A gas-sensing apparatus with a self-powered microheater to reduce power usage and enhance efficiency when determining a presence of one or more gases in an air sample is provided. The gas-sensing apparatus includes a substrate, a sensing layer coupled to the substrate, and a heater element connected to the sensing layer and having at least one sheet. The sheet is made from a homogenous mixture of zinc powder and activated carbon. Oxygen from ambient air interacts with zinc ions in the zinc powder in an exothermic reaction to generate heat energy for use in heating the sensing layer to a desired temperature, thereby permitting the sensing layer at the desired temperature to detect the presence or ratio of the one or more gases in the air sample.
