An infrared radiation detector intended to operate around a preferred wavelength λp contained within a spectral band of interest that is defined between λmin and λmax, comprising a plurality of elementary detection micro-sites, each including a micro-detector provided with a membrane that is sensitive to radiation at least in the spectral band of interest and each being provided in a micro-cavity or micro-capsule defined by a substrate, by an upper wall used as a window that is transparent to said radiation in the spectral band of interest for at least some of said plurality of micro-sites and by side walls, said membrane being suspended above substrate by means of at least two support arms that include an electrically conducting layer, characterised: • in that the ends of said arms are anchored in side walls; • in that the side walls that define said micro-cavities or micro-capsules consist of two intimately joined parts: - a first lower part that adheres to substrate and forms semi-detached bases of the peripheral walls at each detection micro-site and locally comprises electrically conducting vertical connections that ensure electrical continuity with the electrically conducting layer of support arms; - a second part, the base of which is superposed on and physically attached to the top of said first part around the periphery of each micro-capsule and supports the upper wall or window which is substantially parallel to the substrate; • and in that electrical continuity between the at least two support arms and the substrate is obtained by conduction that extends transversely relative to the axis of said arms at the level of the bond line between the parts and of the side walls as far as a vertical connection element which is in electrical conduction with said substrate. • in that the ends of said arms are anchored in side walls; • in that the side walls that define said micro-cavities or micro-capsules consist of two intimately joined parts: - a first lower part that adheres to substrate and forms semi-detached bases of the peripheral walls at each detection micro-site and locally comprises electrically conducting vertical connections that ensure electrical continuity with the electrically conducting layer of support arms; - a second part, the base of which is superposed on and physically attached to the top of said first part around the periphery of each micro-capsule and supports the upper wall or window which is substantially parallel to the substrate; - a first lower part that adheres to substrate and forms semi-detached bases of the peripheral walls at each detection micro-site and locally comprises electrically conducting vertical connections that ensure electrical continuity with the electrically conducting layer of support arms; - a second part, the base of which is superposed on and physically attached to the top of said first part around the periphery of each micro-capsule and supports the upper wall or window which is substantially parallel to the substrate; • and in that electrical continuity between the at least two support arms and the substrate is obtained by conduction that extends transversely relative to the axis of said arms at the level of the bond line between the parts and of the side walls as far as a vertical connection element which is in electrical conduction with said substrate.