The next generation of wearable electronics could soon become more comfortable, flexible and energy independent. Scientists are developing a new type of power-generating textile that can harvest energy from two sources that are always around us: sunlight and mechanical movement.
In a recent development, Chen and his research team have created a micro-cable power textile that combines lightweight solar cells with fibre-based triboelectric nanogenerators. The result is a flexible smart fabric capable of converting both solar energy and everyday mechanical motion into electrical power.
The technology could eventually be incorporated into clothing, curtains, tents and other fabric-based products, providing an entirely new approach to powering wearable electronics.
The Challenge of Powering Wearable Electronics
Wearable technologies are becoming increasingly common. Smartwatches, health-monitoring devices, sensors and other electronic systems can collect useful information while being worn on the body.
However, all these devices need electricity.
Traditional batteries provide reliable power, but they add weight, occupy space and eventually need to be recharged or replaced. For future wearable electronics, researchers therefore want power sources that are lightweight, flexible, portable and easy to integrate into everyday objects.
Ideally, such a power source should also generate electricity without requiring a conventional charging system.
This is where energy-harvesting textiles could make a major difference.
Instead of carrying a separate battery or solar panel, the fabric itself could produce electricity while a person moves or while sunlight falls on the material.
A Fabric That Harvests Two Types of Energy
The new power textile takes advantage of two different energy-generation technologies.
The first is solar energy harvesting. The researchers fabricated solar cells using lightweight polymer fibres and transformed them into tiny cable-like structures known as micro cables.
These solar-cell micro cables can capture energy from sunlight while remaining flexible enough to be incorporated into textile structures.
The second technology is the triboelectric nanogenerator, or TENG.
Triboelectric nanogenerators generate electricity through contact and separation between different materials. When materials repeatedly touch, separate, bend, stretch or experience friction, electrical charges can develop. These charges can then be collected to produce useful electrical energy.
Everyday movements provide plenty of mechanical energy that would otherwise be wasted.
Walking, running, waving an arm, moving fabric in the wind or even the movement of a curtain can potentially provide mechanical excitation for a triboelectric generator.
By combining solar cells and triboelectric generators into one textile, the researchers created a system capable of harvesting energy from both sunlight and movement at the same time.
Turning Energy-Producing Fibres Into Fabric
Creating an energy-generating fibre is only part of the challenge. Researchers also need to transform these fibres into practical fabrics without making them too thick, heavy or uncomfortable.
Chen and his team addressed this problem by weaving the solar-cell micro cables together with fibre-based triboelectric nanogenerators.
The researchers used a shuttle-flying weaving process to construct the smart fabric.
The resulting textile was remarkably thin. A single layer was approximately 320 micrometres thick, making it suitable for integration into a range of fabric-based products.
Because the energy-generating components are built into the textile itself, the technology does not necessarily require a large, rigid solar panel or bulky mechanical generator.
This could allow energy harvesting to become part of the fabric rather than an additional device attached to it.
How Much Energy Can It Generate?
To demonstrate the capabilities of their technology, the researchers produced a hybrid power textile measuring approximately 4 × 5 centimetres.
The small textile was tested under ambient sunlight while mechanical excitation was also present.
The researchers demonstrated that the fabric could charge a 2-millifarad commercial capacitor to 2 volts in just one minute.
Importantly, the mechanical excitation did not have to come from a complicated machine. Sources such as human movement and wind could provide the mechanical input needed by the triboelectric component.
This demonstrates the potential of combining naturally available energy sources.
During the day, sunlight could provide one source of electricity, while movement or wind could provide another. Instead of relying entirely on one energy source, the textile can take advantage of whatever energy is available in its surroundings.
More Than Just a Laboratory Demonstration
One of the most interesting aspects of the technology is that the researchers demonstrated practical applications rather than simply measuring electrical output.
The power textile was able to continuously operate an electronic watch.
The researchers also demonstrated that it could directly charge a cell phone and drive water-splitting reactions.
These demonstrations show that energy-generating textiles could potentially move beyond powering very small sensors and become useful for a wider range of low-power electronic applications.
However, practical commercial products would still require further development. Devices such as smartphones have relatively high energy demands compared with small wearable sensors, so the amount of power produced by a textile will depend on factors such as its size, sunlight intensity and mechanical activity.
Potential Applications
The flexibility of the textile opens up many possibilities.
Smart Clothing
Clothing incorporating these power-generating fibres could potentially harvest energy while people walk or move. This electricity could support wearable sensors, health-monitoring devices or other low-power electronics.
Self-Powered Outdoor Equipment
The technology could also be integrated into tents, backpacks and outdoor fabrics. Sunlight and wind are naturally available in many outdoor environments, making them useful energy sources.
Energy-Generating Curtains
Curtains could potentially harvest sunlight through their solar components while simultaneously generating electricity from movement caused by airflow.
Future Wearable Sensors
As wearable sensors become smaller and more widespread, continuously supplying them with power will become increasingly important. Energy-harvesting fabrics could help reduce dependence on conventional batteries.
A Step Toward Sustainable Wearable Electronics
The importance of this technology goes beyond simply generating electricity.
Future electronics will increasingly need power sources that are lightweight, flexible, durable and easy to integrate into everyday environments.
A conventional battery is designed to store energy, but it does not continuously harvest energy from the surroundings. A smart power textile takes a different approach: it turns an everyday material into an active energy-generating system.
The combination of solar and mechanical energy harvesting is particularly promising because the two sources can complement each other. Sunlight is available during suitable daytime conditions, while mechanical energy can be generated through human activity or environmental movement.
The Future of Power Could Be Woven Into Our Clothes
The research by Chen and his team demonstrates an intriguing vision for future electronics: instead of attaching a power source to our clothes, the clothes themselves could become the power source.
By integrating flexible solar-cell micro cables and triboelectric nanogenerators into a thin textile, the researchers have shown that ordinary-looking fabric can potentially perform an important electronic function—harvesting energy from its surroundings.
Although challenges such as increasing power output, improving durability, manufacturing at large scale and integrating the technology with commercial electronics remain, the concept represents an important step toward self-powered wearable technology.
In the future, the fabric covering our bodies, homes and outdoor equipment may do more than provide protection and comfort. It could quietly collect energy from sunlight, movement and wind—and use that energy to keep the next generation of electronics running.
Reference: Chen, J., Huang, Y., Zhang, N. et al. Micro-cable structured textile for simultaneously harvesting solar and mechanical energy. Nat Energy 1, 16138 (2016). https://doi.org/10.1038/nenergy.2016.138
Comments
Post a Comment