Detecting fill status for medical pump reservoir

A medical device system comprising:

• a reservoir configured to store a therapeutic fluid, the reservoir positioned in a chamber;
• and
• a reservoir fill level detector configured to detect a fill status of the reservoir, the reservoir fill level detector further comprising:
• a contact pad operably attached to the reservoir whereby the contact pad is attached to a bottom side of the reservoir and moves, in response to movement of the bottom side of the reservoir, in a predetermined path during the emptying and filling of the reservoir;
• a resistor strip mounted on the inside of the chamber whereby the resistor strip is in continual contact with the contact pad along the entire predetermined path;
• an energy source for providing a current along the resistor strip whereby the total resistance of the resistor strip is variable depending on the position of the contact pad;
• and
• a processor configured to monitor the resistance of the resistor strip.