Abstract: The invention relates to a sensor (1) for helium or hydrogen with a vacuum-tight housing (2), wherein a gas consuming cold cathode array (3, 4) is arranged, in addition to a selectively active passage (9) for the gas to be detected. According to the invention, in order to improve the properties of said sensor, the housing (2) is made of glass, components of the gas passage (9) include a membrane (18) made of a silicon material having the desired selective qualities, in addition to a silicon plate (19) which supports the membrane (18) and is provided with a plurality of openings (21) and a heating element (24). The housing (2) and the selectively active gas passage (9) are joined together without polymer and elastomer.