Force Sensor Boss Structure for Diaphragm Rigidity
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Solution Overview
Problem
Force sensors face challenges in accurately and reliably measuring external forces due to issues with durability and rigidity, particularly in medical and industrial applications, where high precision and resistance to over-deflection are required.
Innovation Solution
The design incorporates a sense die with a diaphragm and a boss extending from it, which increases rigidity and durability, along with an actuation assembly that transmits forces to the diaphragm, ensuring accurate force measurement and preventing over-deflection through the use of a capture feature that centers the force receiving feature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the diaphragm is made thinner to improve sensitivity, then measurement precision is improved, but durability and resistance to over-deflection deteriorate
Solution Approach 1:
The patent applies local quality by creating a boss structure with varying thickness - thinner at the sensing location for sensitivity, and thicker at the periphery for durability. The boss extends from the diaphragm surface and provides localized structural reinforcement without compromising the thin diaphragm's sensitivity to applied forces.
2Measurement precision
If the diaphragm is made thinner to improve sensitivity, then measurement precision is improved, but rigidity deteriorates
Solution Approach 1:
The boss structure provides localized rigidity enhancement at the periphery while maintaining thin thickness at the sensing area. This creates a gradient structure where the diaphragm is thin and compliant at the center for sensitivity, but has increased rigidity at the edges through the boss extension.
3Reliability
If the boss structure is added to increase rigidity, then durability is improved, but device complexity increases
Solution Approach 1:
The boss structure is integrated directly into the diaphragm as a monolithic structure, merging the reinforcement feature with the diaphragm itself rather than adding a separate component. This reduces assembly complexity while providing the needed structural support.
4Measurement precision
If the force receiving feature is centered on the diaphragm, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The centering function is merged into the boss structure itself, which naturally positions the force receiving feature at the center of the diaphragm. The boss acts as both a structural reinforcement and a positioning feature, eliminating the need for separate alignment mechanisms.
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 configuration enhances the force sensor's ability to accurately measure forces across a range of applications by providing increased durability and preventing permanent deformation, leading to improved reliability and precision in output signals.
Implementation Method 1
one or more sensing elements (e.g., piezoresistive elements) positioned on the diaphragm
Data Source
AI summary
A force sensor may include a sense die mounted to a substrate and an actuating assembly for transmitting an external force to the sense die. The sense die may include a diaphragm, a boss extending from the diaphragm, and one or more sensing elements (e.g., piezoresistive elements positioned on the diaphragm). The actuation assembly may include a force receiving feature configured to receive an external force at a first end and transfer at least a portion of the received external force through a second end to the diaphragm via intimate contact with a bottom side of the boss. In some cases, the force sensor may also include signal conditioning circuitry.