NOVELTY - Manufacturing a sensor device (100; 200; 300; 400) comprises providing a silicon wafer (10); manufacturing a first functional layer (20); manufacturing a second functional layer (30); manufacturing a third functional layer (40); and removing the portion of the wafer body (13) underneath the thermal sensor portion (21).    USE - The method is useful for manufacturing sensor device (claimed).    ADVANTAGE - The device manufactured is practically invisible.    DETAILED DESCRIPTION - Manufacturing a sensor device (100; 200; 300; 400) comprising a thermal sensor (23), a battery (33), an antenna (34), an electronic circuitry (22) and a solar cell (43) together integrally in one semiconductor carrier (10) comprises: providing a silicon wafer (10) having a wafer body (13) with two opposite, mutually parallel main surfaces (11, 12); in a first processing stage, manufacturing a first functional layer (20) in or on one (11) of the main surfaces, comprising a thermal sensor portion (21) with at least one thermal sensor (23), and manufacturing a functional layer (20) comprising electronic circuitry (22) arranged in a non-overlapping relationship with the thermal sensor portion (21); in a second processing stage following the first processing stage, manufacturing a second functional layer (30) having a material portion (32) containing a battery (33) and an antenna (34) arranged in a non-overlapping relationship with the thermal sensor portion (21); in a third processing stage following the first processing stage, manufacturing a third functional layer (40) having a material portion (42) containing one or more solar cells (43) arranged in a non-overlapping relationship with the thermal sensor portion (21); and in a fourth processing stage following the third processing stage, the portion of the wafer body (13) underneath the thermal sensor portion (21) is removed, such as to result in a recess (14) having a depth reaching from the bottom surface (12) side to the thermal sensor portion (21) in the first functional layer (20). An INDEPENDENT CLAIM is a sensor device comprising a thermal sensor (23), a battery (33), an antenna (34), an electronic circuitry (22) and a solar cell (43) manufactured integrally in one semiconductor body (13) with a method.