Jan 08, 2014

Paper Harvester?

posted by Bryon Moyer

My skeptic senses are tingling a bit here… Perhaps unfairly; let’s see.

Energy harvesting is a big deal these days, with folks off trying to scavenge enough power to do useful things without the need for an external connection or a battery. Is it possible to take an old party trick and rebrand it as energy harvesting?

Disney has been getting a fair bit of attention over their “paper energy harvester.” Here’s the deal: paper and Teflon are rubbed together, creating a field via the triboelectric effect. The Teflon takes electrons from the paper, setting up an electret. It’s high voltage, low power: around 1000 V open circuit, 40-50 mW through 1 MΩ.

Let’s switch around the language and materials a bit and see if looks at all familiar. Tribozeau the Clown comes to a kids’ birthday party with balloons aplenty. He dazzles them by taking a balloon and rubbing it on his baggy pants. He holds it near a child’s hair; the hair sticks out, yearning for contact with the balloon. He then sticks the balloon to the wall, where it dutifully remains in defiance of gravity. He explains this (as if anyone is listening) as “static electricity.”

Once I watched the demos of the paper harvester, I couldn’t help feeling like all we’re seeing there is good old-fashioned static electricity (which is what the hoi polloi would call it; “triboelectricity” seems so much more elegant).

Depending on the mechanical configuration, you can tap, rotate, rub, or slide the surface with your fingers to generate the effect. The difference from the party trick appears to be that they’ve harnessed it to do something: activate e-paper, blink some lights, whatever might be possible with the given power budget.

It’s a real-time thing only; no energy is being stored. Use it or lose it. My sense is that it’s interesting for interactive displays; Discovery Museum kind of stuff. I can’t decide if it’s more than a gimmick. Granted, for an entertainment company like Disney, there could be something here. But beyond that?

Perhaps it could serve as an actuator – you know, for, say, a light switch. Just enough to kick on the mains juice. But does it have benefits over alternative approaches? Part of what’s touted is its simplicity – you could build it at home. But again, that’s Science Fair stuff – does it matter commercially?

What do you think? Am I missing something here? Is this more than I’m seeing? And are there significant use opportunities that are whooshing madly over my head?

Click here to see their original paper (as PDF).

Tags :    0 comments  
Jan 07, 2014

Your Wall As a Touchscreen

posted by Bryon Moyer

Pico-projectors sound like an absolute dream for anyone who has to travel with a standard projector in tow. Being able to attach a small device to your phone has the potential to eliminate one heavy bag and to give your shoulder a badly-needed rest. In reality, of course, they don’t have the power that a “real” projector has, so you’re not going to thrill an audience in a big room using your phone. But when the need arises, they can allow for ad hoc display of anything on a modest patch of wall.

Microvision is in this business; they make a pico-projector that uses a single laser for each color and a movable mirror to create a workable image for a small presentation or a heads-up display.

Much of their future work will focus on the same thing everyone else is focusing on: reducing power. Right now they do that by blanking any lasers that aren’t in use at a given instant; future gains will be had by improved green and blue LED efficiency, working an efficient modulation scheme, and taking advantage of Moore’s Law improvements in the digital controller. All to get under 1 W. I know; sounds high, but this thing is all about projecting enough light to overcome the ambient. Ever wonder how much power those monster projectors in auditoriums suck down? Lots, judging by the cooling units… And that’s for use in a darkened room…

But power reduction is an evolutionary improvement. This year they’re looking to change the game by measuring reflections when the scanning laser beam is blocked by something like a finger. Since the system knows where it was shooting the beam when the unusual reflection occurred, it can provide coordinates for the obstruction. In other words, if you point, the system can figure out what you’re pointing to.

This really changes the nature of the presentation from simply a passive transmission of visual images to a – must I use the phrase? – collaborative engagement. The idea is to turn the wall where this is being projected into a temporary tablet on the scale of 2-3’ (5-8’ in a darkened room).

I’m assuming that this isn’t trivial to do. The background against which these “reflective anomalies” (I made the phrase up for lack of a better one) are detected isn’t predictable. One day the projector might be in a bright room shining on a yellow wall; another day, another café, perhaps darker, with a light blue wall. So they will presumably need to normalize the current environment as a calibration step so that they can figure out when a reflection is anomalous.

 But this seems typical of a lot of the work being done in the realm of smart systems: extract useful signals out of extraordinarily noisy environments. We actually seem to be getting pretty good at it.

This capability isn’t available yet, but they said to watch for it in 2014. And watch we will.

Tags :    1 comment  
Dec 19, 2013

Mysterious IR Array

posted by Bryon Moyer

Our bodies have evolved on practical, not principled, grounds. So we have one sensor for photons in the visible spectrum, and we have a completely different sense for photons at wavelengths just longer those in the visible range. One we perceive as light; the other as heat.

But in fact, we now know, intellectually, that they’re just different frequencies of the same thing. It just doesn’t feel that way.

Well, Bosch has taken a page out of the physiology book with its recent infrared detector array. Instead of detecting photons, it also detects heat. They use a porous silicon membrane plus diodes to generate an image that’s admittedly not high-res. And not intended to be.

This isn’t about badass pinpoint-perfect night vision; it’s about low-cost industrial or other applications where resolution per se isn’t the goal. Perhaps you’re trying to distinguish human from animal. Or monitoring train bearings to make sure they’re not overheating.

In fact, this sensor didn’t originate in the consumer Sensortec division; it’s marketed out of the automotive division, which makes me wonder whether they had (or have) a specific auto application in mind. Or perhaps “locomotive” is close enough to “automotive”… (or does that sound crazy?)

I’d send you to a release for more information, but… they didn’t issue one for this. I’d send you to a web page… but I can’t find one (I haven’t found a way to get to these kinds of products on Bosch’s website… it’s all about higher-level modules and systems… even Googling doesn’t help). It was just a conversation I had at the MEMS Executive Congress. I’d say, “You saw it here first,” except perhaps, “You saw it here only” is more appropriate. And has me wondering, “Did I really have that conversation??”

So perhaps your friendly neighborhood Bosch Automotive salesperson would be the next step if you want more info…

Tags :    1 comment  
Get this feed  

Login Required

In order to view this resource, you must log in to our site. Please sign in now.

If you don't already have an acount with us, registering is free and quick. Register now.

Sign In    Register