MATRIX PowerWatch - TEG powered smart watch

[ChristopherN]

Just found this: https://www.indiegogo.com/projects/smartwatch-powered-by-you-matrix-powerwatch-watch-fitness#/comments

Looks interesting, and might be possible, but I'm skeptical if it's really worth the effort. The power output will differ a lot based on the user geo location and usage patterns.

A Pebble runs for about 7 days, a Withings Steel for up to 8 months. I guess this thing is somewhere in the middle, it has a somewhat fancy display but lacks power hungry features such as live notifications and heart rate tracking.

One interesting thing to note is that this project seems to be in cooperation with Arrow.

[Koen]

https://www.cnet.com/news/matrix-powerwatch-no-charge-claims-to-last-on-body-heat/
It's a shame they couldn't leave a final prototype to the writer for a few days/weeks for him to confirm its qualities. It includes a picture of its current prototype and "somewhat fancy display".

Anyway, you might be interested by Seiko "Thermic" and Bulova "Thermatron".

[edavid]

Scam.

1. It's not possible to manufacture a fancy watch case like that for $100K

2. They can't produce enough power (they even admit it would have a battery inside)

3. You can't measure calorie use that way, and their handwaving over the subject is pathetic

[EEVblog]

Haven't even watched the video and this raised a reg flag with me straight away.
Most smart watches get battery life measured in weeks.
Would be interesting to run the numbers on this one.
Granted though, the extremities of the body like the hands and arms are used by the body to radiate heat during high intensity workouts.
I suspect this will be a turkey if you don't exercise hard every day.

[EEVblog]

http://www.gizmodo.com.au/2014/04/the-cool-promise-of-machines-that-run-on-body-heat/

[rollatorwieltje]

Haven't even watched the video and this raised a reg flag with me straight away.
Most smart watches get battery life measured in weeks.
Would be interesting to run the numbers on this one.
Granted though, the extremities of the body like the hands and arms are used by the body to radiate heat during high intensity workouts.
I suspect this will be a turkey if you don't exercise hard every day.

Seiko and Citizen made watches with a TEG in them, they were barely able to power a regular quartz movement. They want to run something with a Bluetooth radio built in...
I wear a stainless steel automatic watch, after a few minutes on the wrist it feels pretty much uniformly heated up. Would be nice to take a look at it with a thermal camera, don't have one myself unfortunately.

Also what's the point of a step counter (this "smart"watch actually doesn't seem very smart) when you're exercising... When you're exercising you're probably not the target audience for a step counter

[EEVblog]

Seiko and Citizen made watches with a TEG in them, they were barely able to power a regular quartz movement. They want to run something with a Bluetooth radio built in...
I wear a stainless steel automatic watch, after a few minutes on the wrist it feels pretty much uniformly heated up.

This thing likely relies on
a) Serious exercise (likely daily)
and likely also
b) Movement by way of airflow. i.e try using it on a stationary bike and watch the efficiency drop.

They say in the video they have a ton of data that proves it work, which of course they don't show.
Of course it works, so does the Batteriser and uBeam, but the devil is in the practicality.

[matrixindustries]

All,

Not much I can say here off the bat that will convince you since you seem like hardcore skeptics. I can offer a visit to any of you that are interested in learning more about our TEG technology to drop by our lab. You can see a watch build for yourself and other demos we have setup.

Otherwise, I'm happy to answer questions if you're interested.

Thanks.

[ChristopherN]

Hi matrixindustries,

thanks for replying here.

We're all technical people / EEs and like data better than marketing.

Could you provide some real-world test data?

For example:
-TEG power output over a "normal" day with data points for skin temp, ambient air temp, case temp, airflow, ...
-Power usage of your watch in its different operation modes like display only, BLE active, BLE RX, BLE TX, ...
-An output diagram that shows ideal conditions.

