Multi-Wearable PPG Authentication Using Pulse Transit Time
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Solution Overview
Problem
Existing biometric authentication systems using wearable devices struggle to provide a secure and unique authentication method that is difficult to forge, especially when relying on cardiovascular signals like photoplethysmography waveforms.
Innovation Solution
The method determines pulse time and inter-beat intervals based on timestamps from photoplethysmography waveforms sensed by multiple wearable devices on different regions of the user, using synchronized timestamps to authenticate the user by comparing these values against a reference pulse time and interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional biometric authentication systems use single-device photoplethysmography waveforms, then the authentication process is simple and quick, but the security and uniqueness of authentication is insufficient and easy to forge
Solution Approach 1:
The patent divides the authentication system into multiple independent wearable devices (first wearable device and second wearable device), each sensing PPG waveforms at different locations. This segmentation increases security by requiring coordination between multiple devices rather than relying on a single device, thereby resolving the contradiction between authentication security and system complexity.
Solution Approach 2:
The patent introduces a temporal dimension by measuring pulse transit time (the time difference between pulse detections at different locations) in addition to the spatial dimension of multiple devices. This adds a new measurement dimension that enhances authentication uniqueness and security while maintaining reasonable system complexity through efficient time-based differentiation.
2Measurement precision
If the system uses multiple wearable devices to sense PPG waveforms at different locations, then the uniqueness and security of authentication is enhanced, but the measurement and processing complexity increases
Solution Approach 1:
The patent extracts key temporal features (timestamps of specific waveform features like peaks or troughs) from the PPG waveforms sensed by multiple devices. By focusing on extracting these specific temporal markers rather than processing the entire waveform data, the system achieves precise pulse time measurements while reducing processing complexity.
Solution Approach 2:
The patent uses the pulse transit time as an intermediary parameter that bridges the PPG waveforms from multiple devices. This intermediary measurement simplifies the comparison process between devices by reducing complex waveform data to a single time-difference value, making measurement and authentication more manageable while maintaining precision.
3Reliability
If the system compares pulse times and inter-beat intervals against reference values, then authentication reliability is improved, but the system requires time synchronization and reference data management
Solution Approach 1:
The patent employs periodic measurement of pulse transit time and inter-beat intervals at regular time intervals. This periodic action allows the system to maintain reference values through continuous updates while simplifying synchronization requirements, as each measurement cycle independently compares current data against established references without requiring complex continuous synchronization protocols.
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
Provides a secure and unique authentication method that is difficult to forge, leveraging the uniqueness of individual vascular physiology and time-varying characteristics of pulse times and intervals, enhancing security and reliability.
Implementation Method 1
a first photoplethysmography waveform sensed by a first wearable device on a first region of the user and a timestamp associated with the feature within a second photoplethysmography waveform sensed by a second wearable device on a second region of the user
Data Source
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AI summary
The disclosure relates to a method comprising: receiving a request to authenticate a user; determining a pulse time based on a timestamp associated with a feature within a first photoplethysmography waveform sensed by a first wearable device on a first region of the user and a timestamp associated with the feature within a second photoplethysmography waveform sensed by a second wearable device on a second region of the user; and authenticating the user based on the pulse time