Glassy Carbon Microelectrodes for High Charge Injection, High Stability and Low Noise Neural Interfaces
Event details
| Date | 20.10.2016 |
| Hour | 10:00 › 11:00 |
| Speaker | Prof. Sam Kassegne, San Diego State University, CA, USA. |
| Location | |
| Category | Conferences - Seminars |
For neural applications, materials that are capable of interfacing with the brain and spinal cord without harming them while recording high-fidelity signals over long-term are still sought after. In this talk, we report on a new electrode material fabricated from lithographically patterned glassy carbon (GC) that promises to achieve this by combining superior electrochemical properties for neural recordings and better long-term stability under electrical stimulation than current thin film metal microelectrodes. We demonstrate that lithographically patterned glassy carbon microelectrodes can withstand at least 5 million pulses at 0.45mC/cm2 charge density with <7.5% impedance change, have >70% wider electrochemical window and 70% higher CTC (charge transfer capacity) than platinum (Pt) microelectrodes of similar geometry, which delaminated after 1 million pulses. For direct comparisons, ultra-flexible, micro-electrocorticography (μ-ECoG) arrays with GC electrodes were manufactured using recently introduced pattern transfer techniques, while thin-film platinum arrays were fabricated using conventional microfabrication methods. Additionally, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) was selectively electrodeposited on both sets of devices to specifically reduce their impedances for smaller diameters (<60μm). We observed that PEDOT-PSS adhered significantly better to GC than Pt, presumably due to stronger interaction between GC and carbonaceous PSS-PEDOT chains, and allowed drastic reduction of electrode size while maintaining same amount of delivered current. Further, acute in-vivo characterization was performed in rats and it is shown that GC microelectrode arrays recorded somatosensory evoked potentials (SEP) with an almost twice SNR (signal-to-noise ratio) when compared to the Pt ones. Supported by characterizations and computational modeling results, the talk will demonstrate (i) the reason behind long-term corrosion problems in thin-film metal microelectrodes and the promise of homogenous electrode material such as GC and (ii) the microenvironment and response of tissues to long-term electrical stimulations. In this talk, we will also introduce some of the key research activities being carried out at CSNE (Center for Sensorimotor and Neural Engineering), NSF-funded Engineering Research Center with University of Washington, MIT, and San Diego State University (SDSU) as leading institutions.
Practical information
- Informed public
- Free
Organizer
- Bertarelli Foundation Chair in Translational Neuroengineering - Center for Neuroprosthetics