Wearable Optical Sensor Control Using Skin Contact Reliability
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Solution Overview
Problem
Optical sensors for heart rate and oxygen monitoring require constant skin contact for accurate measurements but often lose contact due to user movement, leading to inaccurate readings and high power consumption.
Innovation Solution
Incorporating an electrostatic charge sensor with a receiving and ground electrode to detect skin contact, generating a contact reliability index (CRI) to adjust optical sensor operation based on contact level, thereby ensuring accurate measurements and optimizing power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical sensors continuously obtain measurements, then measurement availability is improved, but power consumption increases
Solution Approach 1:
The optical sensor operates intermittently rather than continuously, performing measurements at periodic intervals or only when triggered by specific conditions (such as detected skin contact). This periodic operation reduces overall power consumption while maintaining measurement availability when needed.
Solution Approach 2:
The system uses feedback from the electrostatic charge sensor to control the optical sensor operation. When the electrostatic charge sensor detects skin contact, it triggers the optical sensor to take measurements. This feedback-based control ensures measurements are only taken when reliable contact exists, improving measurement availability without continuous operation.
2Use of energy by moving object
If optical sensors operate intermittently to save power, then power consumption is reduced, but measurement accuracy deteriorates due to lost contact detection
Solution Approach 1:
The electrostatic charge sensor performs preliminary detection of skin contact before the optical sensor takes measurements. This preliminary action ensures that the optical sensor only operates when reliable contact is confirmed, preventing inaccurate measurements while maintaining power efficiency.
Solution Approach 2:
The electrostatic charge sensor acts as an intermediary between the user's skin and the optical sensor. It provides preliminary verification of contact conditions, ensuring that the optical sensor only measures when proper contact exists, thus maintaining measurement accuracy without continuous operation.
3Ease of operation
If users wear watches loosely for comfort, then ease of operation is improved, but measurement reliability deteriorates due to gap between sensor and skin
Solution Approach 1:
The system provides feedback about contact quality through the CRI (Contact Quality Indicator). When the electrostatic charge sensor detects weak contact (indicating the watch is worn loosely), the system can alert the user to adjust the fit or indicate that measurements may be unreliable, allowing users to maintain comfort while being aware of measurement quality.
Solution Approach 2:
The system changes the operational parameters of the optical sensor based on contact quality. When weak contact is detected, the system may adjust measurement thresholds, increase sampling frequency, or modify processing algorithms to compensate for the reduced contact quality, maintaining measurement reliability despite loose wearing.
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
Ensures accurate optical sensor readings by maintaining skin contact detection and conserves power by adjusting sensor operation based on contact reliability, reducing power consumption when contact is lost.
Implementation Method 1
the device detects whether or not the optical sensors are in physical contact with the user's skin using an electrostatic charge sensor, a receiving electrode electrically coupled to the electrostatic charge sensor, and a ground electrode electrically coupled to ground
Data Source
AI summary
The present disclosure is directed to a wearable electronic device, such as a watch, that includes one or more optical sensors. In order to determine accuracy of measurements by the optical sensors, the device detects whether or not the optical sensors are in physical contact with the user's skin. The device detects a level of contact between the user's skin and the optical sensors based on electrostatic charge variation measurements, and generates a contact reliability index (CRI) based on the level of contact. Operation of the optical sensors are adjusted based on the CRI.