Don't get me wrong, I get that this may be confidential information. However, I guess you could silence all critics pretty soon if you provide some hard data. The technology behind this would be very interesting for other applications such as wireless sensor networks.

Thanks
Christopher

[Corporate666]

All,

Not much I can say here off the bat that will convince you since you seem like hardcore skeptics. I can offer a visit to any of you that are interested in learning more about our TEG technology to drop by our lab. You can see a watch build for yourself and other demos we have setup.

Otherwise, I'm happy to answer questions if you're interested.

Thanks.

Wait, that's not an appropriate reply at ALL.

Dave above raised a very good point.  You don't mention anywhere in your campaign what parameters this watch requires to work.  Engineers are going to assume there will need to be a substantial temperature differential which could only come about if you were in water, or on a bicycle, or running at a fast rate.

But it doesn't say that anywhere in your campaign, and in the absence of that, non-engineers will look at your campaign page and assume that they can just strap this watch on and their body heat will power it.

So what is the answer?  What level of movement is required in order to make the watch operate?  You need to give an honest answer on this, without hedging or evading.

[hayatepilot]

This is total BS.
They want go generate power with the heat flow from your wrist to the ambient?
Lets do some calculations:
The human body loses about 80W through the skin and the surface area of the skin is about 2m². This gives you 8mW/cm² of heat flow per area. Not too bad.
But the efficiency of thermoelectric generators is VERY bad.
They achieve about 10% of the carnot efficiency which is \( \eta=1-(Tc/Th) \) . With 10K temperature difference this yields a total efficiency of 0.33%
With the surface area of the wrist of about 40cm² (very generous) you could expect about 1mW of electric power.

But remember, this is under ideal conditions. If you wear long sleeves, the temperature gradient drops to almost zero and so does the power.
Maybe it is enough for a normal watch, but not a smartwatch with bluetooth, etc.

I would test the power output if I had a peltier element. I bet you it is almost not measurable.

Greetings

[EEVblog]

The human body loses about 80W through the skin and the surface area of the skin is about 2m². This gives you 8mW/cm² of heat flow per area.

It's going to be much better than that during hard exercise. They body literally shunts masses of blood to the arms in order to cool the body down.

[EEVblog]

Not much I can say here off the bat that will convince you since you seem like hardcore skeptics. I can offer a visit to any of you that are interested in learning more about our TEG technology to drop by our lab. You can see a watch build for yourself and other demos we have setup.
Otherwise, I'm happy to answer questions if you're interested.

Thanks for joining 
No need for questions, just show us the "tons of data to prove it works" as you said in your video. Real data. Don't dumb it down, give it to us raw if you like, we are engineers here.

[EEVblog]

Not much I can say here off the bat that will convince you since you seem like hardcore skeptics.

And what's wrong with engineers being skeptical about a product that is hyped to the hilt and that claims to do something well beyond what other companies have achieved in the past, and make those claims without a single scrap of engineering data to back it up? Of course engineers who know about these things are going to be skeptical, what did you expect?
Extraordinary claims require extraordinary evidence.

[EEVblog]

And their "Certified by Arrow Electronics" sounds impressive until you read what it actually means:


Arrow just verify that they can get the parts, not that it in any way meets it's performance clams.

[EEVblog]

And bingo, here's the crux of it:

The watch goes into low-power sleep mode when not being worn. According to Tham, once it's charged it could last in high-power mode for two years, and in a sleep state "for decades." Of course it sounds too good to be true, but the Matrix watch's Indiegogo campaign is live and kicking, and Matrix intends the watch to ship next summer for $160.

So it can run for TWO YEARS on the internal battery 
So why not just stick an ordinary battery in it? or charge via USB? Because, well, marketing.
The TEG part of it is a nothing more than gimmick in this case.

[EEVblog]

500uW power generation during exercise.

We can now make some calcs:
- Assuming that's 500uW available to charge the battery during exercise in their best case conditions. (Ignoring DC-DC losses)
- Guessing 1/5 of that during rest, or 100uW. Could be much lower or zero, but hey.

