| 摘要 |
An optical sensor for a delivery device having a piston (30) that displaces a substance, such as a fluid, from a reservoir (34). The optical sensor has a light source (42) and a detector array (44) for imaging encoding features disposed along a plunger rod (38) coupled to the piston. By virtue of the pattern of encoding features, an absolute position of the plunger rod relati ve to a fiducial position may be determined uniquely. Thus, the volume of fluid remaining in the reservoir, the rate of fluid delivery, and proper loading o f the reservoir may be accurately ascertained. Additionally, the encoding may serve to uniquely identify a version of the reservoir which may be supplied in various versions corresponding, for example, to differing concentrations of a therapeutic agent to be dispensed.
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