Differential Pressure Sensor with Deformable Membrane for Microfluidic Flow Measurement
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Solution Overview
Problem
Current microfluidic flow sensors face challenges such as inaccuracy, sensitivity to environmental conditions, and reliability issues, particularly when measuring flows of different fluids, due to complex designs and susceptibility to clogging, which limits their effectiveness in precise and rapid flow control.
Innovation Solution
A pressure sensor design featuring a deformable membrane with piezoresistive elements and a cavity minimally devoid of dead volume, allowing for precise measurement of pressure differences between fluids, integrated with a capillary restriction to prevent clogging and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal sensors are used to measure microfluidic flow, then flow measurement can be achieved, but accuracy is poor and the sensor is sensitive to environmental conditions
Solution Approach 1:
The patent replaces thermal sensors with a pressure-based measurement system. A deformable membrane with piezoresistive elements measures pressure differences caused by fluid flow, substituting thermal measurement mechanics with pressure measurement mechanics that are less sensitive to environmental conditions and provide higher accuracy
Solution Approach 2:
The patent changes the measurement parameter from temperature (thermal sensors) to pressure (membrane deformation). By measuring pressure differences across a restriction instead of thermal flux displacement, the system achieves better accuracy and reduced environmental sensitivity
2Measurement precision
If differential pressure sensors with restrictions are used to measure liquid flow, then flow measurement is possible, but response time is very low and reliability is reduced due to clogging
Solution Approach 1:
The patent segments the fluid path into distinct zones: a first fluid path for pressure measurement and a second fluid path for flow measurement. This segmentation allows the pressure sensor to operate without direct exposure to flowing fluid, eliminating clogging risks while maintaining measurement capability
Solution Approach 2:
The patent introduces a deformable membrane as an intermediary between the pressure measurement system and the flowing fluid. The membrane transmits pressure information without requiring fluid to pass through the sensor, preventing clogging while enabling differential pressure measurement
3Measurement precision
If two pressure sensors separated by a restriction are used, then flow rate can be measured, but the device complexity increases
Solution Approach 1:
The patent merges the pressure sensing function and membrane support into a single integrated component. The deformable membrane serves dual purposes: it supports the piezoresistive elements and simultaneously acts as the pressure-sensing element, reducing device complexity while maintaining measurement 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
The solution enables rapid, precise, and reliable measurement of fluid flow with reduced clogging risks, achieving a balance between reliability, speed, and cost-effectiveness in microfluidic applications.
Implementation Method 1
a deformable membrane (206) associated with means (212) for measuring the deformation of the membrane, the membrane being able to deform under the action of a fluid under pressure, preferably a liquid
Implementation Method 2
the means for measuring the deformation of the membrane being electrically connected to electrical contacts making it possible to collect an electrical signal depending on the pressure of the fluid
Data Source
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AI summary
The invention relates to a pressure sensor (213) comprising a support (200) in which a flexible membrane (206) is arranged substantially horizontally, bearing laterally on a ring (205), the assembly comprising sensor elements sensitive to the deformation of the membrane (212). According to the invention, the membrane can move vertically under the action of a pressurised fluid, preferably a liquid, applied preferably to the upper surface (231) of the membrane (206), the sensor elements (212) of which can be used to collect an electrical signal that is dependent on the pressure of the fluid. According to the invention, the upper surface (231) of the membrane (206) defines, in the housing of the support (200), the lower face of a cavity (208) into which two different pipes open, namely an inlet pipe (215) and an outlet pipe (216) (or vice-versa) for a fluid, allowing the fluid to flow in contact with the upper surface (231) of the membrane (206). The invention discloses an embodiment of the differential pressure sensor type.