15-year-old girl invents flashlight powered by the heat of your hand

http://www.extremetech.com/extreme/160003-15-year-old-girl-invents-flashlight-powered-by-the-heat-of-your-hand

by evo_9 • 13 years ago

386 121 13 years ago

extremetech.com

Architech0• 13 years ago

Sounds similar to the fiber optic cable material found @ Roswell, NM. 1947...

krapp• 13 years ago

Except the flashlight actually exists.

mbell• 13 years ago

Looks like she's just using the Peltier effect to power some LEDs. I doubt the flashlights would work well, if at all, at room temperature but would be useful in a cold climate.

ultimoo• 13 years ago

I'm not sure how it works but would having a small recess of water inside the flashlight help maintain the temperature difference? So that when you have used the flashlight enough that its temperature has risen to that of your hand, you can fill it up with water or ice and it'll cool down a little.

eksith2• 13 years ago

Yes, that's essentially the functionality of the flashlight, which makes it no less remarkable an accomplishment for someone her age.

I don't care about the use case or whether it works well. I care that it exists.

lotharbot• 13 years ago

" I doubt the flashlights would work well, if at all, at room temperature"

I found it a bit disappointing that they mentioned one use case as finding candles when the power is out, shortly after mentioning that it works only marginally at 50 degrees F. It takes quite a while for a normally-heated house to drop to that temperature.

It's a neat invention, no doubt, but the practical use cases for this particular version are going to be outdoors.

ISL5• 13 years ago

If the exhaust from a candle (think small, like a tea light) can be made to travel upward through the tube, and the exterior of the flashlight given sufficient heatsinking, it's possible that this arrangement can yield more visible light than the candle can produce.

I'd have to work through numbers to guess, and do the experiment to be sure...

ChuckMcM2• 13 years ago

Well the article does say that it works ok at 41 degrees and kinda sorta at 50 degrees. As with most things, its level of impressiveness varies with your understanding of the physics involved.

The interesting question for a science fair would be to see what she had learned of the science. Did she evaluate the efficiency of the Peltier device? (typically single digit percentages) Did she compute the amount of work you could do with different energy differentials? Coming up with the total joules available, versus the joules harvested? Did she look at the efficiency of the LED to convert energy into light. What is its lumens per joule rating, and given the choices did she look at single color light (say red) versus broad spectrum light via a 'white' LED (which is a UV led exciting phosphors to get different colors). Did she go over the various enhancement strategies (drop an ice cube in a hollow tube inside the light?).

And most importantly, given what she has learned about how one can convert a temperature differential into work, what other problems might she solve with that principle?

It is unfortunate that ExtremeTech goes for the link baitey angle "ooh a flashlight that works off body heat" and less on the "Hey if we teach kids real science, they can do stuff!" (which in my opinion is a better angle on the story).

kondor6c• 13 years ago

It's a great idea and a great science project, I just don't see how practical it would be due to how little light it would produce. Even if I kept it in the back of my car to aid in a possible road repair (perfect situation for a no battery device) I don't know how effective it would be. Perhaps that's just the skeptic in me?

wensing2• 13 years ago

Maybe we could just be happy for the kid and imagine what she could be making at 25?

hamburglar• 13 years ago

I think a lot of people react to the sensationalism of the headlines on stories like this. It's absolutely wonderful that a 15 year old girl is interested in experimenting with little bits of tech like this, and I'm sure she's way ahead of the curve, but the news outlets like to portray this as "15 year old kid invents a new solution to a difficult problem," which is just way overstating it in the annoying style of people who are overly impressed by their own grandchildren's science projects.

Just from the headline, I said to myself, "sounds like some kid discovered peltier junctions and LEDs and the media decided to act like she's invented something," which was exactly right. Good for her, she's learning and experimenting, and that's a great thing, but let's not get carried away with our portrayal of how amazing it is.

