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Solar Cells Integrated In Microchips

timothy posted more than 3 years ago | from the new-breed-of-calculator-watches dept.

Power 38

cylonlover writes "In a new, more efficient approach to solar powered microelectronics, researchers have produced a microchip which directly integrates photovoltaic cells. While harnessing sunlight to power microelectronics isn't new, conventional set-ups use a separate solar cell and battery. What sets this device apart is that high-efficiency solar cells are placed straight onto the electronics, producing self-sufficient, low-power devices which are highly suitable for industrial serial production and can even operate indoors."

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So cheapo calculator... (0)

Anonymous Coward | more than 3 years ago | (#34720430)

...now $0.50? maybe go roll-to-roll?

Packaging for ESD protection? (0)

Anonymous Coward | more than 3 years ago | (#34720436)

So "high-efficiency solar cells are placed straight onto the electronics" and of course it has to "see" light (even indoors)--then how is this gonna be packaged for protection from high electrostatic discharges?

Re:Packaging for ESD protection? (4, Informative)

Rosco P. Coltrane (209368) | more than 3 years ago | (#34720452)

The same way EPROMs were: a standard opaque package with a quartz window.

Re:Packaging for ESD protection? (3, Funny)

MichaelSmith (789609) | more than 3 years ago | (#34720492)

Good way to frighten old timers: run you chips in a UV eraser.

Re:Packaging for ESD protection? (1)

mpe (36238) | more than 3 years ago | (#34720730)

Good way to frighten old timers: run you chips in a UV eraser.

The article does not mention the frequencies of light which the device uses to generate electricity.

Re:Packaging for ESD protection? (1)

MichaelSmith (789609) | more than 3 years ago | (#34720792)

Good way to frighten old timers: run you chips in a UV eraser.

The article does not mention the frequencies of light which the device uses to generate electricity.

True but I did wonder if it could be used as a radiation detector in various contexts. Maybe a little chip on a bracelet which sounds a warning when your UV exposure has gone beyond a limit.

Re:Packaging for ESD protection? (0)

Anonymous Coward | more than 3 years ago | (#34733548)

ha ha, very funny there, sonny boy. Keep saving up and maybe I'll beat you with my cane made from a special experimental alloy.

Re:Packaging for ESD protection? (1)

PatPending (953482) | more than 3 years ago | (#34723452)

As I recall, having a quartz window will necessitate a ceramic package instead of plastic, so the manufacturing cost and also the mass of the device just considerably increased.

Re:Packaging for ESD protection? (1)

ls671 (1122017) | more than 3 years ago | (#34720562)

Don't worry, France will come up with a nuclear powered version so light won't be needed anymore...

Re:Packaging for ESD protection? (1)

Anonymous Coward | more than 3 years ago | (#34723280)

Don't worry, France will come up with a nuclear powered version so light won't be needed anymore...

Who needs nuclear when you can power the country with burning cars?

Re:Packaging for ESD protection? (1)

grommit (97148) | more than 3 years ago | (#34730376)

Easy, you position a LED above the solar cell inside the package and then power the LED with an external solar array.

Chip below 1 MilliWatt power (1)

the100rabh (947158) | more than 3 years ago | (#34720458)

Chip below 1 MilliWatt power, hmm so Intel and AMD are ruled out


---
In the brave new world, learn to want more

Bypass Gizmag, direct URL (4, Informative)

PatPending (953482) | more than 3 years ago | (#34720470)

Re:Bypass Gizmag, direct URL (-1)

Anonymous Coward | more than 3 years ago | (#34720512)

You're all trolling in a nigga thread.

Re:Bypass Gizmag, direct URL (1)

davester666 (731373) | more than 3 years ago | (#34723142)

Except it's packaged inside a protective case which is typically opaque. So you'll need to connect a little LED to the chip to provide the light.

What use? (1)

jklovanc (1603149) | more than 3 years ago | (#34720486)

Considering the power drain must be "well below 1 milliwatt", what could such a chip be used for?

Since the solar cell piggybacks on the chip, wouldn't the chip be exposed to the elements in order to generate electricity?

All the article states is that it could be manufactured not what it could be used for..

Re:What use? (0)

Anonymous Coward | more than 3 years ago | (#34720558)

High tech opto-isolator?

Re:What use? (1)

Anonymous Coward | more than 3 years ago | (#34720570)

As a CS student about to graduate and applying for grad schools, I hope I can answer this one pretty easily:

put the entire chip beneath a glass/etc protector of some kind, since photovoltaic uses photons(which pass through glass/etc) shouldn't be much issue , IANA(chemist/physicist)... so I think this is right

and for the use... that one I'm more sure on, many possible ideas pop to my mind, environmental sensors of some kind... temp, chemical, moisture, etc.... have this chip as the collection and storage (ram) processor, and then a RFID chip/antenna is used for collection (providing the electricity needed for that chip by the radio waves). RFID/cpu/ram/solar could all be built into one chip at some point, then that would reduce costs/etc

That is just one obvious example, which allows two chips that collect their own energy to used together...(or built into one chip....) to provide a service which wouldn't need any additional energy input (other than light/RF) , this could be a long-term cost-effective way to do lots of things like inventory, intrusion detection... at banks(safety deposit boxes)/server farms, or ...._many_other ways...

