Room temperature sensing of volatile organic compounds using hybrid SnO nanoflower and Laser-Induced Graphitic carbon devices

Volatile organic compounds (VOCs) are a common risk to human health in industrial and domestic settings. VOCs are often present at concentrations that cannot be detected through human odor perception. VOC sensors are, therefore, urgently needed for home and workplace environmental monitoring, including wearable sensors for workers. However, current chemiresistive VOC sensors typically require high-energy fabrication processes with large environmental footprints, significant mass-loadings of critical raw materials and/or elevated operating temperatures, which hamper widespread, sustainable deployment. We demonstrate a simple, low-energy hybrid fabrication route for chemiresistive VOC sensors, comprising additively-produced laser-induced graphene (LIG) electrodes on plastic substrates, decorated with SnO nanoflowers. The SnO nanoflowers were synthesized below 100C at ambient pressure and offer a low-energy alternative to conventional SnO2 or other metal-oxide nanoparticle devices. These chemiresistive sensors can detect methanol vapor at room temperature (∼18C) and typical humidity levels (∼55% RH), with a limit of detection (170±40 ppm) below 8-hour worker safety exposure levels (200 ppm). The sensors also demonstrated stable DC resistance responses DeltaR/R = 9±2% to 710 ppm of methanol for over 21 days in ambient laboratory conditions. First principles density functional theory simulations are used to elucidate the origin of the performance of the LIG-SnO sensors. LIG-SnO hybrid sensors thus present a resource-efficient route to develop chemiresistive sensors for low-power applications, such as wearable worker safety or Internet of Things edge-sensing.