Zero‐Power, Optical Toxic Gas and Vapor Sensors Utilizing Printed Nematic Liquid Crystal Patterns on Selectively Reactive Substrates

Abstract Health risks affiliated with exposure to a wide variety of toxic gases and vapors are a certainty for first responders such as firefighters and HAZMAT team members but also for countless other professions from water purification and chemical manufacturing to the oil and gas industry, among others, and even the general public. Here the fabrication and testing of several prototypes for a novel toxic gas sensor platform based on ink‐jet printed nematic liquid crystal patterns are described. These sensors require zero power to operate and are characterized by high sensitivity down to highly relevant ppm and ppb levels, fast response times on the order of seconds, improved durability, and an overall design that is highly customizable by the potential end user. The response times of these sensors exponentially decrease with toxic gas concentration, thereby establishing the toxic gas diffusivity dependence of their mode of action. Such prototypes for two particular toxic gases, chlorine, and phosgene, performing interference testing in high humidity and smoke conditions as well as field testing with active firefighters are demonstrated.