MIT Stealth Startup Charges Up Wireless Power Competition 63
gthuang88 writes: Wireless charging of electronics is an old concept, but there's a new player in the competition between companies like WiTricity, Energous, and tech giants Apple, Samsung, and Qualcomm. A new spinout from Dina Katabi's lab at MIT, called Pi, may have a new take on how to charge mobile devices at a distance. The company isn't talking yet, but Katabi's research suggests the system uses an array of coils to produce a magnetic field and detect when a device is within range, like a Wi-Fi router. The array can then focus the magnetic field on a coil attached to a phone or mobile device and induce a current to charge the battery. But it's still very early, and the field of wireless charging needs to settle on technical standards and work out its commercial kinks.
Re: (Score:2)
From the article itself, the device they mention has a range of "about a foot". I think it'd be pretty hard to get between the magnetic coils and the device they're charging.
Re: (Score:2)
I'll assume this technology is generally safe, but that it could interfere with medical devices or the like, which is another form of safety issue even if it's not a big deal for most people.
Re: (Score:2)
MRI machines are pretty safe, they have rip-your-jewelry-out-of-your-skin powerful magnets.
Magnetic fields don't hurt you
Here's a secret: the most powerful magnet on the Earth is the Earth itself.
Re: (Score:3)
Here's a secret: the most powerful magnet on the Earth is the Earth itself.
Ordinary bar magnets frequently have magnetic fields stronger than the earth's.
Re: (Score:2)
when you take into account the total volume of the field, its total energy is extremely large, much larger than any magnetic field generated artificially
Re:Safety (Score:4, Informative)
Unless you have a conducting loop in or around your body when it fires, such as a wedding ring, or a magnets in your body, such as are found in some medical electronics, or if you've got any accidentally embedded magnets such as those swallowed by children..
http://www.npr.org/sections/he... [npr.org]
Or unless there is a bulky, conducting metal object in the room, such as an oxygen tank:
http://www.nytimes.com/2001/07... [nytimes.com]
I'm not suggesting that a modest hom recharger will create such risks. But please, do not extrapolate armchair physics to assume you understand the real risks of a real electromechanical device without doing the research.
Re: (Score:2)
It's highly unlikely your wedding ring would happen to be just the right size to couple well with the field. If it did, it might get hot, prompting you to remove your hand from the vicinity of the charging station.
Re: (Score:2)
Thank you for pointing out that a small loop may not cause injury. A casual look at published guidelines shows that they say to remove _all_ metal, and some metal may be safe if designed carefully. But some guidelines accept that wedding rings, in particular, may be impossible to remove without cutting them and accept the modest risk. I'm looking particularly at this as an example:
http://www.mrisafety.com/Safet... [mrisafety.com]
So you've raised a very good po
Re: (Score:2)
MRI isn't the same thing as an inductive charger. The field is much stronger in an MRI scanner, and the main field is static. There are two dangers: having metal objects pulled by the strong static main field, and heating from the varying gradient fields during scanning. Non-ferrous metal generally isn't much of a problem, but if it's easy to remove you might as well. When I started doing MRI research we emptied our pockets but went into the scanner in our regular clothes, jean rivets, zippers, whatever
Re: (Score:2)
I very much agree with you. I'd not expect immediate, dangerous coupling from a relatively low intensity coupling such as a recharger might product, even if someone slept with such a device under their pillow and wore loop earrings.
It was the reasoning from viperidsenz that because MRI is safe, inductive recharging is safe that I meant to call into question. MRI, misused or accidentally mishandled, can cause injury and death. The scanners devices are not a good starting point for comparison of safety.
Re: (Score:2)
Magnetic fields don't hurt you
STATIC magnetic fields don't seem to hurt you. Time-varying magnetic fields most certainly can hurt you. In addition to ionizing radiation (x-rays, gamma rays) which can obviously hurt you, plain old radio waves can too [wikipedia.org]:
Radiation burns can also occur with high power radio transmitters at any frequency where the body absorbs radio frequency energy and converts it to heat.[1] The U.S. Federal Communications Commission (FCC) considers 50 watts to be the lowest power above which radio stations must evaluate emission safety. Frequencies considered especially dangerous occur where the human body can become resonant, at 35 MHz, 70 MHz, 80-100 MHz, 400 MHz, and 1 GHz.[2] Exposure to microwaves of too high intensity can cause microwave burns.
Re: (Score:2)
Federal Communications Commission (FCC) considers 50 watts to be the lowest power above which radio stations must evaluate emission safety
I wasn't aware these phone chargers would be more than 50 watts.
Re: (Score:2)
They may be, given the horrendous loss involved and the use of directional coupling. That 50 Watt limit is not absolute, it's more of a guideline for Amateur radio stations specifically, not all emitters. Your cell phone at < 4W is also closely regulated due to its proximity to human tissue. Please refer to the FCC RF exposure site [fcc.gov] for the full regs.
