Resonant Force Sensor Segmentation for Vibration Protection
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Solution Overview
Problem
Resonant sensors with nanometric dimensions are highly sensitive but prone to failure due to excessive forces from acceleration or impact, and existing solutions that dampen dynamic behavior reduce sensor performance.
Innovation Solution
A resonant force sensor design with a test body and strain gauge in separate environments, using a transmission mechanism to apply strain to the gauge while maintaining insulation, allowing the seismic mass to operate at higher pressure and protecting the resonator from excessive forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resonator with nanometric dimensions is placed in an environment at atmospheric pressure to dampen the dynamic behavior of the mass, then the resonator is protected from resonance and vibrations, but the resonator becomes substantially less performant
Solution Approach 1:
The sensor is divided into two separate environments: a first environment (atmospheric pressure) containing the seismic mass, and a second environment (vacuum or low pressure) containing the resonator. This segmentation allows each component to operate in its optimal environment, resolving the contradiction between protection and performance.
Solution Approach 2:
A transmission means acts as an intermediary between the seismic mass in the first environment and the resonator in the second environment. This intermediary transmits the mechanical action of the mass to the resonator while maintaining environmental separation, enabling both protection and performance.
2Measurement precision
If the resonator with nanometric dimensions is used to increase sensitivity to acceleration, then the sensitivity is significantly improved, but the resonator collapses under forces exceeding ten μN
Solution Approach 1:
The system is segmented into a robust seismic mass that handles high forces and a sensitive resonator that measures acceleration. The mass absorbs excessive forces through damping in the atmospheric environment, protecting the nanometric resonator from collapse while maintaining high sensitivity.
Solution Approach 2:
The atmospheric pressure environment serves as a cushioning medium before forces reach the resonator. By placing the resonator in a protected environment and using the transmission means to transfer only necessary mechanical action, the system preemptively protects the resonator from forces that would exceed its ten μN limit.
3Ease of operation
If the seismic mass is allowed to move freely to detect acceleration, then the acceleration detection is enabled, but the mass can vibrate at its resonance frequency and expose the nanoresonator to forces higher than its limits
Solution Approach 1:
The system separates the functions of acceleration detection (performed by the freely moving mass in the first environment) from resonator operation (performed in the protected second environment). This segmentation allows the mass to move freely for detection while the resonator remains protected from excessive forces through environmental isolation.
Solution Approach 2:
The transmission means acts as an intermediary that couples the freely moving mass to the protected resonator. It transfers the essential mechanical information for acceleration detection while filtering out harmful vibrations and forces, maintaining both detection capability and resonator reliability.
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 enhances sensitivity and performance by decoupling the seismic mass from the resonator, reducing the risk of damage and maintaining high sensitivity while allowing the sensor to operate effectively in varying pressure conditions, including exposure to fluids.
Implementation Method 1
at least one strain gauge with nanometric dimensions which is subjected to a strain because of the movement of the test body
Implementation Method 2
at least one resonator hanging between the support and the mass... set to vibrate at its resonance frequency... When the mass moves by the effect of an acceleration, the beam which is mechanically secured to the mass is compressed or stretched, which modifies its resonance frequency
Data Source
AI summary
A force sensor including a support, a test body, two strain gauges, mechanical transmission means between the test body and the strain gauges so that a movement of the test body applies a strain onto the strain gauges in a first direction of the plane of the sensor, the transmission means being hinged relative to the support about a second direction in the plane of the sensor, the test body being accommodated within a first volume, the strain gauges being accommodated within a second volume, insulated by sealed insulation means. The sensor includes a sacrificial layer, a nanometric layer, a protective layer and a micrometric layer. The test body and at least one portion of the support are formed in the substrate, the sealed insulation means are partially formed by the nanometric layer and by the sacrificial layer, and the strain gauges are formed in the nanometric layer.