The growth in demand for sensors is exploding, driven by business and consumer need for information, increased functionality, and utility from their electronics and other devices. Only recently have smartphones and other wireless platforms become capable of delivering on that demand. Sensors of all types are being integrated into those devices, becoming an integral part of our everyday lives and building the Internet of Things. Some visionaries even foresee a world where trillions of sensors are deployed and worn, blanketing the globe. Gas sensors are an essential component of this movement as consumers and businesses demand information about themselves, their health, their operations and their environment. Chemical sensors, especially when integrated with smartphones and other wireless and wearable devices, provide a vast array of functionality, from informing people about their environment, air quality and safety, to diagnosing health conditions through breath analysis.