Pressure sensor

Claim 1

A novel subcombination for use in a pressure sensor apparatus of the type that is embodied in the human body for obtaining, non-invasively, indications of internal body pressure, particularly intracranial pressure, including a two-component communication means operative upon relative movement therebetween capable of communicating internal body pressure indications non-invasively to the exterior of the body and, wherein said internal body pressure indications are detected in the body by a flexible fluid-filled tambour, said novel subcombination comprising an elongated, substantially cylindrical housing, a bellows support member connected to said housing at one end thereof and defining one of the end walls of said housing, a fluid filling the complete interior of said housing for communcating with the fluid-filled tambour through the other end of the housing to enable the transfer of fluid to the interior of the housing in proportion to the body pressure detected by the fluid-filled tambour, an elongated, substantially cylindrical elastic bellows suspended in said fluid within said housing, one end of said bellows being connected to said bellows support member for supporting said bellows coaxially within said housing and in suspension within said housing, with the substantially cylindrical side wall portion of said bellows extending from said one end of the bellows to the other end of the bellows, coaxial with said housing, said substantially cylindrical side wall portion of the bellows having a diameter less than the diameter of said housing defining an annular space therebetween, said other end of said bellows comprising a first attaching means for attaching a first component of a communication means and being spaced from the other end of the housing free of any fixed connection with said housing, said other end of the housing comprising a second attaching means for attaching a second component of a communication means free of any fixed connection with said bellows, said bellows and said housing defining a first chamber, including said annular space and said bellows and said bellows support means defining a second chamber isolated from the first chamber, each of said first and second chambers being filled completely with fluid, means for placing said first chamber in fluid communication with the fluid-filled tambour, means for permitting fluid within said second chamber to flow into and out of said second chamber upon actuation of said bellows in proportion to the amount of fluid flowing into said first chamber, the movement of said bellows taking place in a direction substantially parallel to the major axis of said housing.