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Event Details

  • Monday, February 25, 2019
  • 15:30 - 16:00

Carbon and the Future of Multi-Modal Neural Interfaces

Carbon is fast becoming a leading material of choice in micro and nanofabrication of a variety of sensors, actuators, microelectrodes, wires, batteries, fuel cells, thin-films, and neural interfaces. Its unique tunable mechanical and electronic properties enabled by the availability of a range of possible hybridized bonds (sp2 and sp3) make it a versatile material. Further, carbon has a potential to assume even more far-reaching importance with discovery of newer carbon forms and allotropes such as graphene (excellent conductivity and strength), patternable glassy carbon (excellent electrochemistry), Q-carbon (excellent hardness) and compressed glassy carbon (excellent strength). Research progress in devices that interface with the human body, particularly with the CNS (central nervous system) and PNS (peripheral nervous system) continues, with two key application areas, i.e., (i) BCI (cortical and spinal neuroprosthetics) and (ii) bioelectronics (treating chronic conditions through electrical stimulation of vagus nerves, emerging as promising areas for clinical translation. Against this background, carbon’s excellent conductivity, robust electrochemical activity as well as homogenous microstructure offer a very more compelling in-vivo platform for multi-modal neural interfaces for extended period of implantation. In this talk, therefore, we report a new class of carbon-based neural probes that consist of homogeneous glassy carbon (GC) microelectrodes, interconnects and bump pads with superior electrochemical properties, in-vivo performance and long-term stability under electrical stimulation. These electrodes have purely capacitive behavior with exceptionally high charge storage capacity (CSC) and are capable of sustaining more than 3.5 billion cycles of bi-phasic pulses at charge density of 0.25 mC/cm2. Extensive in-vivo and in-vitro tests confirmed: (i) high SNR (>16) recordings, (ii) highest reported CSC for non-coated neural probe (61.4± 6.9 mC/cm2), (iii) high-resolution dopamine detection (10 nM level - one of the lowest reported so far), (iv) recording of both electrical and electrochemical signals, and (v) no failure after 3.5 billion cycles of pulses. 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.