A research team from Queensland University of Technology (QUT) has developed a flexible and extremely thin film to power wearable devices using just our body heat, hence eliminating the need for batteries.
The new technology could also be used to cool electronic chips in smartphones and computers, as such, helping them run more efficiently as well as enhancing their stability.
The breakthrough, according to Professor Zhi-Gang Chen, the founding director of the ARC Research Hub in Zero-emission Power Generation for Carbon Neutrality (ZeroPC), addresses a key challenge in creating a thermoelectric device that converts body heat into power. The device has the potential to be a sustainable energy source for wearable electronics.
Talking about flexible thermoelectric devices, Professor Chen explained that:
“They can be worn comfortably on the skin where they effectively turn the temperature difference between the human body and surrounding air into electricity.”
Building an Exceptional Thermoelectric Wearable Device
Devices that can convert body heat into energy, while a topic of immense interest and exploration, currently face the challenge of high costs, complex manufacturing, limited flexibility, and insufficient performance, preventing its mass production and adoption.
Source: Queensland University of Technology
In the latest study published in the journal Science, the QUT team introduced a cost-effective method for creating flexible thermoelectric films. For this, they used tiny crystals or ‘nanobinders’ that form a consistent layer of bismuth telluride sheets, boosting both flexibility and efficiency.
Bismuth telluride (Bi2Te3) is a popular material used by researchers to build such devices. The gray powder is a compound of bismuth and tellurium. The chemically stable semiconductor showcases excellent properties that convert heat into electricity, making it ideal for low-power applications like movement, heart rate, and temperature monitors.
So, the QUT team created a printable film of A4 size “with record-high thermoelectric performance, exceptional flexibility, scalability, and low cost, making it one of the best flexible thermoelectrics available,” said Professor Chen.
The printable film from the QUT team comprises Bi2Te3-based nanoplates as highly orientated grains and Te nanorods as “nanobinders.”
The technique used here was “solvothermal synthesis,” which forms nanocrystals in a solvent under high temperature and pressure. This technique was combined with “sintering,” which heats the films to near-melting point to bond the particles together, and “screen-printing,” which enables large-scale film production.
The method used by the team could also work with other inorganic systems like silver selenide (Ag2Se)-based thermoelectrics, which are potentially cheaper and more sustainable than conventional materials, showing the technique’s broad applicability.
“This flexibility in materials shows the wide-ranging possibilities our approach offers for advancing flexible thermoelectric technology.”
– The study’s first author, Wenyi Chen
The device, as per the study, attained a normalized power density of >3 μW cm−2 K−2, which the team states is “ranking among the highest in screen-printed devices.”
With that, the latest research offers a powerful solution for wearables like smartwatches and personal thermal management. In addition to powering up the wearables, these thermoelectric devices can also be applied in a tight space, such as the inside of a mobile phone, to help cool chips and improve performance.
For instance, when applied inside a device, the film can bring down the chip temperature by up to 11.7 Kelvin, as such, helping maintain optimal performance in electronic devices.
If the team successfully improves the performance of this flexible electric device, they’ll be able to power directly for smartphones of the future, stated Chen in the official video titled, “Breakthrough brings body-heat powered wearable devices closer to reality,” posted on the University’s YouTube channel.
Other potential applications of the device include air conditioning systems and ventilation. The QUT research team also envisions the use of thermoelectric devices in smart clothing and automotive components.
This is just the beginning, though; in the next step, the team will focus on optimizing the technology’s performance and scaling it. Taking the tech commercial, after all, requires overcoming the challenges of cost-efficiency at scale, durability, and integration with existing devices.
Further research and continued development will help these devices revolutionize energy efficiency in various sectors, from consumer electronics to medical and automotive applications.
Click here to learn how health wearables are advancing preventive care.
Advances in Wearables Technology
In today’s technologically advanced world, wearable devices have emerged as a popular and highly beneficial innovation.
Wearables are simply mobile electronic devices that are designed to be worn on the body or attached to clothes. Some of the common types of wearable technology include smartwatches, smart glasses, and smart jewelry like rings and wristbands. These devices track, analyze, and transmit personal data.
One of the most prominent applications of wearables has been found in healthcare. They can be used to monitor body temperature, blood pressure, heart rate, and other vital signs. The application of these devices further extends to physiological diseases like hypertension and muscle disorders as well as neurocognitive disorders such as Alzheimer’s disease and Parkinson’s disease. Wearables are also being utilized as a drug delivery system, helping personalize healthcare.
Different types of wearable devices are currently being used in the healthcare field. This includes skin-based wearable devices such as e-skin, wearable vests, smart rings, earphones, and biofluidic-based devices that make use of saliva, tears, and urine.
