Fluid Dispensing via Gas Pressure Feedback
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Solution Overview
Problem
Existing fluid dispensing and aspirating technologies lack accuracy and are affected by factors such as syringe fill-level, viscosity, and clogging, requiring complex setups or sensors in the liquid path, which are not simple, compact, or unaffected by these variables.
Innovation Solution
A pressure-driven apparatus and method using a controllable valve, pressure sensor, and pump to determine fluid volume based on gas pressure measurements, allowing precise dispensing or aspirating without prior knowledge of the chamber or fluid volume, independent of viscosity, and without a flow sensor in the liquid path, utilizing a cyclical pump and controller to manage operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Time Pressure Dispensing is used to achieve simple implementation, then ease of operation is improved, but manufacturing precision deteriorates due to lack of feedback on dispensed volume
Solution Approach 1:
The patent implements feedback by measuring the pressure difference between the initial state and final state of the gas in the chamber. This pressure feedback allows the system to calculate the dispensed volume accurately, resolving the contradiction by providing precision without complicating the operation. The controller uses this feedback to determine when the target volume has been dispensed.
Solution Approach 2:
The patent replaces mechanical flow meters or sensors in the liquid path with a pressure-based measurement system. By measuring gas pressure changes in the chamber headspace, the system determines liquid volume without mechanical contact, maintaining simplicity while achieving precision.
2Measurement precision
If flow meters are placed in the liquid path to measure dispensed volume, then measurement precision is improved, but device complexity increases and reliability decreases due to sensors in the liquid path
Solution Approach 1:
The patent introduces gas as an intermediary medium to indirectly measure liquid volume. Instead of placing sensors in the liquid path, the system measures gas pressure changes that result from liquid displacement. This intermediary approach maintains measurement precision while eliminating complex liquid-path sensors.
Solution Approach 2:
The patent extracts the measurement function from the liquid path entirely and places it in the gas phase. By taking out the sensing element from contact with the liquid, the system reduces device complexity and improves reliability while maintaining measurement accuracy through pressure-based volume calculation.
3Ease of manufacture
If conventional pumps are used to achieve compact size and lower cost, then ease of manufacture is improved, but manufacturing precision deteriorates due to pulsating flow
Solution Approach 1:
The patent employs periodic action by using a syringe pump that operates in controlled strokes or cycles. The system dispenses fluid in periodic increments and uses pressure feedback to determine when the target volume is reached, converting the inherently periodic pump action into a precisely controlled dispensing process that maintains both compactness and precision.
4Manufacturing precision
If syringe pumps are used to achieve precise dispensing, then manufacturing precision is improved, but device complexity and cost increase due to bulkiness
Solution Approach 1:
The patent implements self-service by using the system's own pressure measurements to control the dispensing process. The pressure sensor monitors the chamber conditions and automatically determines when the target volume has been dispensed, eliminating the need for complex external control systems and reducing overall device complexity while maintaining precision.
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
Enables precise, pulsation-free fluid dispensing or aspirating with no need for flow sensors in the liquid path, unaffected by viscosity or clogging, and in a compact, cost-effective manner, using existing chamber designs.
Implementation Method 1
a pressure sensor arranged to be in gaseous communication with the upper portion of the chamber, either directly in the chamber, connected to the chamber, or connected to a conduit leading to the chamber so as to measure the pressure therein
Implementation Method 2
a pump adapted to be in gaseous communication between a source of gas and the upper portion of the chamber
Implementation Method 3
a controllable valve connectable with the lower portion of the chamber so as to be in fluid communication with said lower portion of the chamber
Data Source
AI summary
A method dispenses and/or aspirates a predetermined volume of fluid from a chamber. The chamber includes a lower portion containing fluid and an upper portion containing gas. The method includes measuring an initial pressure in the upper portion and introducing or evacuating a known quantity of gas into or out of the upper portion. The volume of gas in the upper portion is determined based on the volume of gas introduced or evacuated from the upper portion and a measured change in pressure in the upper portion. An upper portion target pressure that will dispense or aspirate a predetermined volume of fluid is determined. A controllable valve is opened while the pressure in the upper portion of the chamber is monitored. Once the target pressure is reached, the predetermined volume of fluid has been dispensed or aspirated, and the controllable valve is then closed.