Think back a month or so to the girl who "invented" a new way of charging cellphones in 30 seconds using capacitors. The sensationalism of that story was so over the top, I had non-technical people sharing the story with me on Facebook with breathless comments about what a genius this kid was and looking forward to this fantastic tech being available in all of our cell phones. Was it anything like that? No. It was a kid experimenting with well-understood technology and learning how things work, and there was no discovery or invention of anything non-obvious to any actual engineer. I don't want to detract from her industriousness or enthusiasm for learning, but when half the world is convinced she's done something notable enough to get her on the talk show circuit, something is wrong with the reporting.

arbitrage• 13 years ago

Why focus only on the negative, or on a situation for which it would obviously be a terrible choice? It's never going to be as powerful as a battery powered flashlight; that's not really the point.

It might, however, be awfully useful in a stiatuion where there is no ambient light available at all, or where equipment needs to be light and very simply constructed. Perhaps something like in an emergency kit in case of a mine or cave collapse. Or in a situation with very adverse operating conditions, like a desert. Moving parts (as for a hand crank torch) would be a liability in an environment with omnipresent particulate contamination.

aaron6952• 13 years ago

And this is why people get cranky at articles like this, people are not adult enough to take them as what they are, puff pieces to build the esteem of children.

Could a 15 year old child invent safety equipment for the trillion $ mining corps. Of course not.

People with 4 year degrees in engineering have as much commitment and inventiveness as children and money to boot. Plus a fully developed brain.

As is always the case child age x invents new way to do blah, invents object blah they of course haven't.

As a tired cliche does it have a place on HN. Is this site aimed in part at children is the question?

jff2• 13 years ago

You'd better hope ambient temperature is less than 50 degrees.

CognitiveLens• 13 years ago

This flashlight wouldn't be great for lighting up shadows created by strong ambient light, but in complete darkness, even a little light makes a huge difference.

I'm thinking backup light source for camping, spelunking, power outages at home... just enough light to find a path when there is no other light.

chinpokomon2• 13 years ago

What is the hypothesis? As a science fair project, while this is novel as far as most "I made a volcano using baking soda and vinegar" projects are, I'm missing the scientific method in what I've read so far.

NegativeK• 13 years ago

Hypothesis: The Seebeck effect, combined with the heat from a human hand, can generate sufficient power for an LED flashlight at room temperature.

The hypothesis was approached from both the theoretical and experimental side.

bobsy• 13 years ago

As someone with poor circulaton to the extremities I fear I would be walking around in the dark holding the flash light with cold hands.

Its a really nice idea though. Its stories like this that make me wish i paid a bit more attention in science when i was younger.

koudelka• 13 years ago

If your extremities' temperature is cooler than the ambient temperature, maybe all you need is a version with the heat-collection plates flipped?

schiffern7• 13 years ago

If your extremities' temperature is cooler than the ambient temperature, how did you do that? Heat pumps in your arms? ;)

It would be trivial to put some circuitry in there to rectify the voltage so it works in either direction. No separate version required.

(changing ambient temperature is the obvious answer to my joke, btw)

juandopazo• 13 years ago

I guess this is a consequence of the development of the LED. LEDs being so efficient allows for very low power sources and a thermocouple seems to be enough to light them. Pretty cool!

pocketstar5• 13 years ago

Wow, her dad is my coworker and I heard this casually mentioned at work the other day that his daughter was working with Peltiers and I should consult with her because I am also working with Peltiers for characterization of phase change materials.

Also note, calling the device a Peltier is a misnomer, her flashlight is a thermoelectric device utilizing the Seebeck Effect, similar but opposite to the Peltier Effect. Peltier has just become the connotation for thermoelectric devices.

The Seebeck effect only works with a temperature gradient, the flashlight will begin to heat up when held and the Peltier will produce less power. The next step is to add a heat sink and fan to maintain a temperature gradient for operation longer than 20mins.

schiffern7• 13 years ago

Wow, an encouraging comment on HN? Not assuming they're a moron?!?! You give me hope for this place.

Speaking of phase-change materials, why not fill the flashlight with them? It still wouldn't be steady-state of course, but I envision the fan eating up all the power. Heat pipes might help, but they still leave the problem of heat rejection. Evaporative cooling pad?

ChuckMcM2• 13 years ago

Paraffin would be a good choice, although just putting a slug of copper into it and storing it in the freezer would probably work just as well. Of course you have to be able to find your freezer in the dark ...

pocketstar5• 13 years ago

Thanks, No doubt the fan would eat most of the power, thats just another engineering challenge to overcome. There doesnt seem like a better way without making the flashlight huge, then again the scale of power I am used to is an several orders of magnitude greater than what she uses, I probably have a scale bias. Im sure she could design an innovative passive and small heatsink.