In addition to healthcare, wearables are used to communicate with others, make payments, and track activity levels, as well as lifestyle, gaming, sports, fitness, security, and defense sectors.
Over the years, wearable technology has advanced in various ways. For starters, researchers and companies are always looking for better materials to build these devices. Flexible, stretchable materials and soft, ultra-thin designs allow these devices to be worn comfortably and maintain their functionality.
For instance, gallium-based liquid metals, which have high conductivity and biocompatibility, are leading the way for bioelectronics that fit better with the body.
As for designs, tech has evolved significantly from conventional ways, with a greater focus now on making them seamlessly integrated with the human body. E-tattoos are a great example of this; they are extremely thin, skin-soft electronics that conform to the skin and can noninvasively digitize physiological and psychological information.
Miniaturization of these devices, along with printed electronics and intelligent fabrics, has led to sensors that can monitor a variety of physical parameters while electrodes are being embedded in textiles to measure activity. For example, Wearable sweat sensors continuously and noninvasively monitor health indicators through sweat to empower precision medicine.
Source: MDPI
A lot of advancement is also being made in wearable smart chemical sensors, which are finding increasing application in healthcare, environmental monitoring, and safety assessment.
Various innovative approaches have been taken to sensor design and fabrication, with one such system designed to detect NO2 by incorporating a polyvinyl alcohol/borax/agarose/NaNO3 electrolyte and multi-walled carbon nanotube electrodes on gold nanosheets. The system shows enhanced performance and self-repairing capabilities, making it perfect for wearable applications.
Overcoming Limitations of Wearable Tech
With all these innovations helping wearable devices become better and more effective, they have been seeing transforming different industries, especially healthcare. However, they suffer from limitations like stability and privacy.
For instance, the data received from the sensors in these wearables may experience distortion and noise due to constant body motion.
Batteries used in wearables present another significant challenge. The limitations of power sources have prompted researchers to explore various solutions, such as piezoelectric nanogenerators (PENG), which function as self-powered sensors, and triboelectric nanogenerators (TENG), which serve as miniaturized energy harvesters.
Thermoelectric generators, in particular, have been gaining a lot of traction in the wearable tech space. Back in 2017, researchers from Zhejiang University and Xidian University released a paper on the design of a wearable thermoelectric generator for harvesting the energy of the human body.
Much like the latest research, this one also utilized Bi2Te3-based thermoelectric material to create a device that could generate a voltage of 48 mV for a temperature difference of 12 K. When mounted onto the human wrist skin, the thermoelectric generator’s output power was 130.6 nW at an ambient temperature of 25 °C, demonstrating its potential for human body heat energy harvesting and development of wearable self-powered mobile devices.
Yet another study made advancements in the design of thermoelectric generators (TEGs) for body heat harvesting applications. The thing is, there’s a 10-15°C temperature difference between the body temperature and the ambient temperature, but only a tiny portion passes through a wearable TEG because of the thermal resistance of the skin.
To overcome the challenges for wearable TEGs, a comprehensive quasi-3D analytical model was developed, and then a microwave processing technique was used to synthesize high-performance thermoelectric nanocomposites, which led to a strong reduction of the thermal conductivity and resulted in TEGs exhibiting 4-7x higher power density than commercial TEGs on the human body.
Just this year alone, several research studies have been released focusing on thermoelectric devices for wearables.
A few months ago, researchers from the University of Washington also developed a highly flexible and soft prototype that can harvest energy from body heat and turn it into electricity, which can then power small electronics. For its flexible thermoelectric devices (TEDs), the UW team used 3D soft architectures, rigid semiconductors, multifunctional composites, and self-healing liquid metal conductors.
In addition to energy harvesting, the focus of all these studies has been on the development of lightweight and flexible thermoelectric materials, designing adaptable surfaces to fit diverse body parts, enhancing the functionality of wearables, and achieving cost-efficiency and scalability.
The Rapidly-Growing Wearable Market
The advancement in wearable technology and the resulting boost in functionality have increased the adoption of these devices. The growing interest in wearable devices has its market projected to grow past $150 billion before this decade is over.
The market for wearables like smartwatches and fitness trackers, in particular, has been rising for some time. They actually boomed during the pandemic as personal health became everyone’s focus. These devices are also adding an increasing number of metrics, and as they move closer to that of a medical device, more and more consumers are adopting them.
Besides fitness and healthcare, tech giants are taking a special interest in virtual, augmented, and mixed reality (VR, AR & MR) wearables. Smart clothing and e-textiles have also been garnering attention but continue to face challenges in terms of manufacturing scalability and product economics.
