Frontiers of Materials Award Symposium: Nanocarbon-based Flexible Devices: Emerging Materials and Processes: Session III: Emerging Nanocarbon Applications
Program Organizers: Mostafa Bedewy, University of Pittsburgh
Tuesday 8:00 AM
March 1, 2022
Room: 260A
Location: Anaheim Convention Center
8:00 AM Introductory Comments
8:05 AM Invited
Probing the Brain with Carbon Microelectrode Arrays: Promises and Challenges: Elisa Castagnola1; 1University of Pittsburgh
Carbon electrodes offer intriguing properties for neural-interface applications, such as biocompatibility, electrochemical stability, capacitive electrochemical behavior, and fast electron-transfer kinetics. Considered the ideal material for electrochemical detection, carbon has only recently been investigated as electrode material for electrophysiology recordings and micro-stimulation. The integration of carbon in implantable microelectrode arrays (MEAs) would enable the multimodal probing of the brain, elucidating the relationship between electrical and electrochemical signaling and the mechanisms that underpin the efficacy of electrical stimulation for neurotransmission and neuromodulation. This presentation provides an overview of the different strategies we recently adopted for the development of implantable carbon-based MEAs and reports the promising results we obtained in their neural interface applications, including neurochemical sensing and stimulation. Promises and challenges of the use of carbon in the next-generation of neural technology will be discussed.
8:35 AM Invited
Wafer-scale Processing of Carbon Nanotube Forests for High-performance, Flexible Composites: Eric Meshot1; 1Lawrence Livermore National Laboratory
We developed a fabrication workflow for advanced, flexible composites derived from vertically aligned single-walled carbon nanotube (SWCNT) “forests” based on a series of wafer-scale chemical vapor deposition (CVD) techniques. Our initial SWCNT synthesis co-optimized growth of small diameters (mean < 2 nm) and high densities (> 1012 cm-2) uniformly across large areas (6-in. wafers) to access new territory in this 3D parameter space. Mass conversion rates from low-pressure acetylene to solid SWCNT product were high (up to 65%) and remarkably invariant for different metal nano-catalyst compositions and densities, far exceeding typical benchtop reactors. Subsequent vapor-phase polymer chemistry enabled functionalization and infiltration within nanoscale voids between SWCNTs without destroying the unique aligned morphology. Routine manufacture of these high-quality materials at a practical scale unlocked a portfolio of high-performance applications, including optical metamaterials, twist-spun yarns, and nanofluidic devices for molecular separation, energy storage, and sensing.
9:05 AM Invited
Electromechanically Stable Thin Metallic Films Reinforced by Synthesis of a Graphene Wrapper: Sameh Tawfick1; Kaihao Zhang1; Mitisha Surana1; Jad Yaacoub1; 1University of Illinois at Urbana Champaign
Thin metallic films are important building blocks of electronic devices. However, their use in flexible electronic devices, even when patterned to create elastic compliance, is challenged by their brittle nature. In this work, we use ultrafast chemical vapor deposition recipes to synthesize graphene on palladium thin films in the range of 200-700 nm, where the thin films act as a catalyst for growth, and later as an electronic conductor for flexible electronics. First, we test the intrinsic stiffness, strength and fracture toughness of these graphene-wrapped films (PdGr) using a suspended-strip indentation approach and show an enhancement of 50-100% in these films. Secondly, we perform systematic mechanical behavior testing with in situ electrical resistivity measurement to quantify this enhancement of electrical performance stability. Finally, we perform fatigue mechanical testing on serpentine patterns embedded in elastomers and show simultaneous electromechanical stability enhancement. The enhancement mechanism is under investigation.
9:35 AM Invited
Controlled Deformation of Graphene for Flexible Electronics: SungWoo Nam1; 1University of California, Irvine
Many mechanical deformations, such as buckling, crumpling, wrinkling, and delamination, are usually considered as threats to mechanical integrity and are avoided or reduced in the traditional design of materials and structures. My work goes against these conventions by tailoring such mechanical instabilities to create new functional morphologies. In this talk, I will present our works on controlled deformation and interfacial control of van der Waals materials for flexible and deformable electronics. First, I will introduce our mechanical instability-driven nano-manufacturing approaches to induce controlled deformation of graphene. Furthermore, I will present our work on interfacial control using graphene to modulate fracture modes of thinfilms to enable a new phenomenon of ‘electrical ductility’. These mechanical instability-induced modulations of materials at the atomic level will open the door to new phases of matter with unconventional and reconfigurable properties for applications in next generation deformable electronics.