NIRS Sensor EMI Shielding with Transparent Conductive Layers
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Solution Overview
Problem
Near-infrared spectroscopy (NIRS) sensor assemblies face challenges with signal interference from external and internal electromagnetic interference (EMI) sources, as well as high manufacturing costs.
Innovation Solution
The NIRS sensor assembly incorporates a flexible circuit with a light source, light detector, and EMI shielding layers, including optically transparent and conductive EMI shielding, which reduces cross-talk between light source and detector wires and improves signal-to-noise ratio by forming Faraday cages around the electrical components while maintaining optical transparency for tissue measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EMI shielding layers are added to the NIRS sensor assembly, then signal quality and measurement precision are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent uses thin flexible EMI shielding films (conductive adhesive tape or mesh) instead of rigid shielding structures. These thin films are applied directly to the flexible circuit board, providing effective EMI protection while maintaining flexibility and minimizing structural complexity. The conductive adhesive tape is applied in specific patterns (around detector wires, over light source areas) to provide targeted shielding where most needed.
Solution Approach 2:
The EMI shielding is applied locally rather than uniformly across the entire device. Conductive adhesive tape is placed specifically around detector wires, over light source areas, and at critical signal pathways where EMI interference is most problematic. This localized approach provides effective shielding at critical points while minimizing overall device complexity and material usage.
2Measurement precision
If optically transparent EMI shielding materials are used, then signal quality is improved by reducing EMI, but manufacturing cost increases
Solution Approach 1:
The patent employs inexpensive conductive adhesive tapes and simple mesh materials for EMI shielding. These are cost-effective materials that can be easily applied during assembly. The shielding structures use simple geometric patterns (rectangular outlines, crosshatches) rather than complex expensive materials, making the overall device more affordable while maintaining effective EMI protection.
Solution Approach 2:
The patent optimizes the optical properties of shielding materials by selecting materials with specific transparency characteristics. The conductive adhesive tape and mesh are chosen to have optical transmission properties that allow sufficient light passage while maintaining EMI shielding effectiveness. This parameter optimization ensures both measurement quality and cost-effectiveness.
3Reliability
If multiple insulating layers are added around the EMI shielding layer, then reliability is improved by preventing electrical interference, but device complexity increases
Solution Approach 1:
The patent uses thin flexible insulating films and adhesive layers to provide electrical isolation. These thin insulating layers are applied between different conductive elements and around detector wires, providing reliable electrical isolation while maintaining flexibility and minimizing structural complexity. The insulating properties are achieved through standard flexible circuit board layers and adhesive tapes rather than thick rigid insulators.
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 effectively shields against EMI, enhances signal quality, and reduces manufacturing costs by using flexible and cost-effective materials, thereby improving the accuracy and efficiency of non-invasive biological tissue characterization.
Implementation Method 1
EMI shielding, which reduces cross-talk between light source and detector wires and improves signal-to-noise ratio by forming Faraday cages around the electrical components
Implementation Method 2
An optically transparent portion of the first insulating layer is aligned with the active area of the detector. An optically transparent portion of the EMI shielding layer is aligned with the active area of the detector. An optically transparent portion of the second insulating layer is aligned with the active area of the light detector.
Data Source
AI summary
A NIRS sensor assembly includes a light source, a light detector, a first insulating layer, an EMI shielding layer, and a second insulating layer. The first insulating layer covers an exposed portion of the light detector. An optically transparent portion of the first insulating layer is aligned with an active area of the light detector. The EMI shielding layer covers the first insulating layer. An optically transparent portion of the EMI shielding layer is aligned with the active area of the light detector. The second insulating layer covers the EMI shielding layer and the first insulating layer. An optically transparent portion of the second insulating layer is aligned with the active area of the at least one light detector.