Microfluidic Flow Velocity Sensing via Optical Density Changes
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Solution Overview
Problem
Existing microfluidic systems face challenges in accurately measuring flow velocity in narrow microchannels due to clogging and the difficulty in using conventional methods, making it difficult to maintain a desired flow velocity for culture solutions.
Innovation Solution
A microfluidic device equipped with a first container, channel, light sources, light detectors, and an arithmetic processor that estimates flow velocity by measuring optical path length changes in the culture solution using laser light and optical density, allowing for easy measurement in narrow channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional flow velocity measurement methods are used in narrow microchannels, then measurement capability is maintained, but measurement precision deteriorates due to channel width limitations
Solution Approach 1:
The patent replaces conventional mechanical or physical flow measurement methods with an optical measurement system. By using light sources to illuminate the culture solution and light detectors to measure optical density changes, the system achieves flow velocity measurement in narrow microchannels without direct mechanical intervention, thereby maintaining measurement capability while improving precision in confined spaces.
Solution Approach 2:
The patent introduces optical density as an intermediary parameter to indirectly measure flow velocity. Instead of directly measuring flow velocity in the narrow channel, the system measures optical density changes of the culture solution caused by flow, then calculates flow velocity from these optical measurements. This intermediary approach enables accurate measurement in channels where direct measurement would be difficult.
2Reliability
If culture solution is continuously flowed through the microchannel, then flow velocity is maintained, but culture solution consumption increases
Solution Approach 1:
The patent implements a feedback control system where the arithmetic processor continuously monitors optical density measurements and adjusts the pump operation accordingly. By comparing measured optical density values with target values, the system regulates culture solution flow to maintain desired flow velocity while minimizing unnecessary flow, thereby reducing culture solution consumption while maintaining flow stability.
Solution Approach 2:
The patent employs dynamic adjustment of culture solution flow based on real-time optical density measurements. Rather than maintaining constant high flow rates, the system dynamically modulates pump operation to achieve the minimum necessary flow for reliable measurement and cell culture maintenance, optimizing the balance between flow velocity stability and culture solution conservation.
3Speed
If pump is used to move culture solution, then flow velocity control is achieved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical flow control mechanisms with a simplified system combining a pump and optical sensors. The pump provides basic flow movement, while flow velocity control is achieved through optical density measurement and arithmetic processing rather than complex mechanical regulation, thereby reducing overall device complexity while maintaining precise flow velocity control capability.
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 accurate and easy measurement of flow velocity in narrow channels, detects clogging early, and reduces culture solution consumption by circulating it between containers, while also estimating pH levels.
Implementation Method 1
a first light intensity that is an intensity of the first light that has passed through the culture solution in the first container at a first timing, and a second light intensity that is an intensity of the first light that has passed through the culture solution in the first container at a second timing different from the first timing
Implementation Method 2
an optical density of the culture solution in the first container obtained based on the first light intensity and an optical density of the culture solution in the first container obtained based on the second light intensity
Data Source
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AI summary
In a microfluidic device, a channel is connected to a first container, a culture solution flows through the channel, and a biological sample is disposed in the culture solution. The controller moves the culture solution in the channel to change a liquid amount of the culture solution in the first container. A first light source irradiates the culture solution with a first light passing through a liquid surface of the culture solution. A first light detector detects a first light intensity that is an intensity of the first light that has passed through the culture solution in the first container at a first timing, and a second light intensity that is an intensity of the first light that has passed through the culture solution in the first container at a second timing.