To improve thermal insulation, a thermal infrared sensing element is carried on a sensor mount of a porous material and is spaced upwardly from a substrate by means of anchor studs projecting on the substrate. The sensor mount is formed with a pair of coplanar beams carry thereon leads extending from the sensing element. The leads and the beams are secured to the upper ends of the anchor studs to hold the sensing element at a predetermined height above the substrate. The beams and the leads are combined with each other by intermolecular adhesion such that the sensing element as well as the sensor mount can be altogether supported to the anchor studs.