Micropump Integrating Strain Gauge Flowmeter
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Solution Overview
Problem
Peristaltic membrane pumps lack integrated sensors for flow rate measurement, requiring external flowmeters that complicate miniaturization and increase size, especially in applications like implantable drug delivery devices, where precise and localized measurement is essential.
Innovation Solution
A micropump with deformable membranes integrates detection means, such as Wheatstone bridges with strain gauges, to measure membrane deformation and pressure differences across fixed geometry chambers, enabling accurate flow rate measurement within the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external flowmeters are connected to measure flow rate, then flow rate measurement capability is achieved, but device complexity and size increase
Solution Approach 1:
The flowmeter is integrated directly into the micropump structure by forming measurement chambers that share walls with the pump chamber. The deformable membrane serves dual purposes: as a pumping element and as a sensing element for detecting pressure differences. This merging eliminates the need for separate external flowmeters and their associated connections, thereby reducing device complexity while maintaining flow rate measurement capability.
Solution Approach 2:
The deformable membrane is designed to perform multiple functions simultaneously: it acts as the active pumping element that deforms to move fluid, and also serves as the sensing element where strain gauges detect pressure differences across the membrane. This multi-functionality reduces the number of separate components needed, simplifying the overall device structure while enabling accurate flow rate measurement.
2Measurement precision
If external flowmeters are connected to measure flow rate, then flow rate measurement capability is achieved, but device size increases
Solution Approach 1:
The measurement chambers are nested within the overall pump structure, sharing walls and space with the pump chamber. The first measurement chamber shares a wall with the pump chamber, and the second measurement chamber shares a wall with the first measurement chamber, creating a compact nested arrangement. This nesting allows the flowmeter functionality to be embedded within the pump volume rather than adding external bulk.
Solution Approach 2:
By merging the measurement chambers with the pump chamber through shared walls, the total device volume is reduced. The deformable membrane itself becomes the boundary between chambers, eliminating the need for additional separating structures and reducing overall device size while maintaining the ability to measure pressure differences for flow rate calculation.
3Reliability
If pressure sensors are positioned far from the pump, then measurement bias is avoided, but measurement accuracy decreases
Solution Approach 1:
The deformable membrane acts as an intermediary element that transmits pressure information from the pump chamber to the measurement chambers. By measuring pressure differences across the membrane in adjacent chambers, the system captures the pressure gradient directly at the pump location without requiring distant sensors. This intermediary approach maintains measurement reliability while improving accuracy by eliminating pressure drops in connecting channels.
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
This integration allows for precise and localized flow rate measurement, reducing the need for external sensors, simplifying the device, and improving accuracy and miniaturization, particularly beneficial for medical applications.
Implementation Method 1
The deformation of the membranes is obtained by means of piezoelectric platelets 131 positioned on the upper face 121S of the membranes.
Implementation Method 2
A micropump with deformable membranes integrates detection means, such as Wheatstone bridges with strain gauges, to measure membrane deformation
Data Source
AI summary
A micropump with a deformable membrane, including: a first chamber, one wall of which includes a first deformable membrane portion and an actuator of the first membrane portion; a second chamber including a second deformable membrane portion and a third chamber, including a third deformable membrane portion, the second chamber and the third chamber being connected together through a first channel, at least one of the second and third chambers being connected through a second channel to the first chamber; each of the second chamber and third chamber including a mechanism forming a detection gauge, but not including an activation mechanism.