Wearable Immersion Detection Using Pressure and Acceleration
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Solution Overview
Problem
Existing methods for determining if a wearable device is immersed in a fluid are often unreliable and energy inefficient, particularly when relying on continuous pressure monitoring to detect submersion, which can lead to damage from fluid exposure.
Innovation Solution
A method that compares acceleration signals with pressure data to determine fluid immersion, using changes in height and pressure over a predefined time period, allowing for a sealed device to include an air pressure sensor while preventing fluid entry when submerged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device is sealed to prevent fluid entry, then protection of internal components is improved, but the ability to include an air pressure sensor that requires venting is worsened
Solution Approach 1:
The device is divided into a sealed housing containing internal components and a separate venting mechanism with a hydrophobic membrane. This segmentation allows the main body to remain sealed for protection while the membrane vent provides controlled access for pressure sensing without compromising the seal.
Solution Approach 2:
A hydrophobic membrane acts as an intermediary between the internal pressure sensor and the external environment. This membrane allows water vapor and air pressure to pass through while blocking liquid water, enabling the pressure sensor to function without direct exposure to fluid that could damage internal components.
2Reliability
If continuous pressure monitoring is used to detect submersion, then detection reliability is improved, but energy consumption is worsened
Solution Approach 1:
Instead of continuous monitoring, the system uses periodic sampling of pressure data combined with acceleration data analysis. The processor evaluates pressure changes over specific time periods and compares them with expected pressure variations from device movement, enabling reliable submersion detection only when necessary and reducing overall energy consumption.
Solution Approach 2:
The system uses feedback from both pressure sensors and accelerometers to dynamically adjust monitoring behavior. By analyzing the relationship between pressure changes and device movement (acceleration), the system can distinguish between pressure changes caused by movement versus submersion, improving detection reliability while allowing the system to enter lower-power states when submersion is unlikely.
3Measurement precision
If pressure changes are used to detect submersion, then detection capability is improved, but false detection from random pressure fluctuations is worsened
Solution Approach 1:
The system merges data from multiple sensors (pressure sensors and accelerometers) to improve detection reliability. By combining pressure change detection with acceleration-based movement detection, the system can distinguish between legitimate submersion events and false positives caused by random pressure fluctuations during normal device movement.
Solution Approach 2:
The system performs preliminary analysis of pressure and acceleration data to establish baseline patterns of normal movement before making submersion determinations. By pre-processing the data to understand expected pressure variations from device movement, the system can filter out false positives while maintaining sensitivity to actual submersion events.
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 approach provides a reliable and energy-efficient mechanism to determine fluid immersion, enabling the inclusion of air pressure sensors while maintaining device sealing, thus protecting internal components.
Implementation Method 1
detecting a pressure within the device
Implementation Method 2
acquire an acceleration signal for the device
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
There is provided a device and a method of operating the device for determining whether the device is immersed in a fluid. An acceleration signal for the device is acquired (302) and a pressure within the device is detected (304). It is determined whether the device is immersed in a fluid based on a comparison of the acquired acceleration signal with the detected pressure (306).