Wearable Device Skin Contact Security and Blood Pressure
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Solution Overview
Problem
Wearable devices, such as smart watches, lack secure authentication methods, allowing unauthorized users to access private information when the device is left unattended after initial authentication.
Innovation Solution
Incorporating a PPG sensor and processor to continuously monitor contact with the skin surface, ensuring that only authenticated and present users can execute sensitive functions by rejecting requests if the device is no longer in contact, and utilizing blood pressure estimation models to generate average blood pressure for user authentication and function execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If authentication is performed before executing functions, then user privacy and device security are protected, but the device remains vulnerable to unauthorized access when left unattended after authentication
Solution Approach 1:
The system performs preliminary skin contact detection before allowing authentication and continuously monitors contact status during function execution. This preliminary and ongoing verification ensures that the device is actually being worn by the authenticated user, preventing unauthorized access when the device is left unattended.
Solution Approach 2:
The system continuously monitors skin contact status through the PPG sensor and provides real-time feedback by rejecting or ignoring requests when contact is lost. This feedback mechanism dynamically adjusts security based on the current wearing state, automatically preventing unauthorized access without requiring user intervention.
2Object-affected harmful factors
If continuous skin contact monitoring is implemented using PPG sensor, then security against unauthorized access is enhanced, but device complexity and power consumption increase
Solution Approach 1:
The PPG sensor serves multiple functions: it detects skin contact status for security verification and simultaneously measures physiological parameters like blood pressure. By making the sensor multi-functional, the system enhances security without adding separate dedicated sensors, thereby limiting the increase in device complexity.
Solution Approach 2:
The system uses the user's own physiological signals (blood flow detected by PPG) as the authentication and monitoring mechanism. This self-service approach eliminates the need for external sensors or additional authentication hardware, reducing overall system complexity while maintaining high security.
3Measurement precision
If blood pressure estimation and averaging are performed, then accurate physiological monitoring is achieved, but processing time and computational resources increase
Solution Approach 1:
The system calculates blood pressure for each individual pulse duration and then averages multiple measurements over a predetermined time interval. This partial action approach (calculating for each pulse rather than continuous monitoring) achieves high measurement precision while limiting the time and computational resources required by processing only discrete pulse events.
Solution Approach 2:
Blood pressure measurement is performed periodically based on pulse durations rather than continuously. The system averages measurements over predetermined time intervals, creating a periodic measurement rhythm that balances measurement accuracy with acceptable processing time and computational resource usage.
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
Enhances security by preventing unauthorized access to sensitive functions and providing secure execution of tasks only when the device is properly worn and authenticated, while also monitoring and displaying user physiological data.
Implementation Method 1
a PPG sensor configured to generate a PPG signal
Implementation Method 2
calculate at least one blood pressure corresponding to each pulse duration according to at least one blood pressure estimation model and a time difference between two feature points within one pulse duration of the PPG signal
Data Source
AI summary
A wearable device including a skin sensor and a processor is provided. The processor is configured to receive an authentication data for authenticating a user when a wearing state of the wearable device is adjacent to a skin surface of the user, execute a predetermined function in response to a request when the authentication data matches a pre-stored data and the skin sensor determines that the wearable device does not leave the skin surface after the authentication data is received, and reject or ignore the request when the skin sensor determines that the wearable device leaves the skin surface before the predetermined function is executed. The processor further calculates blood pressures according to PPG signals detected by a PPG sensor of the skin sensor.