Idea: using PCM you could make a flashlight that you recharge in the oven.

solistice2• 13 years ago

I also don't quite think incorporating a fan into the design would increase it's efficiency. A quick google trip for PC Fan power usage gives me 1-2 watts for a 80mm fan. Small 5mm LEDs at 20mA and 3V should, calculated via rule of thumb, be at roughly 60 something mW. It just doesn't quite add up.

Evaporative cooling could work, but if you are planning on even including 20ml of cooling liquid, you could just as well put a CR2032 battery in there, which'll power the thing just fine.

LowKarmaAccount• 13 years ago

When I was in high school I looked into making a micro-power plant using the Seebeck effect for the Intel Science Talent Search. I thought about using liquid sodium as a heat sink, which is what some heliostats use. Solar power towers use the captured energy to power turbines, but this isn't very efficient, so I thought I would add thermoelectric generators to capture some of the energy that is lost as heat.

I ended up not doing this because the Seebeck effect isn't really a useful power-plant (in the broad sense of the word) when you have a small temperature gradient because it is really inefficient, although it is useful for thermometers and other low power items, and for some exotic things like Radioisotope Thermoelectric Generators, which is what powers Voyager and other long distance spacecraft. It becomes worth using when you have a large, consistent energy source, which is usually geothermal energy. But the small temperature difference between the human body and the flashlight and the low efficiency of thermocouples means that this project won't seriously compete with battery powered flashlights. However, it is a cool idea and could have some niche uses.

pocketstar5• 13 years ago

Yup, Seebeck is incredibly inefficient, as for RTG's in space I think they would rather use a Rankine cycle but that would be prohibitively too heavy to launch.

Good on your for using peltiers back in HS. In HS I made a sweet exoskeleton using peltiers for active cooling while outside in the summer heat.

dclowd9901• 13 years ago

Is it accurate to say the device would perform better in cold environments than warm environments, then?

notdrunkatall2• 13 years ago

I believe that would be an accurate statement, yes, and it also would seem that the performance of the device would increase non-linearly.

notdrunkatall2• 13 years ago

A heat sink yes, but a fan? The electrical output is already very low.

theshadow• 13 years ago

Shocked that the top comment is not just another one criticizing or trying to diminish something about the article/story.

temac• 13 years ago

A fan might be counterproductive, drowning too much current.

seabrookmx• 13 years ago

Greetings fellow Victorian.

pocketstar5• 13 years ago

Victoria HN meetup? :D

qwerta2• 13 years ago

Did you read the comments under the article? I usually do not buy sexism in tech, but this got me.

alanchavez2• 13 years ago

I came here to see if anyone else noticed the sexists comments under the article, what a shame.

However it's not difficult to find sexists pricks in tech.

atondwal• 13 years ago

You're probably just the only two who read the comments...

tekromancr6• 13 years ago

However it's not difficult to find sexists pricks in tech.

Or online, or in public.

masklinn2• 13 years ago

Did you read the comments under the article?

It usually isn't a good idea.

I usually do not buy sexism in tech

So I guess you don't "buy" it because you don't usually see it, if only on account of not being on the receiving end of it?

qwerta2• 13 years ago

You have no idea who I am, so please keep your guessing to yourself.

city412• 13 years ago

They must have been removed. The 8 comments that are there are quite benign

lostlogin4• 13 years ago

The fact that gender is mentioned in the headline and discussed there and here points to a different standard for males and females I think. If it was just a passing reference, no problem, but the fact ITS A GIRL is somehow amazing. That's sad.

ISL5• 13 years ago

Very clever!

I'll state for the purposes of prior art that, if you can get enough power to add a little fan or other air-moving mechanism to the circuit to pull air through the tube/heatsink, it will operate in still air for as long as a human can keep it warm.

This opens the mind to a realm of interesting body-powered devices, especially in environments where heat sinking is easy, like for divers, motorcycle riders, and sailors. Want a wetsuit or jacket that lights up or operates sensors on its own? Easy peasy.

solistice2• 13 years ago

Unless you are planning on keeping warm in those environments, which would make strapping heat sinks all over your body a bad idea.

