Scientists have discovered a new way to make a soft, stretchy plastic that can carry electricity efficiently—an advance that could help improve devices implanted in the human body, such as pacemakers, glucose monitors, and nerve sensors.
The research, led by chemical engineering professor Enrique Gomez at Penn State, focuses on a material called PEDOT:PSS.
This gel-like plastic is already used in technologies like soft robots and touchscreens because it can conduct electricity while remaining flexible.
What makes it especially interesting for medicine is that it can interact with the body’s own electrical signals.
The human body and electronic devices both use electricity, but in very different ways. Computers move electricity using electrons through metal wires and semiconductors.
In contrast, nerves in the body send signals using ions—charged particles dissolved in fluids like salt water.
PEDOT:PSS is unusual because it can handle both types of electrical flow, making it a promising bridge between biology and electronics.
To better understand how this plastic works, the research team used one of the most powerful imaging tools available: cryogenic electron microscopy, or cryo-EM.
Instead of using light like a regular microscope, cryo-EM uses beams of electrons and extremely low temperatures to reveal structures at the atomic scale.
The scientists froze tiny droplets of the material at about minus 180 degrees Celsius, allowing them to see details that are normally impossible to observe.
They discovered that adding small amounts of salt and water caused the plastic to grow countless microscopic fibers that look like tiny whiskers.
These fibers form pathways that allow electricity and ions to move through the material more easily. Samples with salt additives had many more of these whiskers and conducted electricity better than samples without them.
Water also played a crucial role. When the plastic absorbed water, it became softer and stretchier—important qualities for materials that need to move with the body without breaking. Lithium salts were especially effective because they helped the material absorb even more water. Without water, however, the plastic became brittle, showing that moisture is essential for keeping it flexible.
Surprisingly, the researchers found that the material’s electrical performance stayed stable even when it was swollen with water. The tiny fibers created by the salt remained in place, allowing the plastic to stay conductive while becoming soft and elastic. This rare combination of stretchiness and steady conductivity is exactly what engineers need for next-generation bioelectronic devices that must bend, twist, and stretch inside the body.
Although the discovery answers some questions, many remain. Scientists still do not fully understand how the salts trigger the growth of the whisker-like fibers or how to fine-tune the process.
Future studies will explore how to optimize the material for specific uses, from long-lasting heart implants to skin-mounted sensors and tests that measure nerve and muscle activity.
If researchers can master this technology, the result could be a new class of medical devices that are more comfortable, longer-lasting, and better able to communicate with the body’s natural electrical systems.