Single-chip response (1)

tygerstripes (832644) | more than 3 years ago | (#34720840)

Hmm... provided you could build some capacitance into the die, it would be trivial to manufacture, en-masse, an array of incredibly inexpensive devices that could respond to a light-signal stimulus, much the same way that RFID tags respond to a suitable RF signal.

I can't think of an immediate application, but the key technical difference would be that you can transmit focussed, directional light in a laser, which is a much more difficult and wasteful feat with RF. You could therefore elicit a response from one of these chips at pinpoint accuracy and great range, which is not currently possible with RFID. I'm sure some more innovative people than I could conceive of a novel application.

Re:Single-chip response (1)

noidentity (188756) | more than 3 years ago | (#34723042)

Hmm... provided you could build some capacitance into the die,

Capacitance definitely makes it more interesting, because the device can store energy for a period, and then use it in a short burst. The instantaneous current can be greater than supplied by the cell, so it could transmit things etc.

Re:What use? (5, Interesting)

noidentity (188756) | more than 3 years ago | (#34720590)

The exposure was my first thought as well, but from an electrical standpoint. A solar cell is just a diode with a large junction area, as I understand it, and most semiconductors are light-sensitive, so it didn't seem you'd want them exposed to intense light that causes currents to be generated throughout the circuit. But here they put the traditional circuitry on a layer below the solar cell. Still, as you note, the solar panel is so small that it generates very little power. If you increased its area, you'd increase the area of the underlying layer as well, which seems it'd increase its cost. Sure, it wouldn't have circuitry in the entire area, so the defect rate wouldn't scale as badly as it does for normal large chips, but it still seems it'd be cheaper to just use a separate solar panel of whatever size is needed. Maybe this would have a really specialized use.

Re:What use? (1)

ortholattice (175065) | more than 3 years ago | (#34721514)

most semiconductors are light-sensitive

Indeed, many years ago I built an experimental bidirectional fiber-optic link simply by gluing LEDs to each end of a short (3m) plastic optical fiber. (I ground down each LED close to its chip, then polished it and glued it with clear epoxy.) When not powered, the LED would act as a photodiode. It wasn't very fast - the slow response of the circuit I used to amplify the weak current limited it to perhaps 100KHz. But it worked.

Re:What use? (1)

panopea (937339) | more than 3 years ago | (#34723424)

There is a small revolution in progress for "energy harvesting" technology. Where micro watt level power generation is just fine. This is an obvious next step that will reduce chip count. Already waiting for data sheets.

Re:What use? (2)

Ernesto Alvarez (750678) | more than 3 years ago | (#34720656)

Light sensor with built in amplifier.

Re:What use? (1)

jklovanc (1603149) | more than 3 years ago | (#34720708)

With an output of less than 1mW; not much of an amplifier. Wouldn't that be a light sensor powering a light sensor? Why not just use the solar cells as the light sensor?

Re:What use? (1)

Ernesto Alvarez (750678) | more than 3 years ago | (#34720856)

That's what I meant.

If you used a solar cell as a light sensor, it'll deliver just a few milliwatts that you'd have to amplify anyway.
With this technology, you could place one of these cells on top of an amplifier, and apply power to the whole thing. It would then give you a reading of ambient light in a more reasonable range (say from 0V to V+), straight from the chip.

This could be useful as a one chip light sensor, say for a digital camera.

It would simplify light sensing equipment a lot, leading to very low prices.

Re:What use? (1)

jklovanc (1603149) | more than 3 years ago | (#34724554)

You have succeeded in describing all light sensors in use today; a solar call with an externally powered amplifier.

Re:What use? (1)

jonbryce (703250) | more than 3 years ago | (#34720786)

Like a photodiode, which has been around for ages?

lightsensor (0)

Anonymous Coward | more than 3 years ago | (#34720882)

Using the solar cell for light-sensing is okay, it is the same as using a photodiode. But with some extra circuit, and band-gap reference you can make the sensor more accurate. and if you are very good, you might be able to store the measurement in a flash memory. (of course you can drive other type of sensors. Like ChemFET base sensors, but that's another story)

The field where this can be applied is rather narrow. -> suboptimal solar-cell + suboptimal integrated circuits.
These low power chips (few mW) are usually very small, and area really matters in chip price. So I see a solar cell which has a small chip manufactured right into it.
But I still don't think it is a very marketable idea.

