Polarographic cell contg. platinum-silicon cathodes - silver reference anode, used partic. medically to measure partial pressure of oxygen

摘要

A polarographic cell for measuring partial pressures of oxygen contains a silicon substrate, a silver reference anode, and a large number of cathodes; these electrodes work in an electrolytic medium of alkaline metal halide, partic. KCl, sepd. from the medium to be analysed by a membrane permeable only to O2. The polarographic cell is mfd. by (a) oxidising a semiconductor substrate of Si to form a layer of SiO2; (b) eliminating this layer through a mask in the places where the cathodes will be formed; (c) depositing on the unit obtd. a layer of metal, partic. Pt, which can form an alloy (Pt-Si) which constitutes the cathode; and (d) eliminating the metal by a chemical which leaves the alloy intact. Subsequent stages involve the successive deposit of a layer of e.g. Zr and a layer of Ag, and elimination of these layers in the cathode area. The cell is used in the medical field to measure the partial pressures of oxygen in the blood and in respiratory: passages. The cell can be used, e.g. in a probe contg. KCl soln., closed by a PTFE membrane.