Then:
- Assuming 1 hour of exercise a day for an active person, that's 0.5mWh.
- Assuming 15 hours wearing the watch at rest, that's another 1.5mWh
- Nothing for sleeping because it'll either be off, or under or against a sheet/blanket/pillow etc and will surely reach thermal equilibrium and not generate anything.

So that's at best maybe 2mWh a day of generation.
Let's say the micro and screen and whatnot takes 20uW, so subtract 480uWh takes us back to 1.5mWh a day.

A single CR2032 is about 600mWh capacity, so assuming you exercised 1 hr every day for 365 days a year under ideal conditions (they said  "cold, windy day"), that would be the equivalent to 400 days worth of a single CR2023.
Given this is all ideal, double that number as a ballpark. 800 days.

Conclusion: The TEG charging looks to be nothing more than a gimmick.

[Bud]

I do not go to gym but do people really wear watches in the gym? Id think there is possibilities to damage it plus all that sweat and smell. I would not want my watch stink.

[rollatorwieltje]

I do not go to gym but do people really wear watches in the gym? Id think there is possibilities to damage it plus all that sweat and smell. I would not want my watch stink.

Plenty of watches with sport related features, i.e. heart rate, speed, stopwatch etc.
Watches have been water tight since roughly the 1940's. I wouldn't recommend a leather strap when you sweat a lot, but pretty much anything else is fine. Just give it the occasional wash.

[hayatepilot]

There was a conventional thermoelectric watch: The Seiko Thermic.





I've read that it didn't work that well in summer or in tropical regions, since the temperature difference is too small.
Not to mention a conventional watch movement uses only about 1.5uW .

I think one could generate more energy using mechanical rotors (like in automatic mechanical watches) or solar cells at lower cost.
Thats probably the reason they don't make any thermoelectric watches anymore but there are plenty of kinetic and solar watches.

[matrixindustries]

All,

There's absolutely nothing wrong with being skeptical, but the characterization is that we're a bunch of fly-by-night marketers. The team has between 5 and 13 years of thermoelectric experience. We're a bunch of geeks like you guys, PhDs in EE, Chemistry and Materials Science.

The Arrow certification was important to us to quiet the skeptics. They reviewed the entire circuit diagram. It was not just a bill of materials scan.

BLE radio obviously requires a lot of current, and that's where the internal battery takes over. Otherwise, your body heat is generating the power for the watch. That being said TEGs can light up LEDs when designed right.

I'm obviously not going to change minds here and so I won't even try. My offer still stands that if any of you want to visit our lab and see a watch build from the bottom up or any of our other energy harvesting demos, you are welcome to. That's probably the only way for you to be convinced that this tech is for real.

[edavid]

How about if you tell us what this means:

Accurate Calorie Count

Your body turns the calories you consume into heat. The PowerWatch accurately measures the calories you burn using our advanced thermoelectric technology.

[Fred27]

The Arrow certification was important to us to quiet the skeptics.

I'm obviously not going to change minds here and so I won't even try.

These two sentences pretty much indicate it's rubbish. You shouldn't be trying to quiet sceptics, you should be confident that you can change their minds. I'm sure everyone here is happy to admit they're wrong given some data to support your claims.

[Artlav]

Just did a quick test.
A 40x40 mm TEG module with a radiator on the other side produces about 200uW after sitting on the wrist for a while. The room is at 24*C.
Sounds like about the right ballpark.

Tried to measure the skin temperature, but the thermal camera shown more or less rubbish at the absolute scale. Realtively, the spot under the TEG was 2*C colder.

[Bud]

The Arrow certification was important to us to quiet the skeptics. They reviewed the entire circuit diagram. It was not just a bill of materials scan.

Can you please point us out to Arrow's certification service offer description. If such exists i am sure i can find it but with your help it will save me time since you went through it.