A thermoelectric wearable ambient energy harvester is a device designed to capture and convert ambient heat into usable electrical energy through the principle of thermoelectric effect. This technology takes advantage of the temperature difference between the wearer's body and the surrounding environment to generate power that can be used to charge small electronic devices or power sensors.
The working principle of a thermoelectric wearable ambient energy harvester can be broken down into several key steps:
Thermoelectric Materials: The heart of the device lies in the use of special materials known as thermoelectric materials. These materials exhibit the thermoelectric effect, which is the ability to generate a voltage difference (and thus an electric current) when there is a temperature gradient across the material.
Temperature Difference: In a wearable energy harvester, there is a significant temperature difference between the surface of the device in contact with the wearer's body and the surrounding environment. The body heat of the wearer warms one side of the device, while the other side remains cooler due to the ambient temperature.
Thermoelectric Modules: The device consists of multiple thermoelectric modules, also known as thermoelectric couples or junctions. Each module is typically made up of two different types of thermoelectric materials, one with high thermoelectric efficiency for the hot side and another with low thermoelectric efficiency for the cold side.
Thermal Gradient: As heat flows from the wearer's body to the ambient environment, it crosses the thermoelectric modules. This thermal gradient across the modules creates a voltage difference due to the thermoelectric effect, generating an electric current. The generated electrical energy is then collected from the thermoelectric modules.
Power Generation and Management: The generated electrical energy is usually in the form of a low voltage and low current output. This energy is then passed through power management circuitry, which may include voltage converters, regulators, and energy storage components (like capacitors or batteries). These components ensure that the harvested energy is appropriately conditioned and stored for use by electronic devices or sensors.
Wearable Integration: The device is designed to be wearable, often taking the form of patches, bands, or other wearable accessories. This ensures effective contact between the thermoelectric materials and the wearer's skin to optimize the heat transfer and energy harvesting process.
It's important to note that the efficiency of thermoelectric energy harvesting is currently limited, and significant temperature differences are required to generate a meaningful amount of power. As a result, thermoelectric wearables are typically more suited for situations where there is a substantial temperature gradient, such as outdoor activities or environments with significant temperature variations.
Overall, the thermoelectric wearable ambient energy harvester serves as an innovative solution to harness a portion of the otherwise wasted heat energy from the human body and the surrounding environment, contributing to the development of self-sustaining and energy-efficient wearable electronic devices.