Crossed Strain Sensor Frame for Bidirectional Movement Detection
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Solution Overview
Problem
Conventional strain sensors struggle to accurately detect movement in both elongating and shortening directions without requiring labor-intensive pretension adjustment, leading to potential measurement errors or failures.
Innovation Solution
A biometric sensor design featuring a ring-shaped frame with two cross-oriented stretchable strain sensor elements that deform to detect movement in both directions without pretension, utilizing a deformable frame and orthogonal sensor elements to capture changes in resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pretension is applied to the strain sensor element to enable detection in the shortening direction, then detection capability in the shortening direction is improved, but the complexity of application process increases and wearing comfort deteriorates
Solution Approach 1:
The sensor is divided into multiple strain sensor elements arranged in specific patterns (e.g., radial, circumferential, diagonal orientations) around the measurement target. By segmenting the detection function across multiple elements, the system can detect movements in both elongating and shortening directions without requiring pretension, as each element responds to specific directional strains.
Solution Approach 2:
The invention transitions from a single-dimensional detection approach (one strain sensor element) to a multi-dimensional arrangement (multiple elements in different orientations). This dimensional expansion enables comprehensive detection of movements in all directions around the measurement target, eliminating the need for pretension while maintaining detection reliability.
2Reliability
If pretension is excessive to ensure detection in the shortening direction, then detection capability is improved, but measurement accuracy deteriorates due to deviation from measurable range
Solution Approach 1:
Multiple strain sensor elements are distributed around the measurement target in specific orientations (radial, circumferential, diagonal). Each element operates within its optimal measurable range by detecting specific directional strains, preventing any single element from experiencing excessive tension that would cause measurement deviation.
Solution Approach 2:
Each strain sensor element is positioned and oriented to detect specific local strain characteristics. This local optimization ensures that each element operates within its accurate measurement range for its specific orientation, while the collective arrangement provides comprehensive detection capability without requiring excessive pretension.
3Ease of operation
If no pretension is applied to simplify application, then ease of operation is improved, but detection capability in the shortening direction deteriorates
Solution Approach 1:
The system uses multiple strain sensor elements arranged in different spatial orientations (radial, circumferential, diagonal directions) around the measurement target. This multi-dimensional arrangement enables detection of movements in all directions without pretension, as elements oriented in different directions naturally respond to corresponding strain patterns during both elongating and shortening movements.
Solution Approach 2:
The arrangement of multiple strain sensor elements in different orientations provides universal detection capability for movements in all directions. Each element serves multiple functions by detecting strains from different movement directions, eliminating the need for pretension while maintaining comprehensive detection 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
Enables noninvasive, easy application and accurate detection of movement in both elongating and shortening directions, enhancing wearing comfort and measurement sensitivity.
Implementation Method 1
a strain sensor element having a resistance value that can vary in accordance with stretching and recovering
Implementation Method 2
the frame is configured to be deformable at least in the lengthwise direction of the first strain sensor element and the lengthwise direction of the second strain sensor element
Data Source
AI summary
A strain sensor for detecting movement of a measurement target according to one example includes: a fixed member having a frame which is ring-shaped; and a first strain sensor element and a second strain sensor element, each of the first strain sensor element and the second strain sensor element being string-shaped or strip-shaped, and the first and second strain sensor elements being stretchable and recoverable in a lengthwise direction of the first strain sensor element and a lengthwise direction of the second strain sensor element. The first and second strain sensor elements extend across the frame and are disposed such that the first and second strain sensor elements cross each other, and the frame is configured to be deformable at least in the lengthwise direction of the first strain sensor element and the lengthwise direction of the second strain sensor element.