iFind - another moot energy harvesting gadget

[Bud]

I know people here love energy harvesting topic. So not sure why this one was able to escape this forum's attention

https://www.kickstarter.com/projects/yuansong84/ifind-the-worlds-first-battery-free-item-locating

It is a battery-less locating tag and the claim is it harvests energy from wherever and connects via Bluetooth to the smartphone. So the idea is you fire up an app on the smartphone and the tag will start beeping (yah, with no battery) so you can find your item the tag is hooked to.

I find (no pun intended) several claims seem hard to believe. How about 200 feet (60m) working distance on Bluetooth  AND beeping, all with no battery. How about all this being squeezed in a tiny 32 x 27 x 2.4mm plastic case, and where the heck is an opening for the beeper, and if there is one, how the tag can be made waterproof as claimed. Strangely,  the video shows the tag been put in a wallet compartment, which would muffle the beeper and make it unusable , which would defeat the purpose. Also not sure why a "flex circuit" would be needed for something that is going to be put inside a flat casing. How about their stretch goal to "customize any range distance". How about flat $10 international shipping that includes taxes and fees and a tracking number - makes me wonder if these guys ever shipped anything internationally. Also, "have negotiated contracts" with shipping companies without even having the goods manufactured? The list goes on and on...

[daveshah]

They've probably hidden a CR2016 in it, so it works long enough for buyers to be happy.

[Harvs]

I wouldn't be so quick to write this one off. 

I haven't read through it properly (in fact given it not much more than a cursory glance), however the fact that its got a Professor, a Ph.D candidate and another Dr. not sure if medical, that have a few publications between them putting their name to it (assuming they really are.)

http://scholar.google.com.au/citations?user=kpQGGFUAAAAJ&hl=en&oi=ao
http://scholar.google.com.au/citations?user=pxFyKAIAAAAJ&hl=en&oi=ao

Whilst this doesn't give them any specific domain knowledge per se, it would seem a stupid move for them to fully put their names to it if they weren't pretty damn sure they could pull it off.

[EEVblog]

Even if it is technically possible, that does not make it practical.
The thing has to continually receive data, and that means it needs a continuous supply of harvested energy to do that, not to mention transmitting.
The mechanism is not explained, probably piezo-electric, in which you might be able to use the buzzer as the harvesting element?
Thermal harvesting? Nope, too small for that.
Solar? Nope, though that moulded plastic case.
Then there is RF harvesting, but it's seems way too small for that, I've busted the practicalities of that one before.
My best guess is that to be practical as described it would have to harness the bluetooth signal from the phone itself. I haven't ran the numbers on that, but off the bat I'd call BS on that right away.
Doesn't leave much...
Also, no poof that the item shown is actually a working prototype. Could very well be just a dummy case, and I'd bet money on it actually.

[EEVblog]

Scratch that. It is EM harvesting technology:

To begin with, iFind tag doesn’t have a battery. Instead, it uses our patent pending EM Harvesting technology and stores the energy in a uniquely designed power bank. In other words, iFind tag powers itself. In the worst case scenario, let’s say you lost your tag in the middle of a remote desert, where there’s no EM wave at all, the tag will still hold power for days.

That implies that it's not harvesting the bluetooth energy, but other general EM radiation. Once again, it comes down the physics I explained in a previous video on this stuff.
Without running the numbers, I call possible, but impractical.
It's got to fire up that receiver every few seconds, so it's continually draining any piss-ant EM energy it is able to harness.

[EEVblog]

Yep, general EM radiation:

I’m wondering if I can check the charging level of each tag?

You don’t really need to worry about this. In everyday environment, the Wi-Fi transmitters, cell-phone antennas, TV masts, and so on will keep it charged, so it will never die. And Yes, you can check the charging level in the iFind App.

Having such a broadband range means they can't design a wizz-bang efficient fractal antenna either.

[EEVblog]

https://www.wetaginc.com/good-true-tour-ifind-battery-free-feature/

[bookaboo]

Scratch that. It is EM harvesting technology:

To begin with, iFind tag doesn’t have a battery. Instead, it uses our patent pending EM Harvesting technology and stores the energy in a uniquely designed power bank. In other words, iFind tag powers itself. In the worst case scenario, let’s say you lost your tag in the middle of a remote desert, where there’s no EM wave at all, the tag will still hold power for days.

