Researchers at Carnegie Mellon University have developed a silver-hydrogel composite that can conduct electricity, which looks promising for use in a variety of bioelectronics applications. These include skin mounted electrodes for neuromuscular stimulation that may be helpful in treating muscular disorders or other motor issues. Soft materials are expanding the possibilities for biomedical devices that can safely and delicately interact with human tissues. Often, such materials are made using hydrogels, but most hydrogels cannot conduct electricity, meaning that they lack a property that would be very useful in biomedical sensors and robotics. This may be about to change. These researchers have developed a new silver-hydrogel composite that is electrically conductive, and can deliver direct current while maintaining its stretchable and flexible nature. In a recent study, the researchers have demonstrated its potential as a component in bioelectronic devices and soft robotics. “With its high electrical conductivity and high compliance or ‘squishiness,’ this new composite can have many applications in bioelectronics and beyond,” said Carmel Majidi, a researcher involved in the project, in a Carnegie Mellon press release. “Examples include a sticker for the brain that has sensors for signal processing, a wearable energy generation device to power electronics, and stretchable displays.” The researchers created the material by suspending tiny silver flakes in a polyacrylamide-alginate hydrogel, and then partially dehydrated the gels. The flakes formed an interpenetrating network throughout the gel that could conduct electricity, but which was not disrupted by the gel moving and flexing. Cleverly, by hydrating or dehydrating the gel, the researchers can change the connections between the silver flakes, meaning that the electrical connections can be turned on or off. So far, the Carnegie Mellon team tested the potential and versatility of the hydrogel by using stencil lithography to print electrodes that can be attached to the skin to stimulate the muscles beneath. The devices may have potential as a means to create therapeutic neuromuscular stimulation in conditions such as Parkinson’s disease. They have also demonstrated its potential in creating soft robots by creating a soft stingray robot that can swim, and which wouldn’t look out of place in the Alien movie franchise. Source
