Conformable Physiological Sensor with Neutral Axis Optical Mounting
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Solution Overview
Problem
Existing physiological sensor systems cause discomfort and damage to sensitive skin due to pressure points and stiffness, particularly when applied to neonates, and struggle to adhere to small radius compound curvatures.
Innovation Solution
A non-invasive, disposable sensor with a multi-layered structure featuring a flexcircuit assembly and a patient adhesive layer, where optical components are positioned along a mechanical neutral axis to maximize flexibility, and a hydrocolloid or silicone-based adhesive is used to secure the sensor without causing pressure points, allowing it to conform to small radius curvatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If optical components are made thicker to ensure structural integrity, then mechanical strength is improved, but pressure points are generated causing skin damage
Solution Approach 1:
The sensor utilizes a flexible printed circuit board (FPC) as the substrate, which is thin and conformable. Optical components are mounted on this flexible substrate rather than using thick rigid structures, allowing the sensor to conform to curved surfaces without creating pressure points while maintaining structural integrity through the flexible circuit design.
Solution Approach 2:
The patent positions optical components along the mechanical neutral axis of the FPC, distributing them in a specific spatial arrangement that eliminates pressure points. By changing the dimensional arrangement from vertical protrusion to lateral distribution along the neutral axis, the design maintains optical functionality while avoiding skin contact issues.
2Adaptability or versatility
If the sensor is made more flexible to conform to small radius curvatures, then adaptability is improved, but structural stability deteriorates
Solution Approach 1:
The FPC substrate inherently provides flexibility allowing the sensor to conform to small radius curvatures of neonatal heads. The flexible nature of the circuit board maintains structural stability through its material properties and construction, enabling both adaptability to curved surfaces and structural integrity during use.
Solution Approach 2:
The sensor design allows dynamic adaptation to different head shapes and sizes through the flexible FPC substrate. The structure can dynamically adjust its shape to match the patient's anatomy while maintaining electrical and optical connectivity, providing both flexibility and stability.
3Strength
If adhesive coverage is increased to improve adhesion, then bond strength is improved, but skin irritation increases
Solution Approach 1:
The adhesive is applied locally only at the periphery of the sensor pad rather than covering the entire surface. This peripheral adhesive application provides sufficient bonding strength to secure the sensor while minimizing the total adhesive contact area with the skin, thereby reducing the risk of irritation and allowing skin breathing.
4Measurement precision
If the sensor structure is made more rigid to maintain calibration, then measurement precision is improved, but ease of application deteriorates
Solution Approach 1:
The FPC substrate provides the necessary flexibility for easy application to curved surfaces while the optical components are positioned along the mechanical neutral axis to maintain their relative positions and calibration. This arrangement ensures that the sensor can be easily applied and removed while preserving measurement precision.
Data Source
AI summary
A sensor for measuring physiological characteristics includes a circuit assembly, at least one material layer, and an adhesive layer that extends beyond an outer edge of the circuit assembly. The at least one material layer forms an adhesive edge around the perimeter of the sensor.