Multi-axis Force Sensor with Strain Focusing Features
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Solution Overview
Problem
Existing miniature force sensors are not adequately miniaturized for placement at the distal end of small instruments, limiting their ability to provide precise force feedback and control, particularly in surgical applications.
Innovation Solution
A multi-axis force sensor design featuring a 3D body with strain focusing features and strain gauges, allowing for the detection of axial loads while canceling out non-axial loads, and protected against high temperatures and corrosive environments, enabling precise force measurement at the distal end of miniature instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If existing miniature force sensor designs are used, then force sensing capability is provided, but the sensor size cannot be sufficiently miniaturized for distal end placement
Solution Approach 1:
The force sensor is segmented into distinct functional components: a substrate forming a 3D body with strain focusing features, separate strain gauges positioned at specific locations, and an electrical circuit with terminals. This segmentation allows each component to be optimized independently for miniaturization while maintaining overall measurement precision through coordinated design of the segmented elements.
Solution Approach 2:
The patent applies local quality by creating strain focusing features at specific locations on the substrate where strain gauges are positioned. These localized features concentrate mechanical strain precisely where measurement is needed, enabling accurate force detection in a miniaturized configuration by enhancing the local mechanical properties rather than requiring the entire sensor to be large.
2Volume of moving object
If the sensor is miniaturized for distal end placement, then placement capability is improved, but reliability in harsh environments deteriorates
Solution Approach 1:
The patent replaces traditional mechanical force sensing mechanisms with a strain gauge-based electrical measurement system. Strain gauges convert mechanical deformation into electrical signals, which can be processed electronically. This substitution allows the miniaturized sensor to maintain reliability in harsh environments by using electrical rather than purely mechanical sensing elements that are more susceptible to environmental degradation.
3Measurement precision
If strain gauges are positioned to detect axial loads, then measurement precision for axial forces is improved, but sensitivity to non-axial loads increases
Solution Approach 1:
The patent employs asymmetric positioning of strain gauges on the substrate and designs strain focusing features with specific geometric asymmetries. This asymmetric configuration creates a measurement system that is inherently more sensitive to axial loads while being less responsive to non-axial forces, effectively using geometric asymmetry to filter out harmful lateral load interference.
Solution Approach 2:
The patent converts the potential harmful effect of non-axial loads into a beneficial filtering mechanism. By designing the strain focusing features and gauge positions to respond differently to various load directions, the sensor naturally amplifies axial load signals while suppressing non-axial interference, turning what could be measurement noise into a feature that enhances axial measurement precision.
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 enables further miniaturization of force sensors, providing enhanced precision and reliability for force feedback in surgical and other applications, ensuring accurate force measurement and resistance to harsh environments.
Implementation Method 1
an electrical circuit disposed on either one of the first surface or the second surface, the electrical circuit having at least one strain gauge
Implementation Method 2
the sidewall includes at least one strain focusing feature; wherein the at least one strain gauge is disposed proximate to the at least one strain focusing feature
Data Source
AI summary
A force sensor includes: a substrate that forms a three-dimensional, 3D, body disposed about a central z-axis of an r, θ, z-cylindrical coordinate system, the 3D body having a first surface, an second surface, and a sidewall disposed between the first and second surfaces, wherein the sidewall at least partially encloses a void in the 3D body that extends from and through the first surface to and through the second surface; an electrical circuit disposed on either one of the first surface or the second surface, the electrical circuit having at least one strain gauge, and a plurality of electrical terminals electrically connected to the at least one strain gauge; wherein the sidewall includes at least one strain focusing feature; wherein the at least one strain gauge is disposed proximate to the at least one strain focusing feature.