Compression Glass Seal Window for Low-Noise PPG Wearables
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Solution Overview
Problem
Photoplethysmographic measuring devices in smartwatches face challenges with high optical noise, limited light scattering, and the risk of injury due to window damage, as they require high optical quality and robustness while minimizing user risk.
Innovation Solution
The use of a hermetically sealed window made of glass or glass ceramics in the form of a compression glass seal, integrated into an inorganic support, which reduces optical noise and enhances mechanical stability by incorporating a fiber-optic plate and surface structures to prevent injury upon damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional window design is used in photoplethysmographic measuring devices, then the device structure is simple, but optical noise is high and the risk of injury upon window damage is increased
Solution Approach 1:
The patent applies composite materials by combining glass or glass ceramic window material with a metal support structure featuring recesses and protrusions. This composite construction allows the window to achieve both high optical quality for reduced optical noise and enhanced mechanical stability through the integrated support structure, resolving the contradiction between optical performance and structural complexity.
Solution Approach 2:
The patent implements local quality by creating a non-uniform window structure with varying thickness - thinner at the center for optimal optical measurement and thicker at the edges where it integrates with the support structure. This localized variation in thickness allows the window to maintain high optical quality in the measurement area while providing enhanced structural stability and reduced optical noise at the boundaries.
2Strength
If a conventional window design is used, then manufacturing is simple, but mechanical stability is reduced and risk of injury upon damage is increased
Solution Approach 1:
The patent applies segmentation by dividing the window structure into distinct functional zones: a central thinner region for optical measurement and peripheral thicker regions integrated with the support structure. The support structure itself is segmented with recesses and protrusions that interlock with the window, providing enhanced mechanical stability while maintaining manufacturability through modular assembly.
Solution Approach 2:
The patent implements beforehand cushioning by designing the window with integrated support structures and varying thickness profiles that prevent complete fracture upon impact. The thicker peripheral regions and support integrations act as cushioning elements that absorb impact energy, preventing catastrophic failure and reducing injury risk while maintaining relatively simple manufacturing processes.
3Reliability
If the window is made more robust and fluid-tight, then hermetic sealing is improved, but the risk of injury upon window breakage is increased
Solution Approach 1:
The patent resolves this contradiction by creating a composite window structure combining glass/glass ceramic with metal support elements. The composite design provides hermetic sealing through the integrated support structure while the controlled thickness variations and support integrations ensure that upon breakage, the window fragments in a controlled manner with crater-shaped spalling that reduces injury risk compared to conventional monolithic windows.
Solution Approach 2:
The patent applies parameter changes by varying the window thickness parameter - thinner at the center for optical performance and thicker at the edges for structural integrity and controlled fracture behavior. This parameter variation allows the window to maintain hermetic sealing while changing the fracture characteristics to reduce injury risk, with the thicker edges preventing complete shattering.
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 solution reduces optical noise and increases the mechanical stability of the window, minimizing the risk of injury to the user while maintaining high optical quality for accurate pulse measurement.
Implementation Method 1
The at least one window is made of at least one of glass or glass ceramics... high optical quality... reduces optical noise
Implementation Method 2
The at least one window is fused into the inorganic support and the at least one window is in the form of a compression glass seal
Implementation Method 3
implemented as a compression glass seal with a fiber-optic plate... photoplethysmographic measuring device use a transmitter diode, in particular an LED, and a receiver diode, i.e. in particular a photodiode, which is used to measure the back-reflected light
Data Source
AI summary
An electronic device is provided which can be worn on the body or implanted into the body, such as in the form of a pulse watch and/or a smartwatch and/or an implant. The electronic device includes a photoplethysmographic measuring device. A transmitter diode and a receiver diode are arranged under a window made of glass or glass ceramics. The window is implemented as a compression glass seal and/or as a fiber-optic plate.