A radiation sensor is provided. The radiation sensor includes a substrate; a diaphragm positioned over the substrate; an absorbing layer which is configured to absorb infrared radiation; a supporting element arranged between the absorbing layer and the diaphragm such that a spacing gap is formed between the absorbing layer and the diaphragm; wherein the size of the spacing gap is in a range of about 3.6 micrometer to about 100 micrometer.