Micro Viscometer with Segmented Piezoelectric Films
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Solution Overview
Problem
Existing viscometers face limitations in measuring fluid viscosity accurately, particularly for gases and with small fluid volumes, due to large size, high error margins, and inability to handle frequencies beyond low ranges, and most require substantial liquid quantities.
Innovation Solution
A micro viscometer design featuring piezoelectric films with optimized hexagonal or circular shapes, connected by micro channels, allowing for precise viscosity measurement using resonant frequency analysis, capable of handling both liquids and gases with minimal fluid volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional viscometers (Greenspan, Gillis) are used, then measurement precision is improved, but device size becomes large and frequency range is limited
Solution Approach 1:
The viscometer is segmented into two separate chambers (first chamber and second chamber) connected by a microchannel. Each chamber has its own piezoelectric film, allowing the system to function as a distributed sensor network rather than a single large unit. This segmentation enables miniaturization while maintaining measurement precision through the combined output of multiple sensing elements.
Solution Approach 2:
The invention transitions from traditional bulk acoustic wave resonators to thin-film piezoelectric membranes operating in a micro-scale dimension. By using piezoelectric films with thickness much smaller than their lateral dimensions, the device achieves high frequency operation (beyond 200 Hz) and compact size simultaneously, resolving the contradiction between precision and size.
2Volume of moving object
If crystal film viscometers are used, then device portability is improved, but measurement is limited to liquids requiring large volumes
Solution Approach 1:
The piezoelectric film-based viscometer is designed to measure viscosity of both liquids and gases, making it a universal sensor. The microchannel design allows gas flow through the sensing region, and the piezoelectric films respond to viscosity effects of both liquid and gas phases. This multi-functionality enables a single compact device to handle diverse fluid types without requiring large volumes.
Solution Approach 2:
The invention replaces gravity-dependent mechanical measurement systems with piezoelectric acoustic sensing. Traditional liquid-dependent viscometers rely on gravity to drive fluid flow, but piezoelectric films generate and detect acoustic waves that can propagate through both liquids and gases regardless of gravity, enabling universal fluid measurement in a compact format.
3Measurement precision
If capillary tube viscometers are used, then measurement capability is improved, but fluid volume requirement becomes large
Solution Approach 1:
The measurement system is divided into two chambers with a connecting microchannel, creating a distributed sensing architecture. Each piezoelectric film acts as an independent sensing element that requires minimal fluid volume to operate. The segmented design reduces the total fluid volume needed compared to a single large capillary tube while maintaining measurement precision through the combined response of multiple sensing zones.
Solution Approach 2:
The invention uses thin piezoelectric film membranes as the sensing element instead of rigid capillary tubes. These thin films vibrate in response to fluid viscosity and can be excited by piezoelectric actuators, requiring only minimal fluid volume to fill the microchannel and chambers. The thin-film structure enables precise measurement with micro-liter or even nano-liter scale fluid volumes.
4Adaptability or versatility
If Helmholtz resonator viscometers are used, then gas viscosity measurement is enabled, but frequency range is limited to low frequencies
Solution Approach 1:
The invention changes the operating parameters by using thin-film piezoelectric resonators with fundamental frequencies in the kilohertz range, compared to the low-frequency Helmholtz resonators. By adjusting the film thickness, material properties, and chamber dimensions, the system achieves high-frequency operation (kHz to MHz range) while maintaining gas viscosity measurement capability, thus expanding the frequency range beyond the limitations of traditional Helmholtz designs.
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 micro viscometer provides enhanced sensing capabilities, reducing error margins and enabling viscosity measurement across a broader frequency range, including gases, with improved accuracy and reduced fluid requirements.
Implementation Method 1
a first piezoelectric film disposed over the first thin film and a second piezoelectric film disposed over the second thin film
Implementation Method 2
enhanced sensing capabilities, reducing error margins and enabling viscosity measurement across a broader frequency range
Data Source
AI summary
A viscometer for measuring the viscosity of fluid. The viscometer includes: a first chamber and a second chamber separated from the first chamber; a micro channel connecting the first chamber to the second chamber; a first thin film disposed over the first chamber and a second thin film disposed over the second chamber; and a first piezoelectric film disposed over the first thin film and a second piezoelectric film disposed over the second thin film. At least one of the first and second piezoelectric films has a hexagonal shape if a longest distance between a center and an edge of the piezoelectric film is longer than a threshold range and a circular shape if the distance is shorter than the threshold range.