Wrist-Worn Medical Alert Device Using PPG Finger Movement Detection
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Solution Overview
Problem
Existing medical alert systems are inadequate for users who cannot operate conventional devices due to immobilization or dizziness, and they often result in delayed assistance, with vital sign-based systems covering only limited emergency situations and risking false alarms.
Innovation Solution
A wrist-worn medical alert device using photoplethysmography (PPG) to detect finger movements and transmit emergency messages, allowing users to activate alerts with minimal effort and in various positions, combining with existing vital sign monitoring devices to enhance robustness and reduce false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manual alert button is used, then the user can activate the alarm when conscious and mobile, but the user cannot activate the alarm when immobilized or experiencing dizziness
Solution Approach 1:
The system performs automatic fall detection and alarm activation without requiring user intervention. The processing unit continuously monitors sensor data (accelerometer, gyroscope, barometer) to detect fall patterns and automatically triggers the alarm, enabling the system to serve itself in emergency situations where the user cannot activate it manually.
Solution Approach 2:
The patent replaces the mechanical action of pressing a button with automated sensor-based detection. Instead of requiring physical interaction with a button, the system uses accelerometers, gyroscopes, and barometers to detect falls and triggers alarms automatically, substituting mechanical operation with electronic sensing and processing.
2Extent of automation
If passive systems with predetermined time thresholds are used, then the alarm can be triggered automatically, but a significant amount of time elapses before assistance is provided
Solution Approach 1:
The system performs preliminary actions by continuously monitoring vital signs and environmental sensors before an emergency occurs. When a fall is detected, the system has already been collecting relevant data (heart rate, oxygen saturation, location) and can immediately process and transmit this information, eliminating delays associated with post-fall assessment.
Solution Approach 2:
The system implements feedback loops where sensor data is continuously analyzed and compared against fall detection algorithms. When a fall pattern is detected, the system immediately provides feedback by triggering the alarm and notifying emergency contacts, creating a rapid response cycle that minimizes time loss.
3Extent of automation
If vital sign-based monitoring systems are used, then automatic alarm triggering is possible, but the systems risk triggering false alarms and cover only limited emergency situations
Solution Approach 1:
The patent merges multiple detection methods including fall detection algorithms, vital sign monitoring, and environmental sensor data. By combining these diverse sensing modalities, the system cross-validates emergency conditions, ensuring that alarms are triggered only when multiple sensors confirm a genuine emergency, thereby reducing false alarms while expanding coverage.
Solution Approach 2:
The system is designed with multi-functionality to detect various emergency situations beyond just falls, including medical emergencies detected through vital sign anomalies. The integrated sensor suite and processing unit can recognize multiple types of emergencies, making the system universally applicable while maintaining reliability through pattern recognition across different sensor data types.
4Device complexity
If conventional alarm devices are used, then the system structure is simple, but the device cannot be operated when the user is immobilized
Solution Approach 1:
The patent replaces mechanical operation (button pressing) with automated electronic sensing using accelerometers, gyroscopes, and barometers. The system detects falls through motion pattern recognition and automatically triggers alarms, eliminating the need for mechanical user interaction while maintaining relatively simple device structure through integration of these sensors.
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
Enables users to trigger alerts more easily and accurately in a wider range of emergency situations, reducing the time to receive assistance and minimizing false alarms, while leveraging existing PPG technology for both vital sign monitoring and user-activated alerts.
Implementation Method 1
a PPG (photoplethysmography) unit adapted to acquire a first PPG signal at first wavelength (λ1) and a second PPG signal at second wavelength (λ2) over time at the wrist of the subject
Data Source
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AI summary
The present invention relates to the field of medical emergency signaling and user-activated medical alarm systems. In particular, a wrist-worn medical alert device (10) for conveying an emergency message to a caregiver (80) is presented, wherein the medical alert device is adapted to be worn at a wrist (101) of a subject (100), the device comprising: a PPG unit (20) adapted to acquire a first PPG signal (26) at first wavelength (λ1) and a second PPG signal (25) at second wavelength (λ2) over time at the wrist of the subject; a processing unit (30) adapted to receive the first and second PPG signals (25, 26) and to determine a finger movement of one or more fingers (102) of the subject (100) based on the first and second PPG signals; and a communication unit (40) adapted to transmit, based on the determined finger movement, an emergency message to the caregiver (80). The present invention further relates to a corresponding system (1), method (60) and computer program for carrying out said method.