(Invited) Laser-Induced Graphene on Polymers: From Process Science to Applications

Abstract

Nanocarbons like graphene and carbon nanotubes (CNTs) are promising for various applications including advanced electronic devices, novel energy systems, and next-generation healthcare diagnostics. This is owing to the excellent physical, chemical and electrochemical properties arising from the ordered atomic structure, the hierarchical nanoscale morphology, and tunable chemistry of nanocarbons. In particular, low-dimensional carbon electrodes for biosensors and neural interfaces have consistently been shown to have superior performance when compared to state-of-the-art metal electrodes. Nevertheless, major manufacturing challenges still hinder our ability to scalably produce graphene-based electrodes with tailored morphology and surface chemistry, especially on flexible substrates. While chemical vapor deposition (CVD) processes enable the synthesis of high quality graphene and CNTs, the extreme environments of high temperatures and hydrocarbon-rich gaseous atmosphere in such reactors limit the choice of substrates to silicon, quartz, metals or other rigid temperature-resistant materials. On the other hand, many emerging flexible devices require the fabrication of such nanocarbon electrodes on the surface of polymer substrates. Unlike different transfer technique of CVD-grown nanocarbons, this talk will focus on a unique bottom-up approach for directly growing different types of graphenic nanocarbons on polymer films by laser irradiation. The speaker will show how this direct-write process, often referred to as laser-induced graphene (LIG), can be controlled to produce spatially-varying morphologies and chemical compositions of LIG electrodes, by leveraging gradients of laser fluence. Moreover, a method will be introduced to control the heteroatom doping of these LIG electrodes based on controlling the molecular structure of the polymer being lased. Finally, a demonstration of these functional LIG electrodes as electrochemical biosensors will be presented for the detection of the neurotransmitter dopamine with nanomolar sensitivity.