A gas membrane sampling device, particularly for geological investigations, comprises a membrane element including a liquid-tight, gas-permeable membrane, a filler material contained in and stabilizing the membrane element, and a connection cable being adapted for conducting gas out of the membrane element through a bore hole to a surface of the earth’s. The back panel includes a top, two sides, a bottom, a securing flap integrally formed as part of the back panel, a hanging tab integrally formed at the top of the back panel, and a closing slot formed proximate one side of the back panel. The linear components deformed when the stent is set indwelling in vivo are composed of non-biodegradable metallic linear components and a plurality of biodegradable material-made linear components which are bonded to the non-biodegradable metallic linear components. When set to the reproduction mode, the thumbnail images stored in the buffer memory are read and displayed on a screen in a list format.