Optoelectronic Gas Sensing Platforms: From Metal Oxide Lambda Sensors to Nanophotonic Metamaterials

Real‐time monitoring is critical to improving safety and efficiency in chemical factories, oil and gas reservoirs, refineries, as well as land/marine/air transportation infrastructure. The lack of real‐time knowledge of constantly changing conditions in these systems causes delayed responses to critical situations such as equipment failure, chemical spills, and fire hazards, resulting in operational downtime and possible environmental damage. Sensing of hydrocarbon levels is of paramount importance in all these systems. To this end, electrical lambda sensors based on metal oxides that rely on changes in the electrical conductivity (permittivity) of the active oxide layer as a result of exposure to a target gas species have been used traditionally. These devices can suffer from low sensitivity, slow response, and bulky designs. Traditional optical sensors based on optrode and nondispersive‐infrared technology provide greater sensitivity, a wider dynamic range, and multispecies sensitivity. Recently the emergence of nanophotonic metamaterials for sensing various species shows a very promising path forward for realizing highly miniaturized, fast‐response devices. Herein, a comprehensive review of the evolution of optoelectronic gas sensing technologies is presented, not just focusing on a device‐level perspective but also examining the underlying physics and material considerations that are critical to obtaining optimal device performance.