Transparent Artificial Muscle Plays Music
Eliza Grinnell, Harvard SEAS Communications
Jeong-Yun Sun (left) and Christoph Keplinger (right) demonstrate their transparent ionic speaker, which uses ions, rather than electrons, to vibrate a rubber membrane.
Sept. 27, 2011 --
In the popular "Deus Ex" video game series, nanotechnology can turn an average government agent into a bionic superman. In fact, nanotech augmentations in the human body aren't just fun and games. Real-life applications will most likely become reality a lot sooner than you think. In 2007, the world's first online inventory of nanotech products, Project on Emerging Nanotechnologies, found that nearly 500 products, including food, clothing and cosmetics, employed nanotechnology. In this slide show, explore how nanotech can make you stronger, tap into your brain and more.
WATCH: NANOTECH REWARDS
If you're too busy to make it to the gym, nanotechnology could be a way to get fit without having to spend hours toiling away on machines. In fact, technology can take you a lot further than any free-weight or cardio regimen. In 2006, researchers at the University of Texas at Dallas reported in the journal Science that they had created alcohol- and hydrogen-fueled artificial muscles 100 times stronger and capable of 100 times more work than natural muscles. Functioning as both muscles and fuel cells, the technology has a range of applications from artificial limbs to autonomous robots.
SCIENCE CHANNEL: Take the Nanotechnology Quiz
If nanotechnology can make you stronger, could it also make you smarter? Scientists aren't quite there yet, but nanotechnology applied to brain implants could treat a range of conditions from deafness to blindness to Parkinson's disease and more, according to biomedical engineers from the University of Michigan. Nanotechnology could also be used to tap into the mind, and read and write information directly into the brain. In an unusual twist, the research was undertaken by telecommunications engineers at Nippon Telegraph and Telephone.
University of Washington
Contact lenses with visual displays may seem like the kind of technology you only see in a movie. But researchers at the University of Washington have started laying the groundwork by building a contact lens with internal circuitry. Using wires made of metal only a few nanometers thick, the technology is placed in a contact lens rather than an implant, making use of the bionic eye much easier. In this photo, the contact lens has been affixed to a rabbit. The researchers believe they would quickly be able to introduce a visual display, but it wouldn't be more than a few pixels in the near future.
Tired of having to find an electrical outlet or a USB cable every time you need to charge your cell phone? With nanotechnology, you can become a walking battery. Using nanowires to recover wasted heat energy from the body, which is then converted into electrical power, researchers with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and the University of California at Berkeley have developed an entirely means of charging personal electronics. The same technology could be used to convert heat from other sources into electrical energy. As reported in the journal Nature, approximately 15 trillion watts of heat energy produced by engine and steam- and gas-powered turbines is lost to the environment.
Recovering from injuries to skin and muscle tissue can take weeks. Trauma to the brain or central nervous system can be irreversible. But with nanomedicine, a nanoparticle-infused hydrogel could heal brain and bone injuries by creating new blood vessels and encouraging stem cells to replace dead tissue. Developed by scientists from Clemson University, the gel still needs several more years of animal testing before human trials can begin. Injuries involving nerve damage or the spinal cord are among the most difficult to treat. But nanotechnology could open the door to rebuilding damaged nerve cells. Although regenerating nerve cells is the ultimate goal, researchers have so far been able to develop the scaffolding necessary to rebuild nerves following damage. The technique, a nanotechnology-infused stem cell treatment developed by David Nisbet of Monash University, could also aid in the treatment of Parkinson's disease.
Besides treating immediate injury, researchers are also exploring uses of nanotechnology to fight the effects of aging and to promote longer life. By using a breakthrough nanogel to stimulate stem cells, Northwestern University scientists found that they can regenerate lost cartilage in joints. As adults age, they start to lose their cartilege, a painful condition for which there is little effective treatment. A separate study undertaken by researchers at the University of Central Florida (UCF) found that using an industrial nanomaterial, they can triple or even quadruple the lives of brain cells. This could lead people "live longer and with fewer age-related health problems," according to a UCF press release about the study.
With more than an estimated 1.5 million new cancer patients this year alone, it's no surprise that one of the more promising applications of nanotechnology is in the detection, monitoring and treatment of various forms of cancer. From targeted drug delivery to direct attacks of "nanoworms" on tumor growths, researchers working within the field of nanomedicine are using the technology to attack cancer cells with unprecedented precision.
WATCH: NANOTECH RISKS
It's a tall order: make a material that conducts electricity, stretches like rubber, expands and contracts when hit with electric current, and is clear as glass. There have been many attempts, but they've all fallen short.
Now a Harvard University team has done it by combining a transparent hydrogel with a conductive polymer that behaves like a motor. The work could lead to artificial muscles, transparent loudspeakers and power sources that generate electricity when squeezed or stretched.
The study, led by Zhigang Suo, professor of mechanics and materials, appears in this week's journal Science.
"Suo and his team combined, in a very clever way, two known things," said John Rogers, a materials science professor at the University of Illinois, who has done extensive work on flexible, implantable devices. "The result -- a transparent, artificial muscle -- is something that is new, and potentially important as a technology for noise cancelling windows, haptic display interfaces, tunable optics and others." Rogers was not involved in this study.
Stretchable electronics have been made with networks of ultra-thin metal wires, embedding stiff conductive "islands" of electronic components in stretchable sheets, or by using carbon nanotubes. Some research teams have tried mixing polymers with metals. But none of these approaches has been ideal. They are not as flexible or conductive as materials scientists would like.
The Harvard team managed to make a conducting material that stretches as much as good rubber, up to five times its length.
To make the hydrogel, Suo and his colleagues combined a chemical called polyacrylamide with salt water. In the mixture, the polyacrylamide molecules formed a lattice, and the salt ions, which conduct electricity, occupied the open spaces. One surprise was the conductivity -- it was about as good as a typical touch screen. "Typically an ionic conductor like this is several orders of magnitude lower. They were written off as viable conductors," Suo said.
Two major advantages of ionic conductors are that they are very stretchy and completely transparent.Eliza Grinnell, Harvard SEAS Communications
Next, they put a thin layer of the hydrogel, just 100 microns, on both sides of a piece of elastic adhesive mounting tape.
Essentially what they created was a three-layer "sandwich," with the tape serving as an insulating material sandwiched between the two conducting layers of hydrogel. Next, the researchers attached a copper electrode to each end of the sandwich.
When they ran a current through the electrodes, the sheet expanded and contracted, depending on how much voltage was applied.
This is just the way muscles work; an electrical signal from the nervous system goes to a muscle and causes it to contract or expand. And it's also how speakers make sound. In both cases, current is causing the material to change shape.
In one experiment the scientists attached the other end of the electrodes to a music player and added a current. The rubber sheet vibrated, just like a speaker diaphragm.
If the polymer sheet was squeezed or stretched, either by pinching it or when it vibrated in response to sound, it also generated a small current -- just like some types of condenser or ribbon microphones do.
Suo suggested that the transparent sheet could work as an active noise-cancelling layer on windows. The vibrations from loud noises would make the hydrogel generate an electric current, which could be be used to produce another signal to cancel out the sound.
"We're all, evidently, excited about the possibilities," Rogers said.