字幕表 動画を再生する 英語字幕をプリント Since the early 1900s, researchers have been working on ways to turn radioactive material into an electric current that lasts.. for decades. Yeah, that's right. We're talking about nuclear batteries! This class of batteries is known as betavoltaics, and they're powered by the beta-decay of a radioactive material—hence the name. Beta particles are basically just high-energy electrons, so setting a beta-emitting material up next to a semiconductor is virtually all you need to get an electric current in motion. Though their power output can be pretty low (we're talkin' less than an AA battery), they last as long as it takes the material to decay. And since radioactive materials can have half-lives of centuries to millennia, that means batteries that could last for decades without any noticeable power loss. As an aside, betavoltaics are different from the Radioisotope Thermoelectric Generators (or RTGs) that NASA uses for space missions. Those are powered by the HEAT of radioactive materials, like plutonium, instead of beta particles directly—and are also sometimes referred to as nuclear batteries. But betavoltaics can be made smaller and safer than RTGs, and with the incredibly long lifetimes that nuclear promises. Back in 1954, the Radio Corporation of America announced the development of their first betavoltaic battery. And at the time, it was a big deal. RCA imagined them being used in wristwatches, hearing aids, and radios. And in the February 1954 issue of LIFE magazine, RCA even compared their invention to Edison's lightbulb. But, while lightbulbs are literally everywhere, I would wager you probably don't own a device that runs on nuclear batteries. Today, betavoltaics are mainly used in deep space and military applications- far away from the average consumer. And there are a lot of factors involved as to why that is, but a big one is safety. Like I said before, betavoltaics are safer than other nuclear power systems, but some beta-emitting materials can still be pretty dangerous. For example, RCA's prototype from 1954 ran on Strontium-90, exposure to which can cause leukemia. And even though their battery was coated with radiation blocking materials, it still probably wasn't the safest thing to hand off to anyone walking down the street. But we've come a long way! In recent years, several research teams have been looking for a way to safely harness the power of betavoltaics. And one team at the University of Bristol is making one out of DIaMonDZ! We talked to Dr. Neil Fox, who's developing a new prototype made out of carbon-14, a naturally-occurring radioisotope that's in our atmosphere and in all living things.. It's also a common nuclear power plant waste material. [Dr. Neil Fox ] “So our research has really been about looking for ways to repurpose that material, so that it effectively can be recycled. And carbon-14 is a particularly attractive one because it's not really on the list of really nasty radioisotopes. It's a fairly, friendly material to work with..” Fox's team isolated Carbon-14 and synthesized a diamond out of it. In doing so, they created a radioactive diamond that could produce an electric current(!!). Granted, it's a small one- not enough to power your phone. But it IS enough to power smoke detectors, emergency signs, IoT devices, sensors in jet engines or deep sea cables, and even e-readers. And it could power all of those things for decades, without needing to be replaced. As for safety?-- [Dr. Neil Fox] “It is totally safe because we're talking about a device which is made of diamond. The radioactive part is actually diamond as well And all of the radiation, all of the power of the device is completely absorbed by the diamond structure around it.” But perhaps one of the most impactful applications of this battery is for medical implants. Today, they largely rely on lithium ion batteries, but those have limitations. [Dr. Neil Fox ] "I mean there's some little girl, she has to have some fairly intrusive surgery on her hearing implant every 26 days they have to change the battery on this thing… We're constantly getting emails from people who've got all sorts of implants…So if you can provide them with a solution where it's fitted to last for decades, even for a lifetime, that's got to be worth something." So, today's nuclear batteries might not be what scientists imagined back in the 1950s, but a nuclear diamond battery that could go inside you? Still pretty dang cool if you ask me. For more on the science of batteries, check out this playlist, and let us know down in the comments if there are any other battery topics you want us to cover! As always, thanks for watching, and I'll see you next time on Seeker.