In this paper, we present the design and characterization of a low-power low-cost infra-red emitter based on a tungsten micro-hotplate fabricated in a commercial 1- $\mu \text{m}$ silicon on insulator-CMOS technology. The device has a 250- $\mu \text{m}$ diameter resistive heater inside a 600- $\mu \text{m}$ diameter thin dielectric membrane. We first present electro-thermal and optical device characterization, long term stability measurements, and then demonstrate its application as a gas sensor for a domestic boiler. The emitter has a dc power consumption of only 70 mW, a total emission of 0.8 mW across the 2.5–15- $\mu \text{m}$ wavelength range, a 50% frequency modulation depth of 70 Hz, and excellent reproducibility from device-to-device. We also compare two larger emitters (heater size of 600 and $1800~\mu \text{m}$ ) made in the same technology that have a much higher infra-red emission, but at the detriment of higher power consumption. Finally, we demonstrate that carbon nanotubes can be used to significantly enhance the thermo-optical transduction efficiency of the emitter.