Flow Sensor Surface Wetting via Pressurized Fluid Restriction
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Solution Overview
Problem
Current flow sensors face challenges in accurately measuring fluid flow due to air boundary layers and micro-bubbles forming on the sensor surfaces, which attenuate ultrasonic signal transmission and affect volume accuracy in medical devices.
Innovation Solution
A method involving a flow sensor system with a single-use flow sensor and reusable base unit, where a flow restrictor is used to pressurize the fluid channel, wetting the internal surfaces and removing air bubbles, thereby enhancing ultrasonic signal transmission by ensuring the interior surfaces are fully wetted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flow sensor is initially subjected to fluid, then a boundary layer is formed, but micro-bubbles remain at the sensor surface causing signal attenuation
Solution Approach 1:
The patent applies preliminary pressurization action to the fluid before measurement to force it to wet the sensor surface and eliminate micro-bubbles. By pressurizing the fluid through a flow restrictor before it contacts the sensor, the surface is pre-conditioned to prevent bubble formation, thereby improving signal transmission reliability.
Solution Approach 2:
The patent uses hydraulic pressure applied through a flow restrictor to control fluid behavior at the sensor surface. By regulating the pressure and flow rate, the system ensures complete surface wetting and prevents air bubble entrapment, resolving the signal attenuation problem caused by micro-bubbles.
2Measurement precision
If pressure is applied to fluid, then surface area in contact with fluid increases, but micro-bubbles detach and absorb into fluid causing measurement errors
Solution Approach 1:
The system performs preliminary pressurization through a flow restrictor before fluid enters the sensor chamber. This pre-pressurization action ensures complete surface wetting and prevents micro-bubble formation at the sensor interface, thereby improving measurement precision without introducing significant air content into the fluid.
Solution Approach 2:
The patent changes the pressure parameter of the fluid as it passes through the flow restrictor. By controlling the pressure increase, the system optimizes surface wetting while minimizing bubble detachment and absorption, thus achieving accurate flow measurement without compromising fluid purity.
3Reliability
If surface topology has high asperity density, then capillary action increases, but micro-bubbles become lodged in cavities causing signal attenuation
Solution Approach 1:
The patent applies preliminary pressurization through a flow restrictor to force fluid into complete contact with the sensor surface. This pre-action overcomes the capillary trapping effect of surface asperities by providing sufficient pressure to push fluid into all cavities, preventing micro-bubble lodgment and ensuring reliable signal transmission.
Solution Approach 2:
The system uses hydraulic pressure through the flow restrictor to counteract capillary forces in surface cavities. By maintaining adequate pressure, the fluid completely wets the surface topology, preventing micro-bubbles from becoming lodged in asperity cavities and eliminating signal attenuation.
4Reliability
If a flow restrictor is used to pressurize fluid, then internal surfaces are wetted, but device complexity increases
Solution Approach 1:
The flow restrictor serves multiple functions: it pressurizes the fluid to ensure surface wetting, controls flow rate, and prevents micro-bubble formation. By making this single component multi-functional, the patent achieves reliable surface wetting without proportionally increasing device complexity.
Solution Approach 2:
The flow restrictor utilizes the inherent pressure differential created by fluid flow itself to achieve surface wetting. The system is designed so that normal operating flow conditions automatically provide sufficient pressure through the restrictor, eliminating the need for additional active pressurization mechanisms and reducing overall system 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
This approach improves the accuracy of fluid flow measurement by increasing ultrasonic signal strength, reducing errors in bolus delivery, and ensuring consistent and reliable fluid delivery in medical applications.
Implementation Method 1
pressurizing the fluid in the fluid channel between the fluid inlet and the flow restrictor to wet an interior surface of the fluid channel with the fluid
Implementation Method 2
pressurizing the fluid in the fluid channel between the fluid inlet and the flow restrictor to wet an interior surface of the fluid channel with the fluid
Data Source
AI summary
A method for readying a fluid sensor associated with a medical device includes attaching a flow restrictor to a fluid outlet of the fluid sensor. The fluid sensor includes a fluid channel, a fluid inlet at a first end of the fluid channel configured to couple to an outlet of an administrable fluid source, and the fluid outlet at a second end of the fluid channel. Fluid is delivered from the administrable fluid source to the fluid channel through the fluid inlet. A syringe actuation device including a force limiting device may be used to deliver the fluid. The fluid is pressurized in the fluid channel between the fluid inlet and the flow restrictor to wet an interior surface of the fluid channel with the fluid. The flow restrictor is removed from the fluid outlet.