Abstract Objective: Flexible Electrocorticography (ECoG) electrode arrays that conform to the cortical surface and record surface field potentials from multiple brain regions provide unique insights into how computations occurring in distributed brain regions mediate behavior. Specialized microfabrication methods are required to produce flexible ECoG devices with high-density electrode arrays. However, these fabrication methods are challenging for scientists without access to cleanroom fabrication equipment. Results: Here we present a fully desktop fabricated flexible graphene ECoG array. First, we synthesized a stable, conductive ink via liquid exfoliation of Graphene in Cyrene. Next, we established a stencil-printing process for patterning the graphene ink via laser-cut stencils on flexible polyimide substrates. Benchtop tests indicate that the graphene electrodes have good conductivity of ∼1.1 × 10 3 S cm −1 , flexibility to maintain their electrical connection under static bending, and electrochemical stability in a 15 d accelerated corrosion test. Chronically implanted graphene ECoG devices remain fully functional for up to 180 d, with average in vivo impedances of 24.72 ± 95.23 kΩ at 1 kHz. The ECoG device can measure spontaneous surface field potentials from mice under awake and anesthetized states and sensory stimulus-evoked responses. Significance: The stencil-printing fabrication process can be used tomore »
On-Wafer Graphene Devices for THz Applications Using a High-Yield Fabrication Process
We characterize a novel fabrication procedure for the implementation of large arrays of subwavelength graphene devices. With the proposed process, we can now integrate graphene layers on large substrate areas (> 4 cm2) and implement thousands of devices with high-yield (> 90 %). Examples of such systems include broadband THz phased arrays and metasurfaces that can be used in THz imaging and sensing. Current nano-fabrication processes hinder the proliferation of large arrays due to the fragile nature of graphene. Conversely, we use titanium sacrificial layers to protect the delicate graphene throughout the fabrication process. Thus, we minimize graphene delamination and enable multiple devices on large-area substrates with high-yield. In addition, we present a series of on-wafer measurement results in the 220-330 GHz band, verifying the robustness of our fabrication process.
- Award ID(s):
- 1847138
- Publication Date:
- NSF-PAR ID:
- 10135990
- Journal Name:
- 2019 IEEE MTT-S International Microwave Symposium (IMS)
- Page Range or eLocation-ID:
- 1107 to 1110
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.1109/MWSYM.2019.8701093
