Zhenan Bao rummages through a plastic box on her desk, eagerly pulling out samples of materials developed in her lab. She finds a thin, nearly weightless patch made of carbon nanotubes that attaches to the wrist like a sticking plaster and monitors the wearer's heart rate. Then she picks up an artificial skin that uses tiny carbon-nanotube sensors to detect touch; and a version of it that even features hair-like structures to more closely mimic real skin.
Bao, a chemical engineer at Stanford University in California and a founder of the field of thin, flexible organic electronics, shines a laser pointer through a sample of the nanotube material used in many of these devices. She laughs as the beam is diffracted into a spray of green dots on the wall, just as it would be when passing through a crystalline material. "That's how we know it has regular structure," she says.
The inside story on wearable electronics
Innovations in her field are often inspired by nature, she says: "If we can understand how to design materials with the same degree of complexity, we will be able to address real-world problems." A prime example is the creation of medical devices that can be worn or implanted to monitor blood sugar, send sensory signals and more.
Progress towards that goal has taken off this year, with Bao's lab among the leaders. In October, her team showed that its artificial skin could mimic the sense of touch (B. C.-L. Tee et al. Science 350, 313–316; 2015). The researchers took inspiration from human skin, in which specialized nerves fire more rapidly as pressure increases, producing a code that the brain interprets as touch. Previous artificial touch sensors required power-hungry external devices to generate that code. But in Bao’s sensors, pressure alters the oscillating frequency of microscopic circuits made from carbon nanotubes to generate the right kind of signals automatically.
Although Bao calls the final design "simple", it was a major accomplishment, says Polina Anikeeva, a neural-interfaces and materials scientist at the Massachusetts Institute of Technology in Cambridge. She notes that Bao has been working on perfecting these materials for years, and that her lab — which comprises around 40 chemists, chemical engineers and materials scientists — is highly interdisciplinary. "It's not just one idea," she says, "many ideas came together and made this possible."
"We have many years of work to do," says Bao, who hopes that the treasures she keeps in the plastic box will one day help to revolutionize health care. "But generally, the path is laid out."
Congratulations, Professor Bao!