The skin is the largest organ in our body, and the most complex. Look under a microscope and you’ll see thousands of nerves that insulate the brain from the outside world and allow us to feel touch, pressure, and pain. But when Zhenan Bao looked, he saw something else.
For Bao, a chemical engineer who focuses on developing polymers, the skin is not only a sensory organ, but also an object. One that, in his words, is flexible, and expansive, self-healing, and malleable. Bao works in the emerging field of electronic skin and has made it his mission to reengineer many of the functions of human skin for use in prosthetics and robotics. For people who wear artificial limbs, touch can improve their lives immeasurably—it helps them distinguish between soft and hard and detect sharp or hot objects before they cause damage.
When Bao joined Stanford University in 2004, a few researchers were working on flexible sensors that could wrap around an artificial hand to mimic touch, and Bao’s previous experience with displays could be useful. By 2010, Bao and his colleagues had developed a device that could detect the touch of a butterfly.
“The electronics we have here are very strong, durable, and versatile,” Bao says. “But if we can make them all like a skin, then it could change the way people interact and interact with electronics.” Our skin, which forms a natural barrier against the environment, can also act as a connection between people and materials.
In addition to robotics and prostheses, Bao sees potential applications for electronic skin, or e-skin, in the field of clothing. Imagine a device that is worn on the body like a second skin and uses sensors to accurately measure blood pressure, temperature, or glucose and oxygen levels in real time. “There’s a lot of interest in wearables that go beyond just measuring how many steps we walk each day or heart rate,” says Bao.
One product from Bao’s research lab at Stanford could be developed and clinically tested in the next few years. Silicon Valley startup PyrAmes, which Bao founded, is developing a soft band that wraps around the arm or foot and can be used to monitor the blood pressure of premature babies in intensive care units. They are designed to record blood pressure continuously in the same way that a vein line does, without the need for needles that carry the risk of infection, tissue, and nerve damage. The band is connected wirelessly to a tablet to monitor blood pressure changes in real time.
For such things, electronics must be flexible and flexible from the start. Bao’s team of researchers has taken the approach of developing natural polymers with this in mind. A polymer is a large molecule made up of many repeating monomers linked together as long paper chains. By changing the shape of these monomers, researchers can make the material expand and make it compatible with or even inside the human body.