Patent ID: 7195609

Claim:
A piston stopper for an injection device, for injecting a medical or therapeutic product by axially advancing said piston stopper into a product container, comprising: a stopper body; a stopper body holder connected to a driven member of said injection device; at least one sealing element for sealing off said product container from said stopper body, wherein a membrane body is connected to a proximal end of the stopper body, such that the stopper body does not come in contact with the product to be injected, said membrane body comprises said at least one sealing; and a sensor coupled to the stopper body holder for detecting the pressure exerted by the product on a proximal end of the membrane body, wherein the sensor comprises a force transferring means that protrudes through an opening in the stopper body holder at a proximal end and extends axially through an opening of said stopper body and abuts an inner side of the membrane body.