Saudi Arabia is developing a new RFID chip to be embedded into its currency
Steven Cherry: Hi, this is Steven Cherry for IEEE Spectrum’s “Techwise Conversations.”
Have you heard about the tracking device in U.S. banknotes? There’s a plastic strip embedded in $20 bills that lets the government track them and count how much money is in your wallet by sending a signal to a satellite.
That’s an urban legend that dates back to at least 2001, but something a bit like it is coming true in Saudi Arabia.
Researchers at the Functional Nanomaterials and Devices Laboratory at the King Abdullah University of Science and Technology are working on putting a memory device into banknotes.
As in the U.S. $20 bills, the purpose is to cut down on counterfeiting,
but unlike them, the Saudi system has some electronics on board. It can
send an RFID radio signal to a scanner, and it contains some
nonvolatile memory that can store a record of it every time it’s
scanned.
The research is described in a new article in the Wiley journal Advanced Materials. The article is titled “High-Performance Non-Volatile Organic Ferroelectric Memory on Banknotes,” and its authors are M.A. Khan, Unnat Bhansali, and Husam Alshareef,
who is my guest today. He’s an associate professor at King Abdullah
University of Science and Technology. His area of expertise is materials
science, the field in which he earned a Ph.D. from North Carolina State
University in 1995.
Husam, welcome to the podcast.
Husam Alshareef: Thank you very much, Steven
Steven Cherry: Husam, this is essentially a chip
that’s small enough to be embedded in a banknote, and it can survive all
the wear and tear that paper currency is subjected to. Your group is
working on one part of it—the chip. But I gather the trickiest thing was
getting the materials right.
Husam Alshareef: Correct. So, this project actually is
quite ambitious because, as you mentioned, the banknote gets a lot of
bending, a lot of folding, and it is necessary to get the right
materials to actually be able to handle all kinds of bending and
flexibility in these banknotes, as you know. So, usually the RFID tag
has three components: It has, actually, the antenna; and it has—if you
will, just to simplify things—transistors; and it has a memory part of
it, a logic and memory part to it. So in the first part of this work, we
actually worked on the logic and the memory. The antenna part has not
been implemented yet, but we are currently working on that. So these
materials, to be maximally flexible, actually, were all organic. So,
what we set out to do is an all-organic...including the contacts,
including the transistors, the capacitors, all these circuit components
had to be organic to withstand the significant amount of flexibility
that is needed for handling a banknote.
Steven Cherry: I guess heat would have been an issue with silicon as well.
Husam Alshareef: Yes. So to be able to do it in
silicon, you would have to heat, as you know, to very significant
temperatures—you know, hundreds of degrees Celsius. But in the case of
these materials, they can actually be processed at very low
temperatures—like 140 C or below, the banknote, we have shown, can
handle.
Steven Cherry: And in the U.S., banknotes are even
designed so they can survive being laundered—you know, put in a washing
machine or something.
Husam Alshareef: And ironed as well, actually. The
students, before they actually started building the devices, what they
did, we went through a rigorous exercise of dipping the banknote in
different solvents, ironed it directly with an iron, actually, heating
it to different degrees, and actually they are more tenacious than I
thought.
Steven Cherry: Very good. Now, the chip draws power
from the scanner when it’s scanned. I guess that’s not uncommon, but it
means the power requirement has to be very slight.
Husam Alshareef: Exactly. And this is basically why we
set out to implement the ferroelectric memory, because the
ferroelectric memory is nonvolatile. That means it does not need to
continually be refreshed, as in DRAMs, for example. DRAMs, they need to
be continually refreshed with an onboard source of power, otherwise you
lose your information. The ferroelectric memory is unique, in that
sense; it does not need any refresh, so you don’t need power. So
whenever the power comes from a signal, that can be used to read or
write the memory.
Steven Cherry: The Saudi riyal is a very pretty, colorful currency. Does this change the appearance at all?
Husam Alshareef: It can. This is one thing that one
has to optimize. If you look at in our publication, actually, because in
this case we did use the top layer as gold contact, and the thickness
of the layers may have not been optimized. Intrinsically, the layers we
used other than gold are transparent, so in principle, when all the
thicknesses are optimized and the roughness of the layers, you should
not be able to see this by eye.
Steven Cherry: It takes money to make money, and you just mentioned gold. I gather you would like the final system to not use gold at all?
Husam Alshareef: Yeah. Actually, we are already at a
stage where we do not need to use gold. