Patent ID: 8551045

Claim:
A fluid infusion system for infusing a medication fluid comprising: a reservoir adapted to contain the fluid and adapted for use with a pump drive system having a linear actuation member, the reservoir comprising: a proximal end adapted to connect to an infusion set; an open distal end; a cylindrical reservoir wall that extends along a longitudinal axis from the proximal end to the distal end; and a piston adapted to be slideably and frictionally mounted within the reservoir and forming a fluid-tight bather inside the reservoir; the piston comprising a piston body with at least one peripheral sealing portion made of a material having a first stiffness, said at least one sealing portion in sealing contact with the inside surface of the reservoir wall, wherein the piston further comprises a friction enhancing member adapted to be coupled to the piston, the friction enhancing member comprising a central section and one or more wall engaging portions coupled to the central section by a respective flexible shank portion bridging the one or more wall engaging portions with the central section, wherein the one or more wall engaging portions are at least partially made of a material having a greater stiffness than said first stiffness, the one or more wall engaging portions frictionally engaging the cylindrical wall of the reservoir and being arranged to exert a radially outwards directed force component against the cylindrical wall, and wherein the respective flexible shank portion(s) is/are so configured that the respective wall engaging portions(s) is/are movable relative to the central section only in directions substantially perpendicular to said longitudinal axis.