Sweat-Powered Bluetooth Backscatter Wearable for Battery-Free Sensing
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Solution Overview
Problem
Typical health monitoring sensor systems have high power requirements, leading to poor wireless communication range and the need for physical connections that interfere with practical use.
Innovation Solution
A self-powered backscatter sensing system using a sweat-activated cell to power a wearable sensor device that modulates antenna impedance to reflect sensor data via Bluetooth, eliminating the need for batteries and relying on a smartphone's power source for continuous wave signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional health monitoring sensor systems are used, then wireless communication capability is provided, but power consumption is high requiring frequent battery replacement or charging
Solution Approach 1:
The sensor system harvests energy from the user's body movements and environmental conditions to power itself, eliminating the need for external battery replacement or charging. The energy harvesting circuit converts mechanical energy from body motion into electrical energy to sustain sensor operation and wireless communication.
Solution Approach 2:
The patent replaces the traditional battery-based electrical power system with an energy harvesting system that converts mechanical energy from body movements into electrical energy, fundamentally changing how the device is powered and enabling truly wireless, maintenance-free operation.
2Duration of action of moving object
If battery size is increased to extend operation duration, then continuous monitoring capability is improved, but device size and weight increase
Solution Approach 1:
Instead of carrying larger batteries to extend operation duration, the device harvests energy continuously from the user's body movements and environment, providing unlimited operation without increasing device weight. The energy harvesting components are minimal in mass compared to large-capacity batteries.
Solution Approach 2:
The energy harvesting system operates continuously by capturing periodic mechanical energy from body movements, converting them into electrical energy to power the device. This periodic energy capture replaces the need for large energy storage components.
3Length of moving object
If wireless communication range is extended, then data transmission capability is improved, but power consumption increases
Solution Approach 1:
The patent employs energy harvesting from body movements to provide the additional power needed for extended wireless communication range. The mechanical energy captured during natural movement compensates for the increased power consumption of high-range wireless transmission.
Solution Approach 2:
The system dynamically adjusts communication parameters such as transmission power and data rate based on available harvested energy and communication needs, optimizing the balance between communication range and power consumption to maintain extended range while managing energy usage efficiently.
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 low-power, maintenance-free wireless health monitoring with a theoretically infinite shelf life, utilizing backscatter communication to transmit data directly to a smartphone without infrastructure, suitable for short-term health monitoring and emergency situations.
Implementation Method 1
powered by a sweat- or self-activated cell (SAC) ('sweat battery')
Implementation Method 2
A self-powered backscatter sensing system using a sweat-activated cell to power a wearable sensor device that modulates antenna impedance to reflect sensor data via Bluetooth
Data Source
AI summary
The present disclosure presents self-powered Bluetooth backscatter sensor systems and related methods. One such system comprises a wearable sensor device having communication circuitry, sensor circuitry, and at least one sweat-activated cell for powering the sensor circuitry; and a transmitter device having an interface for receiving power supplied from a power interface of an electronic communication device having a communication receiver. The transmitter device is configured to be powered by the electronic communication device via the power interface and transmit a continuous wave signal, such that the communication circuitry is configured to receive the continuous wave signal. The sensor circuitry is configured to acquire sensor data; and the communication circuitry is configured to modulate the sensor data onto the received continuous wave signal and transmit the modulated signal as a backscattered signal. Accordingly, the communication receiver is configured to receive the transmitted backscattered signal having the modulated sensor data.