Researchers at MIT have designed a stretchable hydrogel electronic material that acts as a smart wound dressing. Details are described in Advanced Materials.
According to a press release, the material can incorporate temperature sensors, LED lights and drug-delivering reservoirs and channels. It also can respond to changes in skin temperature and can be designed to light up if medicine is running low.
The material is made from a hydrogel matrix designed by Xuanhe Zhao, PhD, the Robert N. Noyce Career Development Associate Professor in the Department of Mechanical Engineering. The rubbery material is mostly composed of water and can bond strongly to surfaces like gold, titanium, aluminum, silicon, glass and ceramic.
“Electronics are usually hard and dry, but the human body is soft and wet. Those two systems have drastically different properties,” Zhao said in the press release. “If you want to put electronics in close contact with the human body for applications, such as health care monitoring and drug delivery, it is highly desirable to make the electronic devices soft and stretchable to fit the environment of the human body. That is the motivation for stretchable hydrogel electronics.”
Synthetic hydrogels tend to be brittle without the inability to stretch or adhere to other surfaces, according to the press release.
“They are often used as degradable biomaterials at the current stage,” Zhao said. “If you want to make an electronic device out of hydrogels, you need to think of long-term stability of the hydrogels and interfaces.”
Zhao and colleagues mixed water with a small amount of selected biopolymers to create soft, stretchy materials within the stiffness range of human soft tissues and devised a method to bond the material to nonporous surfaces.
In experiments, the researchers encapsulated a titanium wire in the hydrogel and found the wire maintained constant electrical conductivity when stretched multiple times. They also embedded an array of LED lights in the sheet of hydrogel and found the array continued to work, even when stretched across deformable areas.
Zhao and colleagues also embedded various electronic components within the material to create a “smart wound dressing,” including regularly spaced temperature sensors and tiny drug reservoirs. They also inserted patterned tubes and drilled tiny holes through the material to create pathways for drugs to flow through the hydrogel. After placing the dressing over various regions of the body, they found even when highly stretched the material continued to follow sensor readings to monitor skin temperature and release drugs.
Hyunwoo Yuk, an MIT graduate student and co-author of the paper, said the material may be used as a stretchable, on-demand treatment for burns or other skin conditions.
“It is a very versatile mix,” Yuk said in the press release. “The unique capability here is, when a sensor senses something different, like an abnormal increase in temperature, the device can on-demand release drugs to that specific location and select a specific drug from one of the reservoirs, which can diffuse the hydrogel matrix for a sustained release over time.”
Zhao said the material also could eventually be used to deliver electronics inside the body, such as glucose sensors and neural probes.
Zhao X, et al. Adv Mater. 2015;doi:10.1002/adma.201504152.
Disclosures: The researchers report the research was funded in part by the Office of Naval Research, the MIT Institute for Soldier Nanotechnologies and the National Science Foundation