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Innovation in wearable textiles exploit potential of human body to generate electricity

M A Mohiemen Tanim June 14, 2023Last Updated: June 14, 2023

0 8 minutes read

Figure 1: Application outlook and schematic diagram of the self-charging power textile. (a) Application prospects of the self-charging power textile containing energy harvesting, management, and storing units for wearable electronics. (b) Scheme diagram of the self-charging power textile. (c) Photograph of the fabricated self-charging power textile into a cloth. (d) Schematic diagram of the coaxial fiber-TENG. (e) Schematic diagram of the fiber-SC

In this world, The use of electronic devices is increasingly popular. And so, the demand graph for efficient and sustainable power sources is uprising. In recent times, wearable technologies gained significant popularity, and researchers continuously working to explore innovations in this area.

Recently, there was a journal published with the title “Wearable energy harvesting-storage hybrid textiles as on-body self-charging power systems” by Nano Research Energy. This journal describes a breakthrough solution that comes in the form of wearable energy harvesting-storage hybrid textiles, capable of harnessing energy from the environment and seamlessly integrating it into the fabric of our clothing.

Harnessing Energy from the Environment

The research study, conducted by a team of scientists from leading institutions in China and the USA, focuses on developing textiles that can capture energy from the surrounding environment. These textiles incorporate various energy-harvesting technologies, including piezoelectric, thermoelectric, and photovoltaic mechanisms. By capitalizing on the wearer’s movements, body heat, and exposure to light, these textiles convert ambient energy into usable electrical power.

How to develop fiber-TENG & Technologies behind it

Firstly, a coaxial fiber-shaped structure is created using materials such as polylactic acid (PLA), reduced graphene oxide (rGO), and polypyrrole (PPy). This structure forms the basis of the triboelectric nanogenerator (TENG), which is responsible for harvesting energy from low-frequency and irregular human motion.

To enhance energy storage capabilities, a coaxial fiber-shaped supercapacitor (SC) is integrated into the textile. This is achieved by loading a wet-spun graphene oxide fiber with functionalized materials. The SC acts as an efficient energy storage unit, capable of storing and delivering power when needed.

***Figure 2***: Structure characterization of the fiber-SC. (a) Schematic diagram of the preparation process of the fiber-SC. SEM images of a bare GO fiber (b), the knotting of GO fiber (c), a bare rGO fiber (d), the cross-section of GO fiber (e), a rGO fiber coated with MnO2 (f), a rGO-MnO2 fiber coated with PPy (g), a rGO-MnO2-PPy fiber coated with PVA/H3PO4 (h), a rGO-MnO2-PPy-PVA/H3PO4 fiber coated with MWNCTs (i), cross-section of the fiber-SC (j).

The next step in the development process is to ensure the flexibility and adaptability of the textile. This is achieved through careful engineering and design considerations. The textile is made flexible and knitted, allowing it to seamlessly integrate into various wearable garments without compromising comfort or mobility.

The textile is designed to be wearable, meaning it can be comfortably worn on the body. This enables users to harness the energy generated by their movements and activities, turning their bodies into a self-charging power sources. The integration of the textile with portable electronics further enhances its practicality and usability.

Piezoelectric Effect

One of the key methods employed in these hybrid textiles is the piezoelectric effect. By embedding tiny piezoelectric fibers or nanogenerators within the fabric, mechanical stress and vibrations generated during body movements can be converted into electrical energy. These fibers can be woven or integrated into the textile structure without compromising comfort or flexibility, making them ideal for wearable applications.

The piezoelectric effect relies on the unique properties of certain materials, such as zinc oxide or lead zirconate titanate (PZT), which generate an electric charge in response to mechanical pressure or deformation. When incorporated into the fabric, these piezoelectric materials act as sensors that convert kinetic energy, produced by movements like walking or arm swinging, into electrical energy.

Research in this area has shown promising results. For example, a simple walking motion can generate sufficient energy to power low-power sensors or wearable devices, such as fitness trackers or medical monitoring devices. This capability eliminates the need for frequent battery replacements and reduces environmental waste.

**Figure 3:** Schematic diagram and electric performance of the fiber-TENG. (a) The preparation mechanism of the fiber-TENG. Inserts: SEM images of a bare PLA fiber; the PLA-GO fiber; the PLA-rGO fiber; the PLA-rGO coated with PPy; scale bar: 100 μm. (b) VOC (c) ISC (d) QSC of fiber-TENG under different working frequencies (1–5 Hz) with force load at 13 N. (e) The relationship between current and power density and external load resistance with an external load resistance from 104 to 7×109 Ω (at 1 Hz). (f) The charging voltage curves of different commercial capacitors by the fiber-TENG. (g) ISC of fiber-TENG that continuously operates for ~ 30,000 cycles (at 1 Hz).

Thermoelectric Conversion

The researchers also explored the integration of thermoelectric materials into textile design. By utilizing the temperature difference between the body and the ambient environment, these materials can generate electricity through the Seebeck effect. The integration of flexible and lightweight thermoelectric modules within the textile enables efficient energy harvesting and storage while maintaining comfort and wearability.

The Seebeck effect is based on the principle that a temperature gradient across a junction of two materials can generate an electric voltage. In the context of wearable textiles, thermoelectric materials, such as bismuth telluride or lead telluride, can convert the temperature difference between the wearer’s body and the surrounding environment into usable electrical power.

This technology opens up new avenues for on-body self-charging power systems. By harnessing body heat, which is constantly produced and wasted, these textiles can generate electricity without requiring any additional external energy input. This capability is precious in cold climates or during physical activities when body heat generation is at its peak.

