Patent ID: 8114055

Claim:
An implantable device for dispensing an active substance to a patient comprising: a housing defining: a chamber; an outlet for delivering said active substance to a target site within said patient, said outlet in fluid communication with the chamber; a capillary in fluid communication between said chamber and said outlet; a polymer filament located in the capillary for dynamically varying a flow rate of said active substance between said chamber and said outlet, said filament having a first state with a first length and a first cross sectional dimension and a second state with a second length and a second cross sectional dimension, the first length being less than the second length and the first cross sectional dimension being greater than the second cross sectional dimension, wherein the second cross sectional dimension of the filament allows for a greater flow rate than the first cross sectional dimension; and means for elongating the filament from the first state to the second state.