Cantilever MEMS Densimeter With Flexure-Aligned Microcapillaries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing MEMS densimeters face issues with clogging in real-world environments and the need for pumps to continuously sample fluid, while cantilever-based approaches have lower Q factors and less direct resonance relationships, leading to inferior performance.
Innovation Solution
A MEMS densimeter design featuring a cantilever portion with microcapillaries aligned with flexure, including through-hole, blind-hole, and grid microcapillaries, which enhances fluid density response and allows for fluid trapping without the need for pumps, and includes inductors and strain gauges for precise measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microfluidic channel approach is used with a vibrating structure, then the resonator can operate in air or vacuum to achieve a high Q factor, but the device is susceptible to clogging in real world environments and requires a pump to continuously push fluid through the microfluidic channel
Solution Approach 1:
The patent extracts the fluid sampling function from the measurement structure by using a cantilever that is submerged directly in the fluid rather than requiring fluid to be pumped through microchannels. This eliminates the microfluidic channel network and pump requirements while maintaining the ability to measure fluid density through the cantilever's resonance frequency changes.
Solution Approach 2:
The cantilever structure serves multiple functions simultaneously: it acts as both the structural element for resonance-based density measurement and the fluid sampling interface. By being directly submerged in the fluid, the cantilever passively samples the fluid environment without requiring external pumping or complex microfluidic delivery systems.
2Device complexity
If a cantilever approach is used with the cantilever submerged in the fluid, then the device is robust to particulates and does not require a pump to sample fluid, but the lower Q factors and less direct resonance relationship to density lead to inferior performance
Solution Approach 1:
The patent introduces microcapillaries as a third-dimensional feature within the cantilever structure. These microcapillaries are formed through the thickness of the cantilever and filled with fluid, creating an internal fluid reservoir that enhances the cantilever's sensitivity to fluid density changes while maintaining the simplicity of direct submersion.
Solution Approach 2:
The cantilever is designed with microcapillary structures that create a porous-like internal architecture. These microcapillaries allow the cantilever to interact with the fluid environment while providing a larger effective surface area and volume for fluid density sensing, thereby improving measurement precision without requiring complex external systems.
3Measurement precision
If microcapillaries are introduced in the cantilever portion, then fluid density response is enhanced and fluid trapping is enabled without pumps, but the manufacturing complexity increases
Solution Approach 1:
The cantilever structure is segmented into multiple functional regions: the substrate, the cantilever portion extending from it, and multiple microcapillaries distributed through the cantilever thickness. This segmentation allows each component to be optimized independently while maintaining overall integration, facilitating manufacturing through modular fabrication processes.
Solution Approach 2:
The microcapillaries are pre-formed within the cantilever structure during the fabrication process rather than requiring post-manufacturing assembly. The microcapillary patterns are created using standard semiconductor manufacturing techniques such as photolithography and etching, allowing the fluid channels to be integrated into the cantilever before final assembly and deployment.
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 design provides enhanced fluid density measurement accuracy and robustness against particulates, improving performance by aligning microcapillaries with flexure and using inductors and strain gauges for precise strain measurement.
Implementation Method 1
an inductor disposed on the cantilever portion, wherein the inductor is configured to cause the cantilever portion to flexure relative to the fixed portion
Implementation Method 2
a strain gauge disposed at an interface between the fixed portion and the cantilever portion
Implementation Method 3
the cantilever portion defines a plurality of microcapillaries through at least a portion of a thickness of the cantilever portion, wherein the plurality of microcapillaries are aligned with the flexure
Implementation Method 4
The cantilever resonance is somewhat a function of the density of the fluid
Data Source
AI summary
A MEMS densimeter may include a cantilever portion defining one or more microcapillaries. The microcapillaries may provide an enhanced response to the fluid density. The microcapillaries may include microcapillaries which are aligned with flexure of the cantilever portion, such s through-hole microcapillaries, blind-hole microcapillaries, and grid microcapillaries. The microcapillaries may also include a plate microcapillary aligned normal to the flexure of the cantilever portion.