Non-square Pressure Sensor Passages for Wearable Altitude Tracking
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Solution Overview
Problem
Wearable biometric monitoring devices with internally-mounted pressure sensors face issues due to skin occlusion and moisture trapping, leading to noise in altitude measurement data caused by skin seal fluctuations and trapped droplets, which affect the accuracy of altitude tracking.
Innovation Solution
Incorporating a pressure sensor passage within the device housing with a vent located offset from the skin and using passages with non-square cross-sections having a 2:1 or greater aspect ratio to prevent moisture interference and ensure consistent air pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the pressure sensor is mounted internally within the device housing, then the device achieves a compact form factor, but skin occlusion and moisture trapping occur leading to measurement noise
Solution Approach 1:
The patent divides the internal space into separate functional zones: a sensor chamber housing the pressure sensor, and a fluidic passage system with dedicated vent openings. This segmentation allows the sensor to be protected internally while maintaining a separate pathway for ambient air access, preventing skin occlusion from affecting measurements.
Solution Approach 2:
The patent introduces fluidic passages and vent openings as intermediary elements between the internal pressure sensor and the external environment. These passages serve as mediators that transmit ambient air pressure to the sensor while preventing direct contact between skin/moisture and the sensor, thus maintaining measurement accuracy in a compact form.
2Ease of manufacture
If conventional passages are used without specific cross-sectional geometry, then manufacturing is simpler, but moisture accumulates in the passages causing pressure fluctuations
Solution Approach 1:
The patent specifies that fluidic passages should have non-square cross-sections with aspect ratios of 2:1 or greater. This asymmetric geometry prevents moisture droplets from accumulating in the passages by eliminating flat surfaces where condensation can pool, thereby maintaining reliable pressure measurements without complicating the manufacturing process.
3Speed
If the vent is located adjacent to the skin-contacting surface, then ambient air access is direct, but skin seal fluctuations cause noise in pressure data
Solution Approach 1:
The patent positions vent openings on exterior surfaces that are not adjacent to skin-contacting areas, utilizing the three-dimensional space of the housing. This spatial repositioning allows ambient air to access the vent directly while eliminating the problematic interaction between skin movement and the vent opening, thus reducing pressure data noise.
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
The solution significantly reduces noise in pressure sensor data, enhancing the accuracy of altitude tracking by maintaining a clear fluidic connection to ambient air and preventing moisture-induced fluctuations.
Implementation Method 1
the first passage may allow air external to the wearable biometric monitoring device to travel from the first vent to the pressure sensor
Implementation Method 2
using passages with non-square cross-sections having a 2:1 or greater aspect ratio to prevent moisture interference
Data Source
AI summary
Passages for communicating ambient air to a pressure sensor within a housing are provided; such passages may have particular cross-sectional characteristics that result in higher-quality pressure data having less noise than may be obtained used passages having other cross-sectional characteristics.