Soft, Conductive, Brain-Like, Coatings at Tips of Microelectrodes Improve Electrical Stability under Chronic, In Vivo Conditions
Several recent studies have reported improved histological and electrophysiological outcomes with soft neural interfaces that have elastic moduli ranging from 10 s of kPa to hundreds of MPa. However, many of these soft interfaces use custom fabrication processes. We test the hypothesis that a readil...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-06-01
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| Series: | Micromachines |
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| Online Access: | https://www.mdpi.com/2072-666X/12/7/761 |
| _version_ | 1797528561901371392 |
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| author | Arati Sridharan Jit Muthuswamy |
| author_facet | Arati Sridharan Jit Muthuswamy |
| author_sort | Arati Sridharan |
| collection | DOAJ |
| description | Several recent studies have reported improved histological and electrophysiological outcomes with soft neural interfaces that have elastic moduli ranging from 10 s of kPa to hundreds of MPa. However, many of these soft interfaces use custom fabrication processes. We test the hypothesis that a readily adoptable fabrication process for only coating the tips of microelectrodes with soft brain-like (elastic modulus of ~5 kPa) material improves the long-term electrical performance of neural interfaces. Conventional tungsten microelectrodes (<i>n</i> = 9 with soft coatings and <i>n</i> = 6 uncoated controls) and Pt/Ir microelectrodes (<i>n</i> = 16 with soft coatings) were implanted in six animals for durations ranging from 5 weeks to over 1 year in a subset of rats. Electrochemical impedance spectroscopy was used to assess the quality of the brain tissue–electrode interface under chronic conditions. Neural recordings were assessed for unit activity and signal quality. Electrodes with soft, silicone coatings showed relatively stable electrical impedance characteristics over 6 weeks to >1 year compared to the uncoated control electrodes. Single unit activity recorded by coated electrodes showed larger peak-to-peak amplitudes and increased number of detectable neurons compared to uncoated controls over 6–7 weeks. We demonstrate the feasibility of using a readily translatable process to create brain-like soft interfaces that can potentially overcome variable performance associated with chronic rigid neural interfaces. |
| first_indexed | 2024-03-10T10:00:06Z |
| format | Article |
| id | doaj.art-df26b03a28c34af8b799ad91c0aabedf |
| institution | Directory Open Access Journal |
| issn | 2072-666X |
| language | English |
| last_indexed | 2024-03-10T10:00:06Z |
| publishDate | 2021-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Micromachines |
| spelling | doaj.art-df26b03a28c34af8b799ad91c0aabedf2023-11-22T02:00:49ZengMDPI AGMicromachines2072-666X2021-06-0112776110.3390/mi12070761Soft, Conductive, Brain-Like, Coatings at Tips of Microelectrodes Improve Electrical Stability under Chronic, In Vivo ConditionsArati Sridharan0Jit Muthuswamy1School of Biological and Health Systems Engineering, Ira A. Fulton School of Engineering, Arizona State University, Tempe, AZ 85287-9709, USASchool of Biological and Health Systems Engineering, Ira A. Fulton School of Engineering, Arizona State University, Tempe, AZ 85287-9709, USASeveral recent studies have reported improved histological and electrophysiological outcomes with soft neural interfaces that have elastic moduli ranging from 10 s of kPa to hundreds of MPa. However, many of these soft interfaces use custom fabrication processes. We test the hypothesis that a readily adoptable fabrication process for only coating the tips of microelectrodes with soft brain-like (elastic modulus of ~5 kPa) material improves the long-term electrical performance of neural interfaces. Conventional tungsten microelectrodes (<i>n</i> = 9 with soft coatings and <i>n</i> = 6 uncoated controls) and Pt/Ir microelectrodes (<i>n</i> = 16 with soft coatings) were implanted in six animals for durations ranging from 5 weeks to over 1 year in a subset of rats. Electrochemical impedance spectroscopy was used to assess the quality of the brain tissue–electrode interface under chronic conditions. Neural recordings were assessed for unit activity and signal quality. Electrodes with soft, silicone coatings showed relatively stable electrical impedance characteristics over 6 weeks to >1 year compared to the uncoated control electrodes. Single unit activity recorded by coated electrodes showed larger peak-to-peak amplitudes and increased number of detectable neurons compared to uncoated controls over 6–7 weeks. We demonstrate the feasibility of using a readily translatable process to create brain-like soft interfaces that can potentially overcome variable performance associated with chronic rigid neural interfaces.https://www.mdpi.com/2072-666X/12/7/761brain implantsneural prosthesesPDMSsiliconechronic implants |
| spellingShingle | Arati Sridharan Jit Muthuswamy Soft, Conductive, Brain-Like, Coatings at Tips of Microelectrodes Improve Electrical Stability under Chronic, In Vivo Conditions Micromachines brain implants neural prostheses PDMS silicone chronic implants |
| title | Soft, Conductive, Brain-Like, Coatings at Tips of Microelectrodes Improve Electrical Stability under Chronic, In Vivo Conditions |
| title_full | Soft, Conductive, Brain-Like, Coatings at Tips of Microelectrodes Improve Electrical Stability under Chronic, In Vivo Conditions |
| title_fullStr | Soft, Conductive, Brain-Like, Coatings at Tips of Microelectrodes Improve Electrical Stability under Chronic, In Vivo Conditions |
| title_full_unstemmed | Soft, Conductive, Brain-Like, Coatings at Tips of Microelectrodes Improve Electrical Stability under Chronic, In Vivo Conditions |
| title_short | Soft, Conductive, Brain-Like, Coatings at Tips of Microelectrodes Improve Electrical Stability under Chronic, In Vivo Conditions |
| title_sort | soft conductive brain like coatings at tips of microelectrodes improve electrical stability under chronic in vivo conditions |
| topic | brain implants neural prostheses PDMS silicone chronic implants |
| url | https://www.mdpi.com/2072-666X/12/7/761 |
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