a substrate;

an ionic thermoelectric sensing unit arranged on the substrate and comprising ionically conductive and electrically insulating material, wherein the ionic thermoelectric sensing unit is a voltage-producing unit having a first surface and a second surface spaced apart from and disposed opposite to one another, wherein the ionic thermoelectric sensing unit is configured to produce voltage via thermal diffusion of ions or via the Soret effect under a temperature difference between the first and second surfaces,

wherein the ionic thermoelectric sensing unit comprises a pair of elements spaced apart from one another along the substrate, and

wherein the pair of elements comprises a first element comprising a negative type thermoelectric material and a second element comprising a positive type thermoelectric material;

a thermal radiation absorber applied to at least one element of the pair of elements of the ionic thermoelectric sensing unit, wherein the thermal radiation absorber is configured to generate heat when exposed to thermal radiation, including infrared radiation;

a first electrical connector that connects respective first surface portions of a first surface of the pair of elements and a second electrical connector that connects respective second surface portions of a second surface of the pair of elements,

wherein the first electrical connector is disposed between the respective first surface portions and the thermal radiation absorber, and

wherein the thermal radiation absorber and the substrate are spaced apart from one another by the pair of elements; and

a support positioned to support the first electrical connector opposite the substrate,

wherein the support extends between the pair of elements and between the first electrical connector and the substrate, and

wherein the support is comprised of the negative type thermoelectric material or the support is comprised of the positive type thermoelectric material.