Skin is a material with astonishing capabilities: the flexible, waterproof layer constantly regenerates itself, heals itself after scratches and cuts, and, through its nerves, conducts electricity, relaying the sense of touch to the brain. Engineers have long been trying to come up with a synthetic polymer that does all those things, and does them under standard conditions rather than the carefully calibrated set-up of a lab. Now engineers have created a polymer with a combination of skin’s most elusive attributes that no polymer had achieved before: This new material, reported in Nature Nanotechnology, can conduct electricity and, when it is sliced open with a razor, can heal itself at room temperature.
Listen to this: Scientists, experimenting with guinea pigs, have used the electrical potential of the inner ear to power a 1-nanowatt wireless radio transmitter.
The cochlea, or inner ear, converts the mechanical energy of sound into electrical signals to the brain. The electrical potential in the ear comes from the difference in concentration of potassium ions in fluid separated by membranes in the inner ear, creating the equivalent of positive and negative poles of a battery. To this cochlear battery, researchers hooked up a wireless radio transmitter, with a power of one nanowatt, one billionth of a watt (for reference, a typical lightbulb is 60 watts), which radioed a measurement of the ear’s electrical potential to the researchers, according to their report in Nature Biotechnology.
If you’re reading this with a laptop sitting on your legs, you might have noticed that computers tend to warm up as they work, turning electrical energy into thermal energy. In fact, two-thirds of all the energy we use is lost as waste heat. Maybe, instead of just using the heat from your computer to keep your lap toasty, we should be harnessing that heat by turning it back into electricity. But the thermoelectric materials that convert thermal to electrical energy aren’t very good at their job. While they have some applications, the expense and inefficiency of current thermoelectric materials make them impractical for implementing at a large, power-saving scale. Until now: a new thermoelectric material might finally let us recover the energy lost to waste heat—at a reasonable price.
What’s the News: We’ve all fantasized about a cell phone battery that won’t quit. Now scientists hoping to harness the power generated when you walk are developing a device that might eventually use your footfalls to power small electronics. But will it overcome the hurdles of efficiency and cost?
Georgia Tech researcher Manos Tentzeris holding
up one of his inkjet-printed antennas.
What’s the News: With all of the electronics cluttering our daily lives, the air is abuzz with ambient electromagnetic energy from sources like cell phone networks, radio and television transmitters, and satellite communications systems. Now, researchers at the Georgia Institute of Technology have devised a simple, cheap way to harness that wasted energy: capturing it with inkjet-printed antennas and storing it in batteries.
What’s the News: In high school physics classes, students are often taught that static electricity develops when electrons detach from the surface of one object and jump to another, causing a difference in charge. Since opposite charges attract, the two objects are drawn to one another (like your hair to a balloon). But new research published in the journal Science shows that static electricity is caused by more than just the exchange of individual electrons, and instead involves the transfer of bigger (yet still tiny) clumps of material.
What’s the News: Metamaterials could improve wireless power transfer, letting us one day charge our devices without the hassle of cords and wires, says a study published last week in Physical Review B. While wireless power transfer already works to for tiny amounts of energy, metamaterials could theoretically be used to safely and efficiently boost the technique to handle more power, such as microwaves and lasers.
What’s the News: Scientists have created the first rechargeable battery that uses seawater and freshwater to generate electricity. If installed into every ocean-discharging river in the world (that’s not a realistic scenario—just a frame of reference), the process could produce 2 terawatts, or about 13% of worldwide electricity use. As the researchers write, this battery is “simple to fabricate and could contribute significantly to renewable energy in the future.”
How the Heck:
What’s the Context:
Not So Fast:
Next Up: Noting the limited supply of freshwater on Earth, lead author Yi Cui says that “we need to study using sewage water … If we can use sewage water, this will sell really well.”
Reference: Fabio La Mantia et al. “Batteries for Efficient Energy Extraction from a Water Salinity Difference.” Nano Letters. doi: 10.1021/nl200500s
Image: Nano Letters