cnidocyte
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What solvent should I use to dissolve this bus pass?
I buy these 5 day bus passes that are made of cardboard but operate on smart card technology. I've heard of people dissolving their plastic smart
cards in acetone and attaching the circuitry to their watches as an alternative to carrying a plastic card around. I wanna try this myself to satisfy
my curiosity. These bus tickets cost 15 euros though so I don't want to risk destroying the circuitry.
What would be a good solvent to dissolve the cardboard but leave the circuitry intact? Cardboard consists mainly of cellulose if I'm not mistaken so
I'm guessing a polar solvent is what I need. In my case its either water or methanol/ethanol.
[Edited on 3-12-2010 by cnidocyte]
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entropy51
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Sounds like a bad idea to me, but cellulose is soluble in Schweizer's Reagent.
I suspect anything that dissolves the card will not improve the "circuitry".
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not_important
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Cellulose is a high polymer and doesn't readily dissolve in solvent that you'd want to expose circuitry to. There are a cellulose-attacking enzymes
that will convert the cellulose to shorter chains - starches and sugars. Solutions of Cu(OH)2 in strong aqueous ammonia ( http://en.wikipedia.org/wiki/Schweizer%27s_reagent ) will also dissolve cellulose, but very well could damage the electronics; carbon disulfide
plus aqueous NaOH will also dissolve cellulose; in general such solutions are rather viscous and repeated washings with fresh solvent may be needed to
clean the chip.
Why not just figure out what the chip is and and cut it out, note that there may be an antenna in the card as well. Or just tape the card to your
mobile phone, who uses watches anymore these days?
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cnidocyte
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I know exactly where the chip + antenna is, I can even feel it. I got a swiss army watch as a christmas present so I use it, although I agree they're
pretty useless these days. Attaching bus pass circuitry to it will make it a bit more useful. Yeah I'm gonna just cut it.
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DDTea
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I'm going to sidetrack this a bit... I wear a watch. I love watches. There's something wonderful about a well-constructed analog watch. Clockwork
has always fascinated me. You and your cellphones, just like you and people with digital watches all those decades ago! Always trying to say the
watch will go extinct. Just like when Moses came down from the mountains to find the Hebrews had constructed a false idol and ignored the timeless
God! Your mobile phones will perish and the timeless elegance of analog watches will live on.
Anyhow, yes--cutting it out sounds like the best bet. When I need to digest organic material, I either a) add nitric acid to first oxidize it prior
to adding HCl, HF, and HClO4...or b) throw it into a muffle furnace to burn it off. Neither of those options sounds good for preserving circuitry.
"In the end the proud scientist or philosopher who cannot be bothered to make his thought accessible has no choice but to retire to the heights in
which dwell the Great Misunderstood and the Great Ignored, there to rail in Olympic superiority at the folly of mankind." - Reginald Kapp.
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not_important
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I never coulld wear a watch for long. I'd look down and the crystal would be missing, on a 'rugged' watch. Or the plating would be etched off, or i
would just have stopped working. I don't have either a watch or cell phone, clock in my head does well enough for the time generally. But I laugh
when someone with a mobile in their hand asks me the time...
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cnidocyte
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Have to agree with you there DDTea. Since I started wearing a watch I've grown pretty attached to it. A mobile phone you have to pull out of your
pocket and a watch is already on your arm.
Anyhow I just split the ticket into 2 layers and this revealed the circuitry.
That can only be seen when I shine the light through it, theres still a thin layer of paper covering the conductors but I'm reluctant to scratch it
off cuz these conductors are paper thin and look pretty fragile.
EDIT: I went all out and exposed as much of this circuitry as I could
its all embedded in a thin sheet of plastic. Can't wait to see if this thing still works. All the metal strips are intact. Its hard to imagine how
there are actually components in this thing. Highly impressive. Times like this I regret taking chemistry instead of electronics engineering cuz its
insane how fast electronic technology is evolving.
[Edited on 3-12-2010 by cnidocyte]
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DDTea
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| Quote: | its all embedded in a thin sheet of plastic. Can't wait to see if this thing still works. All the metal strips are intact. Its hard to imagine how
there are actually components in this thing. Highly impressive. Times like this I regret taking chemistry instead of electronics engineering cuz its
insane how fast electronic technology is evolving.
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...and rest assured, the lifetime of relevance for an electrical engineer is also very short for this very reason. 5 years after graduating and all
their knowledge is already outdated.
EDIT: Wait, so is there a thin piece of plastic with the embedded circuitry between layers of cardboard?? Is that the portion that people
have dissolved with acetone to embed onto watches?
[Edited on 12-4-10 by DDTea]
"In the end the proud scientist or philosopher who cannot be bothered to make his thought accessible has no choice but to retire to the heights in
which dwell the Great Misunderstood and the Great Ignored, there to rail in Olympic superiority at the folly of mankind." - Reginald Kapp.
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cnidocyte
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Quote: Originally posted by DDTea  |
EDIT: Wait, so is there a thin piece of plastic with the embedded circuitry between layers of cardboard?? Is that the portion that people
have dissolved with acetone to embed onto watches?
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Yeah that plastic sheets sandwiched between the front and the back of the bus pass. This definitely isn't the same type of circuitry that they put in
plastic smart cards. This thing is just a passive RFID tag by the looks of it. Looks just like this one
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