MojoJolo2• 13 years ago

Can this technology work in an airconditioned room? I was thinking if this technology can provide enough electricity to even just lighting up a single room. It can use the heat outside, and the cool air (form air condition) inside the room.

All in all, very good invention! And also inspiring. I hope more teens will be involve in inventing things. I hope she wins. Also, (totally unrelated) I think she's cute. :)

relix2• 13 years ago

Sorry, what you're talking about is a perpetual motion machine, which the laws of thermodynamics forbid. The AC will just have to work harder to get the extra heat added by the thermoelectric device back out, no free energy here.

MojoJolo2• 13 years ago

Thanks. Never had a knowledge about thermodynamics. I just googled perpetual motion and the laws of thermodynamics. And yes, I agree that my comment above doesn't follow those laws. It's good to learn these new things. :-)

ISL5• 13 years ago

It should be provable that thermodynamics guarantees that it will be more power-efficient to generate the light directly with electricity instead of using electricity to cool the room, then exploiting a thermal gradient with even a lossless Peltier element.

tekromancr6• 13 years ago

True, and it is. However, if you are going to be using that energy to cool the room anyway, why not try to reclaim that 'spent' energy?

pocketstar5• 13 years ago

It would 'work' but it would be grossly inefficient. Your room is cooled by a heat pump(air conditioner) a Peltier is just a different heat pump, a very inefficient one at that. You would end up spending much more money cooling the room than it would cost to just power lights normally.

dwyer• 13 years ago

TFA:

due to the temperature reliance of Peltier tiles, the flashlights worked better in colder temperatures (tested at 41 degrees Fahrenheit). The flashlight still worked in warmer temperatures (50 degrees, for instance), but the colder the surrounding temperature, the more the hand’s body heat can help the Peltier generate electricity.

samsquire• 13 years ago

I can't help thinking of a full body suit to harvest the entire heat output of the human body. Maybe you could use assisted sweat evaporation to provide for the cold tile?

It could be like a Fremen suit so they can pump the water coolant around and potentially and power electronics.

mistercow3• 13 years ago

I'm pretty sure the result of that would be that you would overheat as the suit would prevent you from dissipating heat quickly enough.

chockablock2• 13 years ago

I think the risk is that you'd have the opposite problem: hypothermia.

Qantourisc2• 13 years ago

Not to complain, but how much light does it really produce ? Cause this would be very neat ... but I still need to be able to light the room :)

fjarlq• 13 years ago

From her project description[1]:

My objective in my project was to create a flashlight that runs solely on the heat of the human hand. Using four Peltier tiles and the temperature difference between the palm of the hand and ambient air, I designed a flashlight that provides bright light without batteries or moving parts. My design is ergonomic, thermodynamically efficient, and only needs a five degree temperature difference to work and produce up to 5.4 mW at 5 foot candles of brightness.

5 foot candles is about 54 lux. 30 to 50 lux is minimal illuminance for reading.

[1] http://www.googlesciencefair.com/en/projects/ahJzfnNjaWVuY2V...

Qantourisc2• 13 years ago

Thanks

kailuowang• 13 years ago

There is an old Chinese saying: I wish she was my daughter.

dsrguru• 13 years ago

Just out of curiosity, what's the Chinese expression? Is it a 成語?

gdonelli• 13 years ago

She is more eloquent and capable of public speaking that a lot of adults.

More women should see example like these, it is a great example of woman in engineering kicking ass.

phy6• 13 years ago

She should call it the Fleshlight

Kiro• 13 years ago

Google 'fleshlight' and I'm sure you'll agree it would be a pretty bad choice of name.

asdfologist• 13 years ago

whoosh

lostlogin4• 13 years ago

It says that in the comments below the article.

nessus42• 13 years ago

First I have to say that this is very cool indeed!