Photovoltaic Technology

Incorporating photovoltaic cells into wearable textiles opens up new possibilities for harvesting energy from light. Thin, flexible, and lightweight solar cells can be integrated seamlessly into the fabric, allowing them to absorb solar radiation and convert it into electricity. This advancement paves the way for a self-charging power system that operates efficiently even in indoor environments with limited exposure to natural light.

Photovoltaic cells, often made of silicon or other semiconducting materials, absorb photons from sunlight and release electrons, which then flow as an electric current. The integration of these cells within textiles requires specialized techniques to ensure flexibility and durability. Researchers have made significant progress in developing efficient solar textiles that can withstand bending, stretching, and washing while maintaining high energy conversion efficiency.

By leveraging the photovoltaic capabilities of these textiles, wearable devices can continuously charge their batteries during everyday activities. This eliminates the need for frequent external charging, enhances user convenience, and extends device usage time.

Advancements in Energy Storage

While energy harvesting is a crucial aspect of wearable energy textiles, efficient energy storage is equally essential. The research study explores different storage options, including flexible batteries and supercapacitors, to store and release harvested energy effectively.

Flexible batteries, often based on thin-film lithium-ion technology, can be integrated into the textile structure or attached as separate components. These batteries provide a reliable and compact energy storage solution that can withstand the flexing and bending associated with wearable applications.

Supercapacitors, on the other hand, offer rapid energy storage and release capabilities. With their high power density and long cycle life, supercapacitors are well-suited for meeting the dynamic energy demands of wearable devices. Researchers are actively exploring methods to integrate supercapacitors directly into the textile fibers, creating hybrid textiles that combine energy harvesting, storage, and delivery in a single, unified system.

How this technology makes a change

The integration of these advanced energy storage technologies within wearable textiles ensures that the harvested energy is efficiently stored and available when needed. This capability addresses the intermittent nature of energy harvesting and provides a reliable power source for wearable devices.

Integration and practical applications

The successful integration of energy harvesting and storage technologies within textiles opens up many practical applications. Wearable energy harvesting-storage hybrid fabrics have the potential to transform various industries and enhance the functionality of wearable devices.

Healthcare and fitness

In healthcare, these textiles can power medical monitoring devices, such as continuous glucose or heart rate monitors. Patients can benefit from constant, hassle-free monitoring without frequent battery replacements. Fitness enthusiasts can also take advantage of these textiles to power their fitness trackers, smartwatches, or wireless headphones, ensuring uninterrupted tracking and data collection during workouts.

Military and first responders

Wearable energy textiles have significant implications for military personnel and first responders. Soldiers in the field can utilize these textiles to power communication devices, GPS systems, and body sensors, reducing their reliance on external power sources and enhancing mobility. Similarly, firefighters and emergency responders can benefit from self-charging power systems integrated into their protective clothing, enabling them to focus on critical tasks without worrying about battery life.

Fashion and smart clothing

The fashion industry can embrace wearable energy textiles to create innovative and functional bright clothing. By seamlessly integrating energy harvesting and storage capabilities, designers can develop clothing items that power embedded LEDs, heating elements, or even small displays. This fusion of fashion and technology not only adds aesthetic value but also enhances the practicality and versatility of clothing.

Internet of Things (IoT)

The proliferation of IoT devices calls for efficient and sustainable power solutions. Wearable energy harvesting-storage hybrid textiles can be a reliable power source for many IoT devices. From smart home sensors to industrial monitoring systems, these textiles can provide continuous and autonomous power, eliminating the need for frequent battery changes or cumbersome wired connections.

Challenges and Future Directions

While the research on wearable energy harvesting-storage hybrid textiles has shown remarkable progress, several challenges remain to be addressed before widespread adoption and commercialization.

Efficiency optimization

Researchers continue to explore ways to improve the energy conversion efficiency of these textiles. Enhancements in material selection, design optimization, and integration techniques are crucial to maximizing energy harvesting and storage capabilities. Increasing efficiency ensures that these textiles can generate and store sufficient power to meet the demands of various wearable devices.

Durability and washability

Textiles are subject to rigorous use and frequent washing, requiring wearable energy textiles to withstand these conditions. Developing robust and washable materials, as well as reliable encapsulation techniques, is essential to maintain the functionality and longevity of these textiles. Users should be able to wear and maintain these garments without compromising their energy-harvesting capabilities.

Scalability and manufacturing

For widespread adoption, wearable energy textiles must be scalable and cost-effective to manufacture. Researchers and industry partners are working together to develop scalable manufacturing processes that can integrate energy-harvesting and storage technologies into textile production lines. This approach will facilitate mass production and make these textiles more accessible to consumers.

User acceptance and comfort

User acceptance and comfort are vital factors for the successful adoption of wearable technologies. It is crucial to balance functionality, aesthetics, and comfort when designing these textiles. Ensuring that they are lightweight, breathable, and conform to the body’s movements will contribute to user satisfaction and encourage long-term usage.

Wearable energy harvesting-storage hybrid textiles represent a significant leap forward in the realm of wearable technology. The integration of energy harvesting and storage capabilities within textiles offers a sustainable solution to the power limitations of wearable devices.

With their potential applications in healthcare, military, fashion, and IoT, these textiles have the power to revolutionize multiple industries. While challenges remain, ongoing research and collaborative efforts are driving progress toward efficient, durable, and commercially viable wearable energy textiles. The future holds exciting possibilities for wearable self-charging power systems, empowering individuals, and transforming the way we interact with technology.

For More Information: Sheng F, Zhang B, Cheng R, et al. Wearable energy harvesting-storage hybrid textiles as on-body self-charging power systems. Nano Research Energy, 2023, https://doi.org/10.26599/NRE.2023.9120079