Absolute Pressure Sensor for Wearable Drug Delivery Monitoring
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Solution Overview
Problem
Conventional drug delivery devices fail to accurately detect and prevent under-delivery and over-delivery of medications due to factors like occlusions, changes in atmospheric pressure, and ambient temperature, leading to unintended medication flow without the patient's knowledge.
Innovation Solution
Incorporating an absolute pressure sensor within the drug delivery device to detect both ambient and relative pressures, allowing for real-time monitoring of medication flow and providing alarms for under-delivery or over-delivery conditions, and optionally using a flow sensor to confirm flow direction and amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pressure sensors measuring pressure relative to atmospheric pressure are used, then the device can detect occlusions and fluid path pressure, but it cannot detect changes in atmospheric pressure leading to under-delivery or over-delivery
Solution Approach 1:
The patent introduces an absolute pressure sensor as an intermediary measurement device that directly measures atmospheric pressure changes, complementing the existing relative pressure sensor. This mediator sensor provides the missing capability to detect atmospheric pressure variations that cause under-delivery or over-delivery events, resolving the limitation of the conventional relative pressure measurement system.
2Reliability
If the device monitors fluid path pressure to detect occlusions, then it can identify blockages, but it cannot distinguish between intended and unintended medication delivery events caused by atmospheric pressure changes
Solution Approach 1:
The patent implements a feedback mechanism where the absolute pressure sensor continuously monitors atmospheric pressure and provides real-time data to the control system. This feedback enables the system to distinguish between intended delivery events (where pressure changes match pump actuation) and unintended events (where pressure changes correlate with atmospheric pressure variations), preventing loss of information about delivery intent.
3Productivity
If the device uses conventional occlusion detection methods, then it can monitor pump actuation time, but it produces erroneous results due to drive system variabilities
Solution Approach 1:
The patent replaces the conventional mechanical timing-based occlusion detection method with a pressure-based detection system using absolute pressure sensors. This substitution eliminates the influence of drive system variabilities (friction, power sagging, mechanical variability) by directly measuring fluid path pressure, thereby improving measurement precision while maintaining detection speed.
4Device complexity
If the device does not monitor atmospheric pressure changes, then the device structure remains simple, but it cannot prevent under-delivery or over-delivery during activities like swimming or flying
Solution Approach 1:
The patent integrates the absolute pressure sensor into the existing drug delivery device architecture, enabling it to perform multiple functions: detecting atmospheric pressure changes, monitoring fluid path pressure, and providing data for both occlusion detection and unintended delivery event prevention. This multi-functionality approach increases reliability without proportionally increasing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise monitoring and alerting of medication delivery issues, ensuring safer and more effective drug administration by distinguishing intended from unintended delivery events and adjusting alarms based on severity and environmental factors.
Implementation Method 1
An absolute pressure sensor can be positioned within the fluid path of the drug delivery device and/or pump system. The absolute pressure sensor can detect both ambient pressure (e.g., absolute or atmospheric pressure) and relative pressure (gage or pumping pressure).
Implementation Method 2
When air is trapped in the fluid path, changes in atmospheric pressure can cause the trapped air to expand or compress and to displace (e.g., by suction) fluid into or out of the patient.
Implementation Method 3
When air is trapped in the fluid path, changes in ambient temperature can also cause the trapped air to expand or compress and to displace fluid into or out of the patient.
Data Source
AI summary
A wearable drug delivery device for monitoring unintended over-delivery and/or under-delivery of a stored liquid drug are provided. An absolute pressure sensor can be positioned within the fluid path of the drug delivery device. The absolute pressor sensor can detect both ambient pressure (e.g., absolute or atmospheric pressure) and relative pressure (gage or pumping pressure). Based on the detected pressures, the effects of external ambient pressure on air with the fluid path can be determined during both intended drug delivery events and unintended drug delivery events. In turn, under-delivery and/or over-delivery of the liquid drug can be determined. Based on the severity of the determined under-delivery or over-delivery of the liquid drug, alarms indicating different urgencies can be provided to the user.