Practically speaking, however, I'm not sure that it would have any advantages over the flashlights that you crank for a while. Though perhaps those crank flashlights use a rechargeable battery that degrades over time, and this new flashlight would have a longer shelf-life? Though I should think a good capacitor instead of a battery would solve that potential problem with the crank flashlights.

ht_th• 13 years ago

Those crank-powered flashlights make a lot of noise and induce cramps in the hand used to crank it.

iknight• 13 years ago

It seems to work well for me. My son loves his. Granted I don't use it as a necessity.

maxerickson• 13 years ago

Junk like this:

http://dx.com/c/flashlights-lasers-999/led-flashlights-901/a...

will make quite a lot of light using a single NIMH AA that has been out of a charger for weeks (pushing ~ 1 volt...). It doesn't get you to 0 batteries, but it does a nice job of making light when you happen to realize you need it (without thinking about it in the interim).

fps• 13 years ago

I've never had one of those crank flashlights work after more than a few hours of use. I bought several for my kids, and they didn't even make it through a weekend camping trip. I also tried keeping one in my car, and found that the second or third time I tried to use it, it would light up dimly for a few seconds after several minutes of cranking. Some component, either the capacitor or the generator, has a very high failure rate.

skriticos2• 13 years ago

So if she is using the power of the human body to power a flashlight when she is 15, does that mean she'll design the technical foundation of the Matrix when she is 30? (which had the purpose to harvest the human energy)

Sorry, could not resist. Great to see our youth being creative.

twodayslate• 13 years ago

Put this in phones to charge them when you aren't using it?

jff2• 13 years ago

Won't work very long, it operates using the temperature differential between your hand and the interior of the flashlight. Which, based on the quoted "still worked at 50 degrees F", means you'd have to stick your phone in the fridge when you're not using it. And then take it out so it can charge just a little bit before the temperature equalizes.

bentcorner• 13 years ago

Alternative, could you use this to capture waste heat from the phone internals?

Anonymous238• 13 years ago

Invented is a strong word when these already exist.

http://www.youtube.com/watch?v=pFqrx2-ENgE

theoj• 13 years ago

Interesting. More info here:

http://thermalforce.de/de/product/module/index.php

http://thermalforce.de/de/download/m101.pdf

ThermalForce says price is available upon request -- so it may be available for sale as a custom order. There are some other interesting products at that first link as well.

sliverstorm• 13 years ago

You don't have to be the first one to invent something, to invent it.

It doesn't suddenly become imitation if you came up with it on your own.

zerr• 13 years ago

Of course, but with nowadays available information and possibilities to search, it is quite easy to find that it is already done. I mean, I don't think she invented it being sitting in some cave, without contact to outside world. She would at least need to have done some simple research, with the materials and etc... So some organic results would pop up.

kirchhoff• 13 years ago

Reminded me of the Seiko Thermic, a wristwatch powered on the same principle.

rikkipitt• 13 years ago

Blean (n.)

Scientific measure of luminosity : 1 glimmer = 100,000 bleans. Usherettes' torches are designed to produce between 2.5 and 4 bleans, enabling them to assist you in falling downstairs, treading on people or putting your hand into a Neapolitan tub when reaching for change.

~ Douglas Adams and John Lloyd

Ellipsis753• 13 years ago

My favourite part of the article was: "The flashlight maintained a sufficient level of light for over 20 minutes, definitely enough time to find the candles in the dark when the power goes out."

Why not just put the candles where the flashlight was in the first place? (or just put a reliable battery powered flashlight there.)

It sounds like it's saying "this flashlight should last long enough for you to find your better flashlight".

hcarvalhoalves• 13 years ago

Way to go. Good to see a girl that age interested in science and engineering.

circuiter• 13 years ago

For anyone interested, here's the list of all the finalists this year - most of them much more impressive.

http://www.businessinsider.com/2013-google-science-fair-fina...

stormbrew• 13 years ago

She should be using blue LEDs. I swear those things can send light through a wall.

vidarh2• 13 years ago

I bought a pack of 400 little round black stickers only for the purpose of covering blue leds... For most of the devices I have with blue leds it takes 2-3 stickers on top of each others to dim them enough for me to still see them but not feel blinded when the light in the room is dimmed..

alexhawdon• 13 years ago

They certainly are bright, but the light is a terrible colour for us humans. An Optician friend explained to me that the shorter wavelength of blue light causes it to focus in front of the retina, which is why blue LEDs appear out of focus when you look at them.

15-year-old girl invents flashlight powered by the heat of your hand

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