Stretchable Wearable Electronics Make Major Strides in 2024

In 2024, the landscape of wearable technology experienced a monumental shift with groundbreaking advancements that promise to make soft, body-conformable electronics and power sources a reality. Researchers worldwide are pushing the boundaries with improved flexible sensors and displays, while engineers have unveiled exciting new technologies. One notable development is a self-healing, stretchable lithium-ion battery from China, capable of powering next-generation wearables. LG Display also introduced a stretchable screen that can extend from 12 to 18 inches, further cementing their role in this innovative field.

Advancements in Stretchable Sensors

Recent progress includes skin-like devices equipped with high-density stretchable sensor arrays. A Stanford-led team recently created an array featuring more than 2,500 transistors per square centimeter. These sensors maintain functionality even when bent, twisted, or compressed, setting a new standard for sensitivity and durability. Such technology could evolve into health-monitoring patches that adhere seamlessly to the skin, collecting vital health data such as cardiovascular information, muscle signals, and glucose levels.

Stanford is also exploring stretchable transistors and integrated circuits | Image courtesy of Donglai Zhong, Jiancheng Lai, and Yuya Nishio of the Bao Group

Flexible Displays

Industrial laboratories are also making strides in flexible displays capable of stretching up to 50%. This technology could be embedded into clothing or incorporated into automotive dashboards. The displays, made using techniques like soft transfer printing and 3D structure fabrication, ensure that LEDs remain fully functional under significant deformation. LG has led with prototypes that can extend and contract, envisioning applications like expandable visual screens embedded in first-responder uniforms for real-time data display.

A review in npj Flexible Electronics by Ruilai Wei and colleagues outlines key fabrication methods accelerating the development of body-conforming electronics. Techniques such as roll-to-roll processing, kirigami-inspired manufacturing, and shape-memory polymer transfer are enhancing scalability and durability. The ultimate goal is to create reliable sensors and displays that can withstand everyday movements, improving the accuracy of data collected from the human body.

Hydrogel Semiconductors

Scientists at the University of Chicago’s Pritzker School of Molecular Engineering have developed a groundbreaking hydrogel semiconductor that combines the flexibility of a hydrogel with semiconductive properties. This bluish, jelly-like material can reduce inflammation and enhance biosensing capabilities, making it ideal for implants like pacemakers and drug-delivery systems. The hydrogel semiconductor maintains the flexibility of a hydrogel while enabling signal transmission between the body and electronic devices, offering unprecedented comfort and compatibility with living tissue.

University of Chicago/John Zich

Injection-Molded Soft Connections

Michael Bartlett and his team at Virginia Tech have advanced the creation of soft electronic connections without drilling holes. Their method, published in Nature Electronics, uses ultraviolet exposure to form stair-like formations of liquid metal microdroplets. These vertical channels enable robust electrical conduction through flexible layers, even under significant bending and twisting. The approach can fabricate multiple vias in under a minute, offering potential for broader applications in soft robotics and wearable health monitors.

By embedding liquid metal droplets in photoresin and using natural stratification, the Virginia Tech team demonstrated the ability to create interconnects from in-plane interconnects to 3D through-plane connections. These printed vias are sealed in a paper-like layer, maintaining mechanical reliability while preserving softness. This advancement brings us closer to the development of advanced soft robotics and wearable devices that can maintain high functionality even when stretched, bent, or twisted.

The Future of Wearable Technology

These breakthroughs represent a significant leap forward in the field of wearable technology, offering a glimpse into a future where health-monitoring devices and smart clothing are seamlessly integrated into our everyday lives. As researchers continue to refine these technologies, we can anticipate more sophisticated and functional wearable gadgets that go beyond simple fitness tracking.

The combination of stretchable sensors, flexible displays, hydrogel semiconductors, and soft electronic connections paves the way for devices that are both durable and comfortable. These innovations have the potential to revolutionize healthcare, enhancing our ability to monitor health in real-time and respond to changes more effectively. As this technology advances, the possibilities for smart fabrics, adaptive medical devices, and innovative electronic clothing continue to expand.

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