Breaking the "discomfort" of wearable electronic devices? A new material opens a new era of smart wearables!

□ Li Chuanfu

With the rapid development of technology, wearable electronic devices have gradually become an indispensable part of most people's lives. From smart watches to monitor health data, to smart clothes to provide a comfortable experience, these innovative products are changing the way we interact with technology. However, for a long time, a key technical problem has limited the development of wearable electronic devices, that is, the rigidity of traditional electrode materials.

The emergence of soft elastic electrode materials has brought a turnaround to this dilemma. Recently, scientists from the University of California, San Diego, published a new scientific research result in the journal Science Robotics, a wearable electronic device developed from a polymer electrode material that is both conductive and stretchable, which will not increase the wearer's discomfort.

Traditional electrode materials, such as metals and rigid inorganic compounds, perform well in terms of conductivity, but their mechanical properties cannot meet the needs of wearable devices. Human skin is soft and elastic, and rigid electrode materials cannot fit closely to the skin, resulting in inaccurate and unstable signal acquisition. This is a severe test for wearable devices that rely on accurate biosignal monitoring, such as heart rate monitors and blood glucose meters.

In order to solve the limitations of traditional electrode materials, scientists are committed to developing various soft and elastic electrode materials. At present, the main soft and elastic electrode materials include conductive polymers and carbon nanomaterials such as graphene and carbon nanotubes.

Conductive polymers have good flexibility and processability, and their conductivity can be regulated by chemical doping or structural design. For example, conductive polymers such as polyaniline and polythiophene can still maintain good conductivity in stretched and bent states, and can be prepared into films or fibers by solution processing, which are suitable for large-area wearable electronic devices.

As representatives of carbon nanomaterials, graphene and carbon nanotubes have excellent electrical conductivity, mechanical strength and flexibility. Graphene is a two-dimensional material composed of a single layer of carbon atoms, with extremely high carrier mobility and excellent flexibility; carbon nanotubes are one-dimensional nanomaterials with a large aspect ratio and can maintain good electrical conductivity when bent and stretched. Researchers can prepare high-performance soft elastic electrodes by combining these carbon nanomaterials with polymers.

There are many methods for preparing soft elastic electrode materials. Chemical synthesis is a common method for preparing conductive polymers. By controlling the reaction conditions and the ratio of reactants, soft elastic electrode materials with specific structures and properties can be precisely synthesized. For example, when synthesizing conductive polymers, the conductivity and flexibility can be optimized by adjusting the type and concentration of dopants. Solution processing is a simple, low-cost method that is easy to mass produce. For example, researchers dissolve conductive polymers in appropriate solvents and prepare them into thin films or patterns by spin coating, inkjet printing, or screen printing. Similarly, carbon nanotubes and graphene can also be prepared into soft elastic electrodes by solution processing.

The emergence of soft elastic electrode materials has brought a wide range of application prospects for wearable electronic devices. In the field of health monitoring, soft elastic electrodes can be integrated into smart bracelets, smart patches and smart clothing to monitor physiological parameters such as heart rate, blood pressure, blood sugar, and body temperature in real time. These electrodes can fit the skin tightly, accurately collect biological signals, and provide reliable data support for medical diagnosis and health management. In terms of sports tracking, soft elastic electrodes in wearable devices can monitor athletes' movements, postures, and muscle activities, helping them optimize their training programs, improve their performance, and reduce the risk of injury. In the field of human-computer interaction, soft elastic electrode materials can be applied to devices such as smart gloves and smart watchbands to achieve more natural and intuitive operation methods. For example, by detecting the bending and touch movements of fingers, soft elastic electrode materials can realize the control of electronic devices. In addition, they can also be used in energy harvesting and storage devices, such as flexible solar cells and supercapacitors, to provide a continuous energy supply for wearable devices.

In the future, soft elastic electrode materials will continue to innovate and improve, making wearable electronic devices thinner, more comfortable, smarter and more multifunctional. They are not just auxiliary tools in our lives, but are more likely to become a part of our bodies, bringing unprecedented convenience and experience to people's health, work and entertainment.

(The author is an engineer at the Green Energy Industrial Research Center of Huazhong University of Science and Technology and a member of the Royal Society of Chemistry)