Self-powered wearable for continuous biometrics monitoring
A user-wearable device utilizes energy harvesting technology to lengthen battery life or eliminates the need to charge the wearable device. In one embodiment, a user-wearable device combines energy harvesting technology with low power sensors and high efficiency processing methods to realize a self-charging or battery-less biometric monitoring system. The wearable biometric monitoring system provides accurate biometric measurements while enhancing user experience by extending the battery life or completely eliminating the need for the user to charge the device.
1. A user-wearable device for biometric measurement of a user, comprising:
an energy harvester;
an energy storage coupled to the energy harvester to store energy harvested by the energy harvester; and
components configured to consume the energy stored in the energy storage, the components including:
a sensor configured to measure at least one biological signal of the user, the sensor configured to receive power from the energy storage; and
a processor configured to process the biological signal measured by the sensor, the processor configured to receive power from the energy storage,
wherein the sensor and the processor are configured to be controlled by an adaptive power controller that is configured to adjust a sensing duty cycle schedule of the sensor and a signal process time of the processor based on an energy expenditure pattern of the user and an activity level of the user to realize power balance between the energy generation by the energy harvester and energy consumption by the components configured to consume the energy stored in the energy storage.
2. The user-wearable device of claim 1 , wherein the sensor is selected from one of a low power inertial measurement sensor, a photoplethysmogram (PPG) sensor, a microelectromechanical systems (MEMS) sensor, an electrocardiogram (ECG) sensor, a bioimpedence sensor, a galvanic skin response (GSR) sensor, and a piezoelectric sensor.
3. The user-wearable device of claim 2 , wherein the sensor in the sensor is configured to measure at least one biological signal of the user, and wherein the biological signal is selected from resting heart rate, respiration rate, activity energy expenditure, sleep monitoring, and snoring detection.
4. The user-wearable device of claim 2 , wherein the low power inertial measurement sensor comprises an accelerometer.
5. The user-wearable device of claim 1 , wherein the adaptive power controller is configured to adjust the sensing duty cycle schedule and the signal process time so that the power consumed by the sensing operation of the sensor and the signal processing operation of the processor is equal to or less than the power generated by the energy harvester.
6. The user-wearable device of claim 1 , wherein the adaptive power controller is configured to adjust the sensing duty cycle schedule and the signal process time so that, over a first time period, the sum of the energy harvested by the energy harvester and the energy stored in the energy storage is equal to or greater than the sum of the energy consumed by performing the sensing operation and the signal processing operation during a first duty cycle and the energy consumed during an inactive mode outside of the first duty cycle.
7. The user-wearable device of claim 1 , wherein the energy harvester comprises a thermoelectric generator arranged to measure the temperature difference between a body temperature of the user and the environment external to the user and to generate a voltage proportional to the temperature difference.
8. The user-wearable device of claim 1 , wherein the energy harvester comprises one of a kinetic energy harvester, radio frequency (RF) energy harvester, piezoelectric energy generator, solar power generator, ambient vibration-powered energy harvester, photovoltaic energy generator, and electrodynamic power generator.
9. The user-wearable device of claim 1 , wherein the energy storage comprises a rechargeable battery or a capacitor.
10. The user-wearable device of claim 1 , wherein the power consumed by the sensor operation and the signal processing operation is supplied by the energy harvester only.
11. The user-wearable device of claim 1 , wherein the components include a plurality of sensors, and the adaptive power controller selects the sensor from the plurality of sensors to realize power balance between the energy generation and the energy consumption.
12. The user-wearable device of claim 1 , wherein the user-wearable device includes the adaptive power controller.