS-CNT microspheres, respectively, after 28 days from the implant. The PEDOT-PSS-CNT exhibits its typical rough and porous morphology, while the pHEMA encapsulation maintains its smooth surface morphology. When EDS analysis (see Section Sturdiness and Electrochemical Stability of pHEMA Encapsulation and Table 2) was performed on these samples, we found results similar to those obtained on pristine samples, indicating that the pHEMA encapsulation withstands brain insertion and 28 days implant.


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)

Representative SEM images of (A) PEDOT-PSS-CNT coated microsphere (without pHEMA) and (B) pHEMA encapsulated PEDOT-PSS-CNT coated microsphere after 28 days of permanence in rat brain.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834343&req=5

Figure 12: Representative SEM images of (A) PEDOT-PSS-CNT coated microsphere (without pHEMA) and (B) pHEMA encapsulated PEDOT-PSS-CNT coated microsphere after 28 days of permanence in rat brain.
Mentions: The impedance spectra behavior in the whole frequency range (1 ÷ 105 Hz), reported in Table 4, is similar for both types of microelectrodes, with an increase of impedance after the first day from the implant. The impedance spectra respectively of non-encapsulated and pHEMA-encapsulated PEDOT-PSS-CNT 1, 7, 14, 21, and 28 days microspheres from the implant are shown in Figure 8. These impedance values stay within the impedance range that allows to efficiently record action potentials during the whole implant period, as previously shown (Figures 6, 7). The implanted microspheres, after being removed from the brain, were analyzed using SEM. This confirmed the persistence of an intact pHEMA encapsulation and no insulation delamination. Figures 12A,B shows some examples of high-magnification SEM images of the surface for non-encapsulated and pHEMA encapsulated PEDOT-PSS-CNT microspheres, respectively, after 28 days from the implant. The PEDOT-PSS-CNT exhibits its typical rough and porous morphology, while the pHEMA encapsulation maintains its smooth surface morphology. When EDS analysis (see Section Sturdiness and Electrochemical Stability of pHEMA Encapsulation and Table 2) was performed on these samples, we found results similar to those obtained on pristine samples, indicating that the pHEMA encapsulation withstands brain insertion and 28 days implant.

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