Microfluidic Flow Rate Sensor Using Droplet Tracer Detection
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Solution Overview
Problem
Current methods for measuring extremely small flow rates, such as those in hermetically sealed electronic packages and chemical reaction vessels, are ineffective and prone to errors, with a lower limit of measurement around 10 picoliters per second, and cannot directly measure flow rates accurately.
Innovation Solution
A microfluidic flow rate sensor with a droplet movement detector, which can be optical or electrical, generates signals based on the position and movement of a droplet within a channel, allowing for precise calculation of flow rates using a processor, with no lower limit of resolution for steady flow rates and the ability to monitor continuous changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods (vane deflection, propeller rotation, heated wire cooling) are used to measure flow rate, then the measurement can be performed with simple principles, but the lower limit of measurement is around 10 picoliters per second and cannot accurately measure extremely small flow rates
Solution Approach 1:
The patent replaces conventional mechanical measurement methods (vane deflection, propeller rotation) with a microfluidic system that uses a droplet as a tracer particle. The droplet's movement through the microchannel is optically detected, substituting mechanical force-based measurement with optical detection of fluid displacement, enabling measurement of extremely small flow rates below 10 picoliters per second.
Solution Approach 2:
The invention transitions from direct flow rate measurement to measuring the position and movement of a droplet tracer within the fluid stream. By tracking the droplet's position over time in a microchannel, the system indirectly measures flow rate with high precision, adding a spatial tracking dimension to the measurement process.
2Reliability
If conventional methods are used, then the device structure remains simple, but the reliability and accuracy for hermetically sealed package testing is insufficient
Solution Approach 1:
The patent introduces a droplet as an intermediary tracer element within the fluid stream. This droplet serves as a mediator that carries flow information from the microchannel to the optical detection system, enabling reliable measurement of extremely small flow rates that would otherwise be undetectable by conventional direct measurement methods.
Solution Approach 2:
The microfluidic flow rate sensor is designed with multi-functionality to handle various testing scenarios including hermetically sealed electronic package leak detection, chemical reaction vessel monitoring, and other applications requiring extremely sensitive flow rate measurement. The system can detect both inward and outward flow rates through the same microchannel structure.
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 microfluidic flow rate sensor provides accurate and reliable measurement of flow rates significantly lower than conventional methods, with no lower limit of resolution for steady flow rates and the capability to monitor continuous changes, overcoming the limitations of existing techniques.
Implementation Method 1
In one example, the droplet movement detector is an optical detector, such as a combination of a lens and an image capturing device.
Implementation Method 2
The position of the droplet may be determined based on a low resistance that is observed between electrical contacts at the position of the droplet.
Data Source
AI summary
A microfluidic flow rate sensor includes a droplet within a channel and a droplet movement detector that generates a signal based on the position and/or movement of the droplet within the channel. A processor determines the flow rate of a fluid through the channel based on the signal received from the droplet movement detector. In one example, the droplet movement detector is an optical detector, such as a combination of a lens and an image capturing device. In other examples, the droplet is electrically conductive, and at least a portion of the channel is conductive or includes electrical contacts. The position of the droplet within the channel is determined by observing the electrical characteristics of the channel.