By sealing a diaphragm with less processes and lower cost and reducing deformation due to remaining stress, a stable and highly reliable pressure sensor construction is proposed. By forming a particular electrolyte 8 and by causing a current to flow between counter-electrode and the boron-doped diamond contact in contact with the liquid medium, actinides or polonium present in the liquid medium may be concentrated on the boron-doped diamond contact, and by this means the detection limit of the alpha emitters may be lowered. One of the passages contains a second blower to exhaust air from the air circulation system and from the independent pressure relief opening simultaneously. The first segment entry includes a first multicast group ID and the second segment entry includes a second multicast group ID. Used is a photosensitive silane coupling agent having a secondary amino group protected by an o-nitrobenzyloxycarbonyl group. Whereby, wires connected with the lamps inlayed in the groove strips are allowed to connect respectively with a control circuit board disposed on the fixing seat by burying and fixing them in the groove strips.