That implies that it's not harvesting the bluetooth energy, but other general EM radiation. Once again, it comes down the physics I explained in a previous video on this stuff.
Without running the numbers, I call possible, but impractical.
It's got to fire up that receiver every few seconds, so it's continually draining any piss-ant EM energy it is able to harness.

I don't think it needs or has a receiver, just a transmitter I've only ever dabbled in bluetooth but roughly speaking rf power of off the shelf modules is 1-5mW. I'm not sure of the efficiency of their rf module but from experience with 433Mhz ~15mA @5v (75mW) of battery power gets you 10mW rf power (again an off the shelf module ymmv).

Now if we take a shot in the dark at what their actual transmit mW consumption would be what would you guess?

The thing is their duty cycle could be something ridiculously low too, especially if they have written their own protocol. There's no reason they couldn't transmit for 50mS every 10 seconds.


Whether any of that is enough to make EM harvesting practical I still don't know. It certainly ticks all the boxes for a successful scam project but I can't help wondering.

[Rufus]

Without running the numbers, I call possible, but impractical.

I call impossible. They might be able to harvest enough energy to burst a few ms of rf transmission now and then but no way could they get enough to sound a 'loud alarm' for more than a couple of peeps from a supercap and then wait an hour or two to charge up again.

I tried to find some figures without much success. It looks like a typical domestic environment has a few nW/cm^2 rf energy density (more if close to an active wifi node or within a few km of a broadcast transmitter).

That means the energy to drive a 'loud alarm' with a few mW for 1 second is going to take something the size of this tag more than a week to collect.

[yramgu]

Maybe if they pinged out serial number + battery level say once a minute at a high bit rate so that the transmission time was low... Problem is then you only get one ping per minute, not ideal for locating something. Okay, let's say they somehow got it down to once every 10 seconds, for the sake of argument. This is Bluetooth, so 2.4GHz, crap range at low power. The only way to determine distance is signal strength, but obviously that will vary depending on the environment. If you put it in a box you could be right on top of it but getting a very low signal. Anything metal will block it, most walls will give it severe problems.

Nah.

Spot on. You'd need a transmission every few seconds to have a good "comfort of use". If they're looking at 60m range with Bluetooth and a typical Smartphone as a receiver (i.e crappy receiver), they'll need ~+10dBm radiated power. Considering a poorly integrated antenna and bad environment (pocket/wallet..), the chip would need to output something like +16dBm to compensate. Not really negligible in terms of current..

[max666]

But, but, what if you loose your phone?   

But seriously, I call it BS too, or at least several points are grossly overestimated. 60 m range with Bluetooth that uses even less power and a "loud" buzzer?
And I like how they say it’s "biodegradable"! Seriously?!

[Bud]

But, but, what if you loose your phone?

You did not read the whole thing!... Ready? :

"...you can locate your phone by shaking any of your iFind tags — No more frustration"

[yramgu]

"...you can locate your phone by shaking any of your iFind tags — No more frustration"

Didn't see that. Nice one!^^

[pickle9000]

"...you can locate your phone by shaking any of your iFind tags — No more frustration"

Didn't see that. Nice one!^^

I like the 2 way key finder idea. A Chinese company should start cranking them out, with batteries of course.

[Rentium]

A similar product, but with a battery.
https://www.indiegogo.com/projects/sticknfind-bluetooth-powered-ultra-small-location-stickers

And according to the comments, it doesn't work as advertised, even with a CR2016 battery.

Also they claim in the FAQ:
"Is there any Visual alerts for people with hearing issues?
Yes, the iFind App does have a visual locating display showing the estimated direction and distance."

I thought you couldn't determine the direction of a Bluetooth signal, or am i wrong?


(BTW, my fist post  )

[grumpydoc]

I thought you couldn't determine the direction of a Bluetooth signal, or am i wrong?

In the general case probably not but with an electrically steerable antenna you might be able to.

Or..... put GPS in both devices and work out the direction vector.

[Rentium]

I don't think i know any phone with an electrically steerable antenna  .

I doubt they can power the Bluetooth module without any issues let alone power a GPS module long enough to get signal and position (and then send the said position to the phone).

[grumpydoc]

No, I don't think I've heard of a phone with a steerable antenna either - sounds like a good way to reduce power consumption though, if you could concentrate the phone's transmit signal in the general direction of the mast.

