Importance

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Abstract

A pressure-sensitive overfill protection system for a refillable drug delivery device includes a collapsible link which, in a preferred embodiment, comprises an aneroid having an internal volume of gas at a reference pressure. The collapsible link, in its expanded state, supports on inlet valve in an open position to permit the ingress of new drug fluid into a bellows reservoir. The external surface of the aneroid is exposed to the bellows pressure. When the bellows pressure exceeds the reference pressure, the aneroid collapses and permits the inlet valve to move to a closed position under a biasing force provided by a spring. Further flow of new drug fluid into the drug delivery device is thereby prevented. Moreover, the closure of the valve provides a large increase in pressure is experienced in the refill device and may therefore be sensed by a clinician. Because the overfill protection system is pressure sensitive, it may be used with different sized bellows without modification.

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First Claim