| 摘要 |
A resistance thermometer is made by applying to a wire helix a liquid which coats the wire and extends between the turns through the whole length of the helix. The coating liquid is of high surface tension and low angle of contact, and when set, forms an electrically insulating support for the wire. The liquid may be glass, either molten or mixed as particles with water or alcohol in which case the assembly is heated to evaporate the solvent and melt the glass. The wire which may be Pt. has temperature-dependent resistance, and the helix may be formed on a mandrel, e.g. of Ni, the assembly then being heated in an oxygen-containing gas before the liquid is applied, so as to oxidize the exposed Ni surface so as to form an insulating layer. The mandrel is preferably tubular, and the wire may be a single helix extending along the mandrel, the mandrel then forming a return; or the helix may be double, both ends being at one end of the assembly. The helix is preferably spaced from the mandrel over the majority of its length. The liquid is preferably first applied to a part only of the helix and caused to set; adjustments, e.g. of resistance, may then be made to the as yet exposed portion of wire before it is then coated. The resultant capsule, which may have diameter as low as 0.01 inch, need not be cylindrical; it may, for example, form part of a toroid. It may be fitted into a hypodermic needle for measuring the temperature of a patient during an operation.ALSO:A wire resistance thermometer may be incorporated in a hypodermic needle for measuring the temperature of a patient during an operation. The thermometer, which may have diameter as low as 0.01 inch, comprises a wire helix encapsulated in e.g. glass. |
