Stretchy, Soft, and Sticky: Advancing the Next Generation of Wearable and Implantable Sensors
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Stretchy, Soft, and Sticky: Advancing the Next Generation of Wearable and Implantable Sensors
Stretchy, Soft, and Sticky: Advancing the Next Generation of Wearable and Implantable Sensors
June 10, 2026
Wearable and implantable biosensors have the potential to revolutionize health care by diagnosing, monitoring, and even treating a wide range of health conditions. Recent innovations in the lab of Wei Gao, professor of medical engineering at Caltech and a Heritage Medical Research Institute Investigator, are pushing the field forward through the creation of soft, stretchable, tissue-integrated bioelectronics for continuous sensing and adaptive therapy. Two new studies highlight complementary gains in materials and technology while addressing different challenges and applications.<br>Sensors That Stretch<br>To allow for medical sensing that can move flexibly with the body and even internal organs such as a beating heart, scientists in the Gao lab have developed a bioelectronic material that maintains conductivity and a strong connection with the skin or tissues as they deform. The super-stretchy biocompatible interface meets a key need for the next generation of wearable and implantable sensors.<br>The new material, aptly called a stretchable interface for resilient electrochemical sensing (SIRES), can stretch as much as 300 percent without losing its ability to transmit high-quality electrical signals. Gao and his colleagues describe SIRES in a paper that appeared in the May 28 issue of the journal Science.<br>When researchers attach a chemical sensor to an internal organ, they are trying to measure biomolecules that signal health status. But because of the materials used to create these sensors, often when the organ moves, the sensor either fails or becomes unreliable in its performance. To address this, Gao's team—led by Yadong Xu, a former postdoctoral scholar from Gao's lab, and Caltech graduate students Xiaotian Ma (MS '24) and Kexin Fan—developed a three-part material that makes use of polyurethane, an elastomer (a rubber-like solid) that is also biocompatible.<br>First, rather than using standard conducting wire within the device, the researchers turned to liquid metal to act as the conductor. Liquid metal can stretch yet maintain the same electrical resistance. Therefore, by mixing liquid metal with polyurethane, the scientists created a strain-resilient conductor.<br>Second, they created a stable flexible electrode for sensing. Normally, the electrodes in biosensors are made from a metal such as gold or from carbon nanotubes, but these can crack with even a tiny bit of stretching. The nanotubes are excellent at detecting electrical changes when a target molecule binds to their surface. Gao's team embedded carbon nanotubes in polyurethane, giving the nanotubes the ability to stretch while remaining interconnected. When the collection of nanotubes elongates, some of the connections between individual nanotubes break, causing electrical conductivity to decrease. But because the overall surface area of the electrode also increases with stretching, more molecules can be exchanged at the sensor, and this counteracts the decrease.<br>"If you tune the carbon nanotube level properly, the two effects balance out, and you get a stable response," says Gao, who is also a Ronald and JoAnne Willens Scholar. "So even in the case of an organ that deforms a lot, such as a beating heart, your sensor performance will not change."<br>The third component of SIRES is a stretchable functional coating of polyurethane that allows the researchers to embed any enzymes needed for chemical sensing inside.<br>"The conductor, the electrode, and the functional film are all made of polyurethane embedded with different things. That means the whole thing is very stretchable and also biocompatible," Gao says.<br>The team has tested SIRES with the group's sweat sensors, showing that even with vigorous exercise, the sensors maintain stable performance. They have also tested the material successfully in implantable sensors in animal models on organs such as the bladder, heart, stomach, and intestines—all of which deform significantly during normal functioning.<br>A Platform That Sticks<br>Another challenge in making reliable implantable sensors is they must stay attached to slick surfaces, hopefully for long periods of time. In a Nature Materials paper published June 10, Gao and members of his lab reported on a new device that not only sticks to organs and other internal structures but can also provide therapeutic interventions as needed.<br>"What's exciting about this work is that we developed a soft stretchable implantable platform that can firmly adhere to wet tissues while remaining stable even as the body moves," says Jiahong Li (PhD '26), a postdoctoral scholar in Gao's lab and first author of the paper. "The device can simultaneously...