Infusion Pump Plunger Position Monitoring via Shaft Sensing
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Solution Overview
Problem
Infusion pump devices lack the ability to accurately monitor the remaining fluid in the reservoir and detect anomalies in the drive system, such as occlusions or disengagement, due to the reservoir being obscured and potential malfunctions within the pump drive system.
Innovation Solution
Incorporating a sensing arrangement that detects a detectable feature on a shaft coupled to the plunger, allowing for the measurement of the shaft's position and determining the remaining fluid amount, and identifying anomalous conditions by comparing the expected and measured shaft positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reservoir is contained inside a housing, then the device structure is protected and compact, but the user cannot visually monitor the remaining fluid in the reservoir
Solution Approach 1:
A sensing arrangement acts as an intermediary between the shaft position and the user interface. The sensor detects the position of a detectable feature on the shaft (which moves with the plunger), converts this mechanical position into an electrical signal, and enables electronic monitoring of fluid level without requiring direct visual access to the reservoir interior.
Solution Approach 2:
The patent replaces direct visual mechanical observation with an electronic sensing system. Instead of requiring the user to see the fluid level directly, a sensor detects shaft position and this information can be displayed electronically or used to trigger notifications, substituting optical mechanical observation with electronic detection.
2Device complexity
If the reservoir is obscured from the user, then the pump drive system is more compact and protected, but the user cannot detect anomalies such as occlusions or disengagement
Solution Approach 1:
The sensing arrangement provides continuous feedback about shaft position to the control system. By comparing the actual shaft position (measured by the sensor) with the expected shaft position (based on motor rotation), the system can detect anomalies such as occlusions, disengagement, or drive train failures and notify the user, maintaining reliability without requiring visual access.
Solution Approach 2:
The patent replaces visual mechanical inspection with electronic position sensing and computational anomaly detection. The sensing arrangement electronically monitors shaft position, and the control system computationally compares expected versus actual positions to detect anomalies, substituting visual mechanical monitoring with electronic detection systems.
3Measurement precision
If a sensing arrangement is added to detect shaft position, then fluid level monitoring and anomaly detection are enabled, but the device complexity increases
Solution Approach 1:
The patent extracts only the essential sensing function needed for position detection. The sensing arrangement is designed to detect a specific detectable feature on the shaft (such as a magnet, reflector, or mechanical marker) without requiring complex sensor assemblies. This minimalistic sensing approach enables position measurement while limiting the increase in device complexity to only what is necessary for the core function.
Data Source
AI summary
Apparatus are provided for infusion devices and related control systems and methods. In one embodiment, an infusion device includes a voided portion adapted to receive a shaft portion that includes a shaft coupled to a plunger of a reservoir. The shaft portion includes a detectable feature, and the infusion device includes a sensing arrangement proximate the voided portion to sense the detectable feature. In some embodiments, a control module is coupled to the sensing arrangement to determine a remaining amount of fluid in the reservoir based at least in part on the sensed position of the detectable feature. In other embodiments, the control module identifies an anomalous condition based at least in part on the sensed position of the detectable feature.