This work has as a main goal the characterization of thermal sensors, described as bolometer, which are dedicated to far infrared radiation detection. These sensors are fabricated using microfabrication techniques and the thin films are selective to wet etching. These mechanical microstructures are formed on silicon wafers using surface wet etching. As these structures are obtained using conventional techniques for integrated circuits manufacturing, it becomes possible perform monolithic integration of electronics and mechanical devices, allowing the integrated microsystems development. The porous gold or “gold black” used as a radiation absorber, showed absorption index greater than 80%.