Abstract: A gas sensing device for detecting a to-be-detected substance in a respiratory gas exhaled by a user includes a housing permitting entrance of the respiratory gas, and a sensing module disposed in the housing. The sensing module includes a light chamber permitting the respiratory gas to pass therethrough, a light source unit emitting light into the light chamber, first and second light sensing units outputting respectively first and second detected signals indicating first and second detected intensities respectively of first and second portions of the light whose wavelengths fall within first and second wavelength ranges, respectively, and a processing unit electrically connected to the first and second light sensing units and determining, based on the first and second detected signals, that the to-be-detected substance exists in the respiratory gas when a difference occurs in each of the first and second detected intensities over time.

Abstract: An infrared thermal emitter includes a substrate, a light-emitting unit and an infrared-emitting unit. The light-emitting unit is disposed on the substrate in a laminating direction and has a light-exiting surface away from the substrate. The infrared-emitting unit is disposed on the substrate in the laminating direction to cover the light-emitting unit and includes a layered structure having a light-absorbing layer that is aligned with the light-emitting unit in the laminating direction. The light-absorbing layer absorbs light emitted from the light-emitting unit so as to be heated up and to generate infrared radiation.

Abstract: An infrared thermal emitter includes a substrate, a light-emitting unit and an infrared-emitting unit. The light-emitting unit is disposed on the substrate in a laminating direction and has a light-exiting surface away from the substrate. The infrared-emitting unit is disposed on the substrate in the laminating direction to cover the light-emitting unit and includes a layered structure having a light-absorbing layer that is aligned with the light-emitting unit in the laminating direction. The light-absorbing layer absorbs light emitted from the light-emitting unit so as to be heated up and to generate infrared radiation.