Reservoir Pressure Equalization via Piercable Member Venting
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Solution Overview
Problem
Medical devices with reservoirs for delivering fluidic media, such as insulin, face issues with pressure equalization, leading to inadvertent bolus delivery due to misalignment of components or external influences like altitude or temperature changes, and potential drawing of bodily fluids due to negative pressure.
Innovation Solution
A system that includes a structure with a chamber and a pierceable member to equalize pressure by allowing fluidic media to be expelled before the needle pierces the member, using a bias member and seal to maintain pressure equilibrium, and a base assembly with a fluid vent to accommodate pressurized fluid expulsion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reservoir is pressurized to ensure fluid delivery, then fluid delivery reliability is improved, but inadvertent bolus delivery occurs due to misalignment or external influences
Solution Approach 1:
The system performs preliminary pressure equalization through a vent channel before fluid delivery begins. The vent channel allows pressure to equalize between the reservoir interior and exterior, preventing inadvertent bolus delivery while ensuring reliable fluid delivery when needed.
Solution Approach 2:
The vent channel acts as an intermediary pathway that mediates pressure balance between the reservoir interior and exterior. This intermediary structure allows controlled pressure equalization without compromising the sealed fluid delivery system.
2Stress or pressure
If the reservoir is sealed to maintain pressure, then pressure control is improved, but negative pressure may draw bodily fluids into the reservoir
Solution Approach 1:
The vent channel serves as an intermediary that maintains pressure equilibrium between the reservoir interior and exterior. This prevents negative pressure differential that could otherwise draw bodily fluids into the reservoir through the sealed system.
Solution Approach 2:
The vent channel creates pressure equipotential conditions by allowing pressure equalization between the reservoir interior and exterior environments, eliminating pressure gradients that could drive unwanted fluid movement.
3Manufacturing precision
If the plunger shaft and driveshaft are perfectly aligned to prevent misalignment, then manufacturing precision is improved, but alignment errors still occur due to threading shifts
Solution Approach 1:
The vent channel performs preliminary pressure equalization before fluid delivery, compensating for any misalignment-induced pressure changes. This preliminary action ensures pressure stability even when manufacturing alignment is not perfect.
Solution Approach 2:
The system converts the potential harm of misalignment into a benefit by using the vent channel to equalize pressure. Any pressure changes from misalignment are automatically compensated, turning a manufacturing defect into a non-issue.
4Device complexity
If the reservoir system is simplified without pressure equalization, then device complexity is reduced, but inadvertent bolus delivery and fluid suction occur
Solution Approach 1:
The vent channel performs multiple functions: pressure equalization, prevention of inadvertent bolus delivery, and prevention of bodily fluid suction. This single multi-functional element maintains safe fluid delivery without significantly increasing device complexity.
Solution Approach 2:
The vent channel extracts the pressure equalization function from the complex mechanical alignment system, providing a simpler, more reliable method of pressure control that does not depend on precise manufacturing tolerances.
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
Prevents inadvertent delivery of fluidic media and prevents bodily fluids from being drawn into the reservoir, ensuring safe and controlled delivery by maintaining pressure equilibrium within the reservoir.
Implementation Method 1
allowing for pressure equalization of fluidic media contained within the reservoirs
Implementation Method 2
using a bias member and seal to maintain pressure equilibrium
Implementation Method 3
using a bias member and seal to maintain pressure equilibrium
Data Source
AI summary
Various embodiments of the present invention are directed to equalizing pressure in a reservoir containing fluidic media, possibly due to imperfect installation of the reservoir or an external influence such as an altitude or a temperature change. In various embodiments, fluidic media may be expelled from the reservoir through a needle and contained in an interior volume of a pierceable member before the needle pierces the pierceable member to establish a flow path to a user. In other embodiments, fluidic media may be expelled through a port of the reservoir into a chamber or to the outside environment. In further embodiments, fluidic media may be expelled through a channel in a plunger head and out a passage in the reservoir when the channel and passage are aligned. In other embodiments, fluidic media may be expelled through a valve, and the valve may be pierceable by a needle to establish a flow path to the user.