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Measurements of the gas sensing performance of nanomaterials typically involve the use of interdigitated electrodes (IDEs). A separate heater is often integrated to provide elevated temperature for improved sensing performance. However, the use of IDEs and separate heaters increases fabrication complexity. Here, a novel gas sensing platform based on a highly porous laser-induced graphene (LIG) pattern is reported. The LIG gas sensing platform consists of a sensing region and a serpentine interconnect region. A thin film of metal ( e.g. , Ag) coated in the serpentine interconnect region significantly reduces its resistance, thereby providing a localized Joule healing in the sensing region ( i.e. , self-heating) during typical measurements of chemoresistive gas sensors. Dispersing nanomaterials with different selectivity in the sensing region results in an array to potentially deconvolute various gaseous components in the mixture. The self-heating of the LIG gas sensing platform is first studied as a function of the applied voltage during resistance measurement and LIG geometric parameters ( e.g. , linewidth from 120 to 240 μm) to achieve an operating temperature from 20 to 80 °C. Systematic investigations of various nanomaterials demonstrate the feasibility of the LIG gas sensing performance. Taken together with the stretchable design layout in the serpentine interconnect region to provide mechanical robustness over a tensile strain of 20%, the gas sensor with a significant response (6.6‰ ppm −1 ), fast response/recovery processes, excellent selectivity, and an ultralow limit of detection (1.5 parts per billion) at a modest temperature from self-heating opens new opportunities in epidermal electronic devices. 

Abstract Incorporating photonic crystals with nanoplasmonic building blocks gives rise to novel optoelectronic properties that promise designing advanced multifunctional materials and electronics. Herein, the free‐standing chiral plasmonic composite films are designed by coassembling anisotropic plasmonic gold nanorods (GNRs) and rod‐like cellulose nanocrystals (CNCs). The effects of surface charge and concentration of the GNRs on the structure and optical properties of the CNC/GNR films are examined within this study. The CNC/GNR hybrid films retain the photonic characteristic of the CNCs host while concomitantly possessing the plasmonic resonance of GNRs. The negatively charged GNRs distribute uniformly in the layered CNCs host, inducing strong electrostatic repulsion among the CNCs and thus promoting the formation of a larger helical pitch than the case without GNRs. The positively charged GNRs decrease the chiroptical activity in the composite films with increasing the concentration of GNR, which is confirmed by the circular dichroism spectra. Notably, the surface plasmon resonances of GNRs enhance the fluorescence emission, which has been demonstrated by surface‐enhanced fluorescence signals in this work. This study sheds light on fabricating functional chiral plasmonic composite films with enhanced chiral plasmonics by utilizing CNCs as a dynamic chiral nematic template and adjusting surface charges.