Stretchable Skin-like Electronics that Senses a Bug’s Footsteps
Setting the stage for an imminent revolution in the field of medical research, Stanford scientists have now developed a new polymer circuitry with integrated touch sensors may one day lead to coverings for prosthetic devices that have skin-like sensitivity. Further, this very tech could, in the near-future, become the foundation for the evolution of new genre of flexible electronics that are in stark contrast with rigid smartphones that many of us carry, gingerly, in our back pockets.
Skin-like electronics that can adhere seamlessly to human skin or within the body are highly desirable for applications such as health monitoring , medical treatment , medical implants and biological studies , and for technologies that include human–machine interfaces, soft robotics and augmented reality.
Rendering such electronics soft and stretchable—like human skin—would make them more comfortable to wear, and, through increased contact area, would greatly enhance the fidelity of signals acquired from the skin.
“It detects pressures well below the pressure exerted by a 20 milligram bluebottle fly carcass we experimented with, and does so with unprecedented speed,” said Zhenan Bao, an associate professor of chemical engineering who led the research.
“Research into synthetic skin and flexible electronics has come a long way, but until now no one had demonstrated a process to reliably manufacture stretchable circuits,
” Stanford chemical engineer Zhenan Bao said.Bao’s hope is that manufacturers might one day be able to make sheets of polymer-based electronics embedded with a broad variety of sensors, and eventually connect these flexible, multipurpose circuits with a person’s nervous system. Such a product would be similar to human skin, a more complex biochemical sensory network. Before it leads to artificial skin, the process will enable the creation of foldable, stretchable touchscreens, electronic clothing, or skin-like patches for medical applications.
The new artificial skin is formed by layers of hi-tech polymers. Some layers enhance the skin’s elasticity. Other layers feature the electronic meshing that allows the circuitry to be embedded in the skin. Still more layers help insulate the electronic components and provide waterproofing. The team has successfully fashioned its material in squares about two inches on a side containing more than 6,000 individual signal-processing devices that act like synthetic nerve endings. All this is encapsulated in a waterproof protective layer.
“We’ve engineered all of these layers and their active elements to work together flawlessly,” said post-doctoral researcher Sihong Wang.
The prototype can be stretched to double its original dimensions – and back again – all the while maintaining its ability to conduct electricity without cracks, delamination or wrinkles. To test durability, the team stretched a sample more than one thousand times without significant damage or loss of sensitivity. The real test came when the researchers adhered their sample to a human hand.
“It works great, even on irregularly shaped surfaces,” said postdoctoral scholar Jie Xu, and the paper’s other co-lead author.
As Bao’s team continues their research, they may find applications not yet considered as well as other ways to demonstrate the sensitivity of their sensors. They have already expanded their stable of insects beyond the bluebottle fly to include some beautiful, delicate looking – albeit slightly heavier – butterflies.
Scientists hope the new layering approach will pave the way for the production of polymers with all kinds of embedded electronic circuits and sensors. While researchers say they need to improve upon the speed of the current prototype’s electronic system, scientists are confident the technology could soon replace more rigid electronic components and circuitry.
“I believe we’re on the verge of a whole new world of electronics,” Bao said.
