Novel gas sensing platform based on a stretchable laser-induced graphene pattern with self-heating capabilities†
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.