RF exposure is a function of frequency, duty cycle, distance, transmitter power, and antenna gain. I have a tiny 10mW 10GHz transmitter that couples its powe
200 times less field than your refrigerator (Score:3)
Your refrigerator, washing machine, and other household appliances run on inductive motors which use a thousand watts or so to generate electromagnetic fields strong enough to pull the magnets in the motor strongly enough to move 80 pounds of water and clothes. So those are electromagnetic fields in the kilowatt range.
Charging your phone requires around five watts or so. So the power levels, the amount of electromagnetic energy, is quite small - much smaller than the difference between a large washing ma
Re: (Score:2)
Motors use as small a gap between the stator and rotor as is mechanically practical for best performance and this minimizes magnetic flux leakage.
Re: (Score:3)
While Tesla did manage to transmit power wirelessly over a short distance, there is no evidence that he succeeded going further despite devoting a large part of his life to this problem.
However, we can thank Tesla for allowing us to light light bulbs from 100km... with wires. He can be considered the father of the modern power grid.
Cool but (Score:2)
If you can magically send power like this, why not just pylon up everything, protoss style?
Re: (Score:2)
Yeah, because all directed energy is harmful to flesh, right?
These are magnetic fields in the range of less than those generated by your fridge, if it was harmful, everyone in the first world would already be dead.
Yikes! (Score:1)
work out its commercial kinks
So would that be a straight BDSM dungeon, or are we going the whole way with specialists in urolagnia, acrotomophilia and menophilia?
Re: (Score:2)
work out its commercial kinks
So would that be a straight BDSM dungeon, or are we going the whole way with specialists in urolagnia, acrotomophilia and menophilia?
No way I'm looking those last two up at work.
Sounds expensive (Score:2)
AFAICS the only real way to extend range is by using very a very large set of coils for the transmitter ... I'm not sure if you can do this cheaply or efficiently.
I built a batteryless radio when I was 5 years old (Score:2)
Oh yeah, magic. Everything is magic nowadays.
Re: (Score:2)
You could charge a battery with a crystal radio. I doubt you could put in more power than the self-discharge of the battery you're trying to charge though.
yawn (Score:3)
this isn't even remotely new technology... and it fails for a lot of reasons.
1. you still need wires because the charging transmitters need to be plugged in and they only have a limited range so you're still going to be charging in roughly the same place.
2. The efficiency hinted at in there is horrific. I think its something like 20 percent in most cases and that's on top of the AC/DC conversion. So you lose 20~30 percent converting to DC and then you lose 80 percent of of the remainder transmitting it.
3. The cost of the systems usually isn't that bad but 30~50 dollars is still 30~50 dollars.
Re: (Score:1)
Re: (Score:2)
What doesn't work about them?
100 *.8 = 80 .2 = 16
80 *
It's the same fucking number. The only numbers I've seen for this over 50 percent require that the receiver basically sit right on top of the transmitter. I mean... literally on top of it.
At which point because the transmitter is plugged in... exactly how is this system wireless at all?
This is what I consider to be wireless power... like wifi or bluetooth. If your phone charges in your pocket because you just happen to be in an area with transmission... j
Re: (Score:2)
Getting to the point where there isn't a wire plugged into your phone allows you to design a phone with no openings. This allows the phone to be WATERPROOF. Thus solving one of the main causes of phone replacement.
Re: (Score:2)
waterproof cases already exist for about 20 dollars.
Regardless... no one using this tech is doing it for water proof cellphones.
If this is your best shot... we'll just leave it there.
Re: (Score:2)
Noone?
http://www.cnet.com/products/k... [cnet.com]
Failed!
I use it so I don't have to remove the waterproof cover from the USB port, I can just place my phone in a holder at home and it charges, and I place it in a stand in the car which charges it. So obviously, no one is the wrong word to use.
Please also, show me this mythical case you don't have to take off to charge your phone while it stays waterproof, without wireless charging.
Re: (Score:2)
your example doesn't use the technology in question and it is merely water resistant... something any phone could be with a water resistant case which are fairly cheap.
Jump in the discard pile.
Re: (Score:2)
Though the 3,100mAh battery has wireless charging capabilities, it cannot be removed (two screws on the bottom corners make sure of that). This may be inconvenient for those who like to swap out their battery often, but it does mean one fewer seam for water to seep through.
If you want to call it water resistant, that is up to you, but it isn't splash resistant, you can actually take it underwater and use it. Waterproof is just a term, but due to legal reasons, no one calls anything waterproof in marketing.
It has integrated QI charging, so it absolutely does have wireless charging. A water resistant case doesn't allow you to charge the phone as easily as dropping a phone on a charger, so it does not solve the problem, it just makes it 10 times harder to charge the phone whil
Re: (Score:2)
It isn't easier to charge.
In regards to the water issue... I can find a dozen imerisble cases that have a port on the side that permits charging.
And frankly I like the convienece of being able to use any USB cable to charge. Your QI idea only works with a QI charger which is going to be where with any reliability? Oh that's right... at your home an no where else.
How do you charge your stupid fucking phone at the office? Oh that's right, you need another QI charger which you'll buy seperately. Fantastic. And
Re: (Score:2)
My phone has a micro USB port like any other phone. I however have a QI charger in the car and house.
