This invention provides a non-invasive CO2 sensing device, which comprises a conductive substrate, a signal conducting layer, and a gas sensing layer. The conductive substrate includes at least two electrodes spaced apart from each other. The signal conducting layer is disposed on the conductive substrate, and includes a plurality of carbon nanotubes that are randomly extended and crossed, and a plurality of metal oxide nanorods randomly attached to the carbon nanotubes. The carbon nanotubes and the metal oxide nanorods together form a composite material with a three-dimensional structure. The gas sensing layer is disposed on the signal conducting layer, and includes a polymer material with amino functional groups to adsorb CO2. In addition, this invention also provides a method for making the non-invasive CO2 sensing device stated above. |