Interestingly, the wearable payments services market is expected to grow at a strong pace, with a CAGR of 13.6% to $120 billion. This growth is propelled by the adoption of near-field communication (NFC) in smartphones, fitness trackers, and other wearables,
Wearable technology product types further involve electronic skin patches, chest straps, smart contact lenses, and wearable cameras, which are also of interest.
According to a recent report, the shipments of wearable devices globally are expected to grow more than 6% year over year (YoY) this year to almost 538 million units. This growth is driven by the improving economy and the growing adoption of wearables in emerging regions.
This growth, however, will be uneven across the sectors, with wearables, representing over 60% of the wearables market, expected to see a boost as prices stabilize. Smartwatches, meanwhile, are expected to see a 3% decline, the first-ever YoY drop, though they are projected to rebound to 4.8% growth next year. This is due to rising prices and minimal design changes.
Emerging Wearable Devices
When it comes to emerging wearable devices, the fitness and healthcare sectors are leading the charge.
In healthcare, wearable electrocardiogram (ECG) devices, which come in smartwatches and patches, are transforming remote cardiac care. These devices pair with apps that store ECG data, which physicians can review remotely and then provide proactive health management, leading to healthier lifestyles.
Today’s wearables also enable continuous collection of vital signs with the help of advanced sensors that provide real-time data about their wearers. For instance, Continuous glucose monitoring (CGM) offers real-time insights into blood sugar levels, allowing patients to monitor their health right from the comfort of their homes.
An increasing focus among companies is also seen on heart rate monitors. Smartwatches like Casio G-Shock Rangeman come equipped with a heart rate monitor to accurately detect body movement as well as changes in the natural environment with the help of GPS and sensors. Then there are Garmin‘s (GRMN -0.2%) heart rate monitors, which come with a comfortable design allowing women to clip them directly onto their sports bras.
As we can see, ease of access is certainly the point of focus for tech companies developing wearables. This is also true for Oura smart rings, which can be worn on a finger. The band is equipped with a 3D accelerometer to determine movement, an NTC sensor to observe your body temperature, and a PPG sensor to track your heart rate.
Then there’s Evie Smart Ring, which has taken a women-first approach to its design by enabling tracking sleep, heart health, and menstrual cycles. Wearable biosensors, meanwhile, offer promising avenues for stress management by detecting subtle changes in biomarkers like cortisol levels.
Companies are also building headphones that guide wearers during workouts, while special gloves like GyroGlove are created for Parkinson’s patients to reduce tremors and improve quality of life.
In the world of entertainment, wearables like Xreal Air allow users to watch content and play games, while Meta‘s (META +0.72%) smart glasses enable content creation and sharing. Then there are wearables like the Ai Pin, which runs on an eight-core, 2.1 GHz Qualcomm processor and can take photos, send text messages, and answer calls.
Click here to learn about thermal earring.
Companies Dominating the Wearable Sector
Now, when it comes to companies, Apple (AAPL +1.1%) has been leading the space thanks to its robust portfolio of smart products like the Apple Watch. Key health metrics covered by the watch include heart rate, respiratory rate, wrist temperature, blood oxygen, and sleep duration.
The world’s largest company in the world by market cap of $3.75 trillion has its shares currently trading at $248, up 28.88% this year. Apple has an EPS (TTM) of 6.07 and a P/E (TTM) of 40.88 while having a 0.40% dividend yield. For the quarter ended September 28, 2024, in which the company launched its iPhone 16 lineup, AirPods 4, and Apple Watch Series 10 with features for hearing health and sleep apnea detection, the tech giant posted a revenue of $94.9 billion.
Meanwhile, Google is capturing the wearable market through Fitbit, which it acquired in 2021. The Chinese company Huawei also launched its TruSense system this year to power upcoming wearables. Other notable names in the space include Samsung Group (SSUN.F -0.26%), Sony Corporation (SONY -0.9%), Microsoft (MSFT +0.91%), and Garmin.
Conclusion
Wearable technology is a rapidly growing market that is seeing a lot of interest and development. Moreover, breakthroughs in thermoelectric technology, as achieved by the QUT team, are paving the way towards a more advanced future where these devices are not dependable on batteries anymore, in turn leading to lightweight and more efficient wearables.
But while all these advancements in material and design are driving the global wearables market, there are still challenges with regard to cost, scalability, and durability. It is only through further innovation, continued collaboration, and increased investment that all these breakthroughs can be put to use in practical applications and integrated into our daily lives!
Click here for a list of top wearable health tracking companies to invest in.