The freight train of fail would be on your end, not mine. Everyone does things your way, therefore there can be no other way. When I point out that you are incorrect, you try to derail what I am saying by coming up with all these convoluted solutions to something exceedingly simple and elegant. I would like to point out where this train started so you can see why you are the one failing at seeing the uti
Re: (Score:2)
your example contradicted your position. You're done.
I'm not going to respond to you again in this thread. You lost horribly.
Re: (Score:2)
Ha HA Ha HAHAHAHA
No, having an alternate charging possibility did absolutely nothing to contradict my position. If you think it did, you are more of a moron than I already think you are from this string.
Re: (Score:2)
Qi chargers that use an array of antennas to position the charging coil have been available for years. I have a Panasonic one and it works very well, just dump the device to be charged on it and it sorts everything else out. Efficiency is 70-80%, and it cost about 2500 yen (~£15).
The Nexus 5 charger uses magnets to align the phone with the charger. Either way works and is cheap. These guys missed the boat.
Re: (Score:2)
Did you read what I said? Of course you didn't. Why would you do that. It wastes time when you can just go into playback mode spitting out a lot of information and arguments I already dealt with.
1. How wireless is it if you have to plug the transmitter in and then your phone for example has to be put RIGHT ON FUCKING TOP OF IT. So yeah... sure... you don't have to put a cable into your phone. But how fucking lazy are you? There is still a cable right there right next to your phone. This is about as wireless
Re: (Score:1)
Re: (Score:2)
Good point. I think the best application I've seen of this tech was charging medical implants. That way you don't need to have breaks in the skin to permit charging. There is a receiver pad somewhere on the body and you wear a battery belt or something to keep the internal implant batteries charged.
So that's a good application. I'd hardly call it wireless. But at least it has a legitimate purpose.
Re: (Score:2)
There are lots of applications, the inability for you to think of them, is your problem.
You are the type of person who would have looked that the first computers and said, WTF? I can do that with my slide rule! And I don't have to plug it in. Computers are worthless and only makes sense in only a very limited set of circumstances.
Think cars that charge via coils in the road (or at stop lights, or your garage). Think of wireless mice and keyboards that charge off the desk they are on. How about being abl
Re: (Score:2)
Already you know what kind of man I am? From a few posts you say? You must have super powers. A psychologist couldn't tell what kind of man I am from anything less than several interviews. And even then I'd have to answer truthfully. If I intentionally misrepresented myself then not even the experts would classify me properly. But you figured me from a couple posts you think?
You haven't a clue what sort of person I am and this is not a new technology. Its been around since Tesla at least. To compare it with
Engineer Comments (Score:4, Informative)
I design near field low frequency RFID readers.
It's kind annoying to WiTricity claim they invented something (resonant charging) that the LF RFID industry has been doing for the last 30 years. ie Very HiQ coils to efficiently transmit to passive RFID tags (which also have HiQ resonant coils).
Magnetic fields can be well directed by permeable materials like ferrites, but as soon as you have to bridge the air-gap, you get 1/r^3 power loss. Can you do phased array effects like steerable antennas like the article claims? Yes, but probably not in a way that is beneficial to bridging the air-gap loss.
Here is a challenge. I give you 4 little round neodymium super magnets, and I'm going to let you rotate them into whatever static position you like, with the goal of producing twice as much magnetic attraction a distance 4x their diameter. Think you can do it?
Besides terrible efficiency you are also limited in power as described in ESTI EN 300-330-1
There is a specific allowance for magnetic near field from 119 to 135kHz of 70dBuA/m.
As for safety. These magnetic fields are fairly benign. We have thousands of these transmit at the legal limit on big 1200mmx600mm air coils, and have to our knowledge have not had an incident (ie with a pacemaker).
Re: (Score:2)
It can work if you're rich and don't mind raising world sea levels a few feet to wirelessly charge your electric car.
This is the WRONG focus (Score:2)
Focus should be on things like robotics, construction equipment, etc. Basically, the ability to beam energy 1 KM all the way up to 200 KM is a HUGE thing, and worth loads of money.
Re: (Score:2)
It does not mean that in the future a new, and better way will not be found.
In addition, wireless like I suggest here, would make a huge difference and be of great value.
Re: (Score:2)
So you have never lost a phone to the dreaded beast that is water?
Wireless charging allows waterproof design. It can be used for many things: wireless keyboards/mice, wireless charging of laptops, wireless charging of cars by the road, wireless powered sensors.
Re: (Score:2)
> It is easy enough to plug it in.
It's also quite awkward and destructive to the connector if any mistakes happen, and lugging around the cabling is awkward. It's hardly a new idea, "www.poermat.com" has been selling such stations for years.
Unfortunately, the customized charging case you have to keep the phone in for Powermat to work are quite expensive and make the phones unwieldy.
Efficiency (Score:3)
In a time where we are trying to get away from fossil fuels, aren't allowed to build nuclear power plants, have yet to solve storage for renewables and electric plug-in cars are a thing, do you really think we should make charging our devices less efficient?
Re: (Score:2)
Don't you know that efficiency has always taken a backseat to design and coolness.