| 摘要 |
1472829 Pressure gauges HAKIM CO Ltd 29 May 1975 [30 May 1974] 23493/75 Heading G1L [Also in Division A5] An implantable pressure sensor for sensing the pressure within a patient's skull 40, comprises a bag 11 formed from two circular sheets 25, 27 adhered together at their peripheries except at one position where a tube 31 communicates with the interior of the bag, the bag being filled with a radioopaque liquid 29 and the sheets being made of silicone rubber impregnated with beeswax, whereby as the pressure outside the bag increases, the bag is compressed to force liquid along tube 31. The sensor may be used in a hydraulic servosystem for measuring and/or controlling body-fluid pressures. The displaced liquid from bag 11 may operate a bellows which affects the operation of a servovalve for venting cerebral spinal fluid. Alternatively, the liquid may be electrically conductive, a predetermined displacement of liquid along tube 31 being arranged to bridge spaced electrodes in the tube to complete an external circuit to operate said valve. The cured bag is impregnated with wax by soaking in a mixture of beeswax and a heptane solvent, removing the bag from the mixture and then allowing the solvent to evaporate, the wax being encapsulated in the interstices of the material of the sheets. |
