Patent ID: 6494694
Filing Date: 2002-12-17
Classification: A61M,F04B,Y10T

Abstract:
A cassette that is adapted to engage a drive mechanism, for use in infusing a fluid into a patient, comprising:(a) a housing having a base on which is mounted a facing member, a fluid path being defined at least in part by the base and extending through the cassette between an inlet port and an outlet port, said fluid path including: (i) an inlet passage coupled in fluid communication with the inlet port; (ii) an outlet passage coupled in fluid communication with the outlet port; and (iii) a pumping chamber disposed between the inlet passage and the outlet passage; and (b) an elastomeric membrane that extends over the fluid path and when displaced into the pumping chamber, is adapted to force a fluid from the pumping chamber, said elastomeric membrane including a substantially T-shaped lip extending around and proximate its peripheral edge, said T-shaped lip being captured in an interference fit within a groove formed in opposed surfaces of the facing member and the base so that the elastomeric membrane is stretched taut as the facing member is joined to the base, said groove including inclined surfaces that are in interference with corresponding inclined surfaces on said T-shaped lip when the facing member is seated onto and joined to the base with the lip of the elastomeric membrane captured in the groove, a tension in the elastomeric membrane produced by said interference fit due to an interaction of the inclined surfaces of the groove and the T-shaped lip compensating for any inelastic stretching of the elastomeric membrane occurring when the elastomeric membrane is displaced into the pumping chamber, to thereby reduce errors in achieving a desired volume of a fluid infused by the cassette.