Micro-fluidic Circuit for Accurate Tear Osmolarity Measurement
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Solution Overview
Problem
Current methods for measuring osmolarity, such as osmotic pressure, freezing point depression, and conductivity, often produce inaccurate or inconsistent results due to reflex tearing and evaporation issues when dealing with small fluid samples, particularly in diagnosing dry eye syndrome.
Innovation Solution
A system and method utilizing a micro-fluidic circuit with an integrated electrical circuit to measure electrical properties of a fluid sample, such as resistance or conductivity, on a nanoliter scale, minimizing evaporation and providing accurate osmolarity measurements by correlating these properties with osmolarity values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small fluid samples are taken to avoid reflex tearing, then patient comfort and measurement reliability improve, but the small samples immediately begin to evaporate leading to false readings
Solution Approach 1:
The device divides the fluid sample handling into separate functional zones: collection area, measurement area with electrodes, and waste area. This segmentation allows the small sample to be contained and measured quickly without exposure to air, preventing evaporation while maintaining reliability.
Solution Approach 2:
The patent introduces an intermediary measurement chamber that transfers the fluid sample from collection to analysis. This intermediate space allows controlled measurement conditions where evaporation is minimized, serving as a buffer between sample collection and final analysis.
2Measurement precision
If conventional osmolarity measurement techniques are used, then osmolarity can be determined, but the results are inaccurate or inconsistent due to reflex tearing and evaporation
Solution Approach 1:
The patent replaces complex mechanical measurement systems (osmotic pressure measurement, freezing point depression apparatus) with a simple electrical resistance measurement system. Electrodes measure the electrical resistance of the tear fluid, which correlates to ion concentration and osmolarity, providing accurate and consistent results without the complications of reflex tearing or evaporation.
Solution Approach 2:
The invention changes the measurement parameter from physical/chemical methods (osmotic pressure, freezing point) to electrical properties (resistance, conductivity). This parameter change enables accurate osmolarity determination through simple electrical measurements that are not affected by sample volume losses from evaporation or contamination from reflex tearing.
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 clinically feasible and accurate osmolarity determination of small fluid samples, like human tears, reducing evaporation effects and improving diagnostic reliability for conditions like dry eye syndrome.
Implementation Method 1
measuring a property of the fluid sample within the test site... measuring at least one electrical property (e.g., resistance, conductivity, etc.) of the fluid
Data Source
AI summary
An apparatus, system, and method for determining the osmolarity of a fluid. The apparatus includes at least one micro-fluidic circuit and at least one electrical circuit disposed in communication with the micro-fluidic circuit for determining a property of a fluid contained within the at least one micro-fluidic circuit.