[miguelvp]

If you can calculate the distance to the object via bluetooth and you are moving around you can figure out the general direction by using the phone's accelerometer. Shouldn't be too complicated.

But in my house we don't need an iFind, i'm the iFind of the house

And yeah, my wife is terrible leaving things all around and never remembering where she left them, but I have a good visual memory.

[Rentium]

Yes, you're right, i wonder if Multipath propagation is a issue there, especially in a room (surrounded by walls).

There's a case for the iPhone with a similar claim to energy harvesting
https://www.kickstarter.com/projects/concepter/lunecase-bring-the-back-of-your-iphone-to-life
Seems like it could be done. There's much more space inside the case for an antenna and it only powers a few led's once in a while. Opinions?

[yramgu]

Yes, you're right, i wonder if Multipath propagation is a issue there, especially in a room (surrounded by walls).

There's a case for the iPhone with a similar claim to energy harvesting
https://www.kickstarter.com/projects/concepter/lunecase-bring-the-back-of-your-iphone-to-life
Seems like it could be done. There's much more space inside the case for an antenna and it only powers a few led's once in a while. Opinions?

They say it only works with GSM. Seriously?! In 2014?
Anyway here's how it goes down:

1 - The case will have an antenna inside. This antenna will have to be tuned to GSM in order to detect messages, etc... as they claim. So essentially it will work in the same bands as the phone's antenna.

2 - That antenna will be very close to the phone's antenna and thus will load it and detune it. And it will detune the phone's antenna on the whole range of frequencies, not just GSM.

3 - Let's say, for the sake of argument, that the phone has an automatic antenna tuner (I don't know if the Iphone has one). It will then re-tune your antenna. BUT: the radiation pattern will be modified nonetheless. Smartphone antennas are designed to have a specific radiation pattern when the user has the phone against the head (making a call) so that the communication quality is improved. So this casing will most likely deteriorate your phone's ability to communicate.

4 - The phone will sense this deterioration (it's a smart phone) and will retaliate by cranking it's Power Amplifier. Aaaaand you will see your battery life melt like snow under the sun. The end.

They say they've tested it and haven't seen any deterioration in the phone's performances, but i'm really skeptical. And their timeline looks like complete BS.

I'd love to stand corrected because honestly it would be a really cool gadget!

[Rentium]

Agreed,
Theres one more dodgy point:
"The Lunecase will identify the type of notification, whether it would be an incoming call, or a text message."
How can it detect if it's either a message or a call only using the GSM capture thingy. Is it the emission power? Don't think so because it would go bananas if someone starts browsing the WEB using mobile data. And if it has any kind of bluetooth interface with the phone, it would imply much more power consumption in the phone, and in the case itself (Need to have bluetooth on all the time, and the bluetooth module in the case itself is going to need power).

[yramgu]

I have no idea. In GSM, each carrier frequency can bear up to 8 users, and the carrier is shared between users by Time Division Multiplexing. The phone gets its time slot from the base station so that it knows which messages are addressed to it or not. But the casing would have no way of knowing that 
With the sole emission power/spectrum you wouldn't be able to differentiate voice from sms. Maybe the answer doesn't lie in the physical layer of the protocol?

Anyway it doesn't look promising^^ (and yeah BT couldn't be a viable option)

[corrado33]

Just one more quick issue with these "low power bluetooth" devices.

They don't work with all phones. Only phones with comparable low power bluetooth in them. For instance, they will not work with my iPhone 4 or my girlfriend's droid razr maxx. She bought that phone last year, so it's not nearly as old as my iphone. (I've looked into this issue before, she tends to lose things so I was shopping for this exact thing a while ago.) Now, this issue will become less and less in the future, but it's something to think about. And I know I keep my phones for a long time, but this issue generally isn't mentioned. They say "apps for android and iOS" but you don't find that they require specific devices till you dig deeper!

[Bud]

Hallelujah! Some technical data was released:

https://www.kickstarter.com/projects/yuansong84/ifind-the-worlds-first-battery-free-item-locating/posts/862285

Hopefully it finally makes backers happy. All they need to do is to carry their favorite  WiFi device with them and blow +10dBm into their iFind tag every time it needs a recharge. Yah man, +10dBm, backers can safely forget about harvesting ambient energy.

Ah... seems backers are still not that happy, judging on the comments thread.