Inclined Optical Axis Probe for Tissue Signal Detection
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Solution Overview
Problem
Probes attached to thin living tissues, such as earlobes or neonatal skin, face challenges in accurately acquiring biological signals due to saturation of light-detecting elements and reduced signal-to-noise ratio.
Innovation Solution
The probe's light-emitting and light-detecting elements are positioned such that the optical axis is inclined and the light passes through both support structures in a way that scattered light enters the detector, reducing saturation and increasing the optical path length, while ensuring that the highest intensity light reaches the detector, thereby maintaining signal accuracy across varying tissue thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light-detecting element is positioned to receive light transmitted through thin living tissue, then the light intensity detected is high, but the light-detecting element becomes saturated and cannot accurately detect biological signals
Solution Approach 1:
The optical axis of the light-emitting element is inclined relative to the normal of the attachment surface, changing the spatial dimension of light propagation. This inclination causes the light to travel through a longer, oblique path in the tissue, increasing the optical path length and reducing the detected light intensity to prevent saturation while maintaining signal detection capability in thin tissues.
Solution Approach 2:
The patent changes the geometric parameter of the optical axis inclination angle. By adjusting this angle, the optical path length through the tissue is modified, which directly controls the detected light intensity and enables accurate biological signal detection without saturation across different tissue thicknesses.
2Measurement precision
If the optical path length through the tissue is increased to improve signal-to-noise ratio, then measurement accuracy improves, but the light intensity reaching the detector decreases
Solution Approach 1:
By inclining the optical axis, the light path transitions from a straight perpendicular trajectory to an oblique trajectory through the tissue. This dimensional change in the light path geometry naturally increases the optical path length without requiring additional tissue thickness, thereby improving signal-to-noise ratio while managing light intensity levels.
3Adaptability or versatility
If the probe is designed for universal application to various tissue thicknesses, then adaptability improves, but the light-detecting element performance varies across different tissue types
Solution Approach 1:
The inclined optical axis design creates a universal probe configuration that can be applied to various tissue thicknesses including thin tissues like earlobes and neonatal skin. The inclination angle is optimized to provide consistent performance across different tissue types, making the probe universally applicable while maintaining reliable signal acquisition.
Solution Approach 2:
By optimizing the inclination angle parameter, the probe achieves consistent performance across varying tissue thicknesses. This parameter optimization ensures that the optical path length adjustment compensates for differences in tissue thickness, maintaining reliable signal-to-noise ratio and preventing saturation across diverse application scenarios.
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 allows for accurate acquisition of biological signals irrespective of tissue thickness by preventing saturation and enhancing signal intensity, thus improving the reliability of pulse and oxygen saturation measurements.
Implementation Method 1
a light-detecting element 3. The light-detecting element has a light-detecting surface 31 configured to detect light that has been emitted from the light-emitting element 2, and that has been transmitted through the living tissue 100
Implementation Method 2
scattered light enters the detector
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A light-emitting element (2) is supported on a first supporting portion (42) such that an optical axis (21) is inclined relative to a direction (A) orthogonal to a first attachment surface (41). A light-detecting element (3) is supported by a second supporting portion (52) such that the optical axis (21) is placed on a light-detecting surface (31) under a condition that the first attachment surface (41) is attached to a first portion (101) of a living tissue of a subject and a second attachment surface (51) is attached to a second portion (102) of the living tissue (100). A passage (53) is located so as not to overlap with a first passage (43) as seen from a direction (B) orthogonal to the second attachment surface (51) under the same condition.