Re:What use? (1)

Ernesto Alvarez (750678) | more than 3 years ago | (#34720932)

I guess so.

There probably is some advantage of using an amplifier in that role, but I'm just to green to know.

Re:What use? (1)

drinkypoo (153816) | more than 3 years ago | (#34720926)

It could be good for a pre-amp on a sensor signal which absolutely must be as isolated as possible... eliminating noise on the power line.

Yeah, I'm reaching. A more likely actual use is an outdoor active RFID tag.

Re:What use? (1)

noidentity (188756) | more than 3 years ago | (#34723004)

It could be good for a pre-amp on a sensor signal which absolutely must be as isolated as possible... eliminating noise on the power line.

If the light it was powered by had any brightness modulation, it would pick that up as power supply noise as well, so you need a filter on the power supply regardless. Common examples of modulated light are LED and fluorescent, which are quite common.

What economic use? (3, Insightful)

dtmos (447842) | more than 3 years ago | (#34720996)

what could such a chip be used for?

The important question to ask is, "what could such a chip be economically used for?"

Unless one is developing something for military or other national security-type purposes, where cost is typically significantly less important than attaining the ultimate in performance (however "performance" is defined in the application), the question typically is, "what's the cheapest way to do X?"

If, as is frequently the case, X is defined as "power the chip," one has an interesting economic quandary: In terms of money/area, conventional solar cells, especially amorphous solar cells, are about the cheapest form of silicon known to man. Using this new technology, though, these solar cells would be replaced by area on an integrated circuit, which is about the most expensive form of silicon known to man. Worse, the power consumed by the electronics must be minimized ("below 1 milliwatt"), so one is pressured into using very fine-lithography silicon, which is the most expensive form of silicon known to man.

The only way I can see that one wins on cost with this technology is if one has electronics that are so low-powered that they can be powered by an amorphous solar cell with an area equal to that of the circuitry itself. If you need a point of reference on the practicality of this requirement, I point you to your average solar-powered calculator, which has a solar cell area of several cm^2, and an active circuit area of probably less than 5 mm^2.

If, however, X is defined as "power the chip with a monolithic structure," perhaps for acceleration, board area, or other system-level requirements, then using external solar cells is prohibited (by the terms of the game), and then this technology begins to look more appealing. Even then, however, I would wonder if it wouldn't be easier to use chip stacking [siliconfareast.com] or similar technology to put a solar cell on a chip, since then each die could be processed in a manner optimum for its purpose (solar cell or integrated circuit). And, of course, you're still left with the problem of getting sufficient power from such a small area.

Re:What economic use? (1)

dbIII (701233) | more than 3 years ago | (#34727408)

As an earlier poster pointed out, much larger defects can be tolerated on the photovoltaic portion ("they put the traditional circuitry on a layer below the solar cell") so the costs would not be expected to be as astronomical as if the electronics were side by side with the photovoltaic portion with a very small allowable defect size. If it was side by side you'd expect the sort of costs that prevent us all from having 35mm digital backs on our cameras (whopping big bit of very expensive silicon vs a much cheaper small sensor in digital cameras).

Re:What economic use? (1)

Squirmy McPhee (856939) | more than 3 years ago | (#34730522)

The only way I can see that one wins on cost with this technology is if one has electronics that are so low-powered that they can be powered by an amorphous solar cell with an area equal to that of the circuitry itself. If you need a point of reference on the practicality of this requirement, I point you to your average solar-powered calculator, which has a solar cell area of several cm^2, and an active circuit area of probably less than 5 mm^2.

According to the press release from University of Twente [utwente.nl] , they will use amorphous silicon or CIGS layers deposited on top of the integrated circuit. A pretty average amorphous silicon solar cell will produce 6 mW/cm^2 in full sunlight, and about 0.5 mW/cm^2 indoors. A CIGS cell, especially on such a small scale, could probably come close to tripling those figures (one of the biggest problems in realizing high CIGS cell efficiencies in mass production is getting layers of uniform quality over large areas, an issue that would be dodged in this case).

The press release from Twente says the power requirement is "well below 1 mW"; if you assume the actual requirement is 0.1 mW and you use CIGS cells then you could probably still get enough power to run the circuit indoors on 6-7 mm^2 area. That doesn't seem out of line to me, but then I'm a solar cell designer, not an IC designer....

Re:What use? (1)

camperdave (969942) | more than 3 years ago | (#34723468)

Ever hear of acrylic, or polycarbonate, or nalgene? Just because it needs to be exposed to the light, doesn't mean it can't be encased in plastic.

It was we who seared the sky (1)

nounderscores (246517) | more than 3 years ago | (#34723226)

The machines were using the sun for energy!

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