Photodetector Array Biometric Detection for Wearables
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Solution Overview
Problem
Conventional biometric detection systems using photodetector arrays face challenges such as requiring specific user actions, reduced accuracy due to user movement, and increased costs associated with multiple light sources and additional hardware like accelerometers.
Innovation Solution
The use of a photodetector array with a plurality of photodetectors allows for the collection of biometric data across various touch events and movements, enabling passive, continuous heart rate measurements without the need for proactive user actions or multiple light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single photodetector is used for biometric detection, then the device complexity is reduced, but the measurement precision and reliability are insufficient to accurately capture biometric data during user movement
Solution Approach 1:
The photodetector is divided into multiple individual photodetectors arranged in an array, where each photodetector captures light from a specific spatial location. This segmentation allows the system to track which photodetectors are activated during user interaction, enabling accurate biometric measurement even when the user's position varies, thereby improving measurement precision without requiring a completely complex system redesign
Solution Approach 2:
The system transitions from a single-point measurement to a multi-point spatial measurement by arranging photodetectors in a two-dimensional array. This dimensional expansion allows the system to capture spatial information about user contact location and movement, improving the ability to accurately measure biometrics during dynamic user interactions
2Reliability
If multiple light sources and additional hardware like accelerometers are added, then the reliability of biometric detection improves, but the device complexity and costs increase
Solution Approach 1:
The photodetector array serves multiple functions simultaneously: it detects touch events, tracks user movement, and captures biometric data all using the same hardware component. This multi-functionality eliminates the need for separate accelerometers and multiple light sources, achieving reliable biometric detection while keeping device complexity and costs manageable
Solution Approach 2:
The system uses the photodetector array's own spatial and temporal information to infer user movement and contact characteristics without requiring external sensors. The array self-provides the data needed for reliable biometric detection by analyzing which photodetectors are activated and when, eliminating dependency on additional hardware
3Productivity
If proactive user actions are required for biometric measurement, then the ease of operation improves, but the productivity and continuous monitoring capability are reduced
Solution Approach 1:
The photodetector array continuously monitors for touch events and biometric signals without requiring explicit user initiation. The system maintains continuous readiness to capture biometric data whenever contact occurs, enabling uninterrupted monitoring during normal user interactions while automatically triggering measurements without requiring users to perform specific actions
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 improves the accuracy and reliability of biometric data collection, reduces costs by eliminating the need for additional hardware, and allows for biometric data to be collected during normal user interactions without specific requests for measurement.
Implementation Method 1
a photodetector array including a plurality of photodetectors that is coupled to the body and configured to detect light of the light source reflected from the user
Implementation Method 2
a photodetector array including a plurality of photodetectors that is coupled to the body and configured to detect light of the light source reflected from the user
Data Source
AI summary
A computing device, such as a wearable device, may include a light source and a photodetector array. The photodetector array may be used to determine a touch event of a user that occurs during a time interval. A subset of the plurality of photodetectors associated with the touch event may provide detection signals at each of a plurality of times within the time interval, which may be aggregated to obtain a time series of aggregated detection signals. Biometric data of the user may be generated, based on the time series of aggregated detection signals.