A research team from the Northwestern University’s McCormick School of Engineering has created a design that enables development of highly stretchable electronics for medical applications. The design allows a device to stretch and bend over 200% of its original size, which is four times higher than the current technology. This is achieved by a combination of liquid metal and porous polymer.
Yonggang Huang, Joseph Cummings Professor of Civil and Environmental Engineering and Mechanical Engineering, noted that by using the existing technology, electronics are stretched to only a small amount. However, several potential applications need a device that bends and stretches like a rubber band. This level of stretchability can enable integration of medical monitoring devices into the human body, added Huang.
Huang conducted the research along with the scientists from the University of Illinois at Urbana-Champaign, Dalian University of Technology in China; and the Korea Advanced Institute of Science and Technology in South Korea for the past five years. They have developed electronic devices with approximately 50% stretchability, which is not sufficient for several applications. A conductivity loss in stretchable electronics is one of the challenges faced by the team. Electronic circuits produced from solid metals can resist a small amount of stretch, whereas their electrical conductivity decreases by 100 times when they are stretched.
To overcome these challenges, the researchers first developed a highly porous 3-D structure using a polymer called poly(dimethylsiloxane) (PDMS). The material has an ability to stretch to three times its original size. Later, the team placed a liquid metal, EGaIn, within the pores, thus allowing a consistent flow of electricity even when the polymer material is extremely stretched. The process resulted in an extremely stretchable and highly conductive material.