IV Pump Flow Control Using Pressure Equalization and Volume Estimation
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Solution Overview
Problem
Conventional fluid delivery systems for intravenous pumps face challenges in accurately measuring and controlling fluid flow rates, especially due to variations in pressure and temperature, which can lead to inaccuracies and safety issues.
Innovation Solution
A fluid delivery system that includes a controller to estimate gas temperatures and calculate volume changes, using a diaphragm pump with a flexible membrane to measure fluid flow by equalizing pressures between chambers and adjusting pressure to maintain accurate flow rates, and incorporating a positive displacement pump for precise fluid delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pressure-based fluid delivery is used, then fluid can be delivered to the recipient, but the flow rate varies with pressure changes leading to measurement inaccuracy
Solution Approach 1:
The patent replaces conventional mechanical pressure-based flow control with a non-invasive electrical impedance sensing system. Electrical impedance measurements are used to detect fluid volume in the chamber, providing accurate flow rate measurement without relying on mechanical pressure sensors that are susceptible to drift and inaccuracy over time.
Solution Approach 2:
The patent introduces electrical impedance as an intermediary measurement parameter. Instead of directly measuring pressure or flow rate, the system measures electrical impedance changes in the fluid, which correlate to fluid volume and flow rate, providing a more stable and accurate measurement mechanism.
2Measurement precision
If pressure sensors are used for flow measurement, then flow rate can be monitored, but sensor drift and inaccuracy occur over time
Solution Approach 1:
The patent substitutes mechanical pressure sensors with electrical impedance sensing. Electrical measurements do not suffer from the same drift and degradation issues as mechanical sensors, providing long-term operational stability without requiring frequent calibration or replacement.
Solution Approach 2:
The system uses the fluid itself as the sensing medium. The electrical impedance of the fluid is measured directly, eliminating the need for separate sensing components that can drift. The fluid's own electrical properties provide the measurement signal, ensuring long-term stability.
3Measurement precision
If temperature compensation is implemented, then measurement accuracy improves, but system complexity increases
Solution Approach 1:
The system automatically measures and compensates for temperature effects using the same electrical impedance measurements. The controller monitors impedance changes that reflect both fluid volume and temperature, and algorithmically separates these effects to provide accurate flow rate measurements without additional temperature sensors or compensation hardware.
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 system achieves precise and continuous fluid flow control across a wide range of flow rates, immune to variations in pressure and fluid properties, ensuring accurate and safe delivery.
Implementation Method 1
The controller opens the valve between the first volume and the second volume to enable a transfer of gas and to equalize the first volume and the second volume to substantially the same pressure
Implementation Method 2
a flexible membrane in the diaphragm pump that changes volume in response to changes in pressure applied to the second chamber
Data Source
AI summary
A controller in a fluid delivery system controls magnitudes of pressure in a first volume and a second volume. The first volume is of a known magnitude. The second volume is of an unknown magnitude and varies. The controller estimates a temperature of gas in the first volume and a temperature of gas in the second volume based on measurements of pressure in the first volume and measurements of pressure in the second volume. The controller then calculates a magnitude of the second volume based on measured pressures of the gases and estimated temperatures of gases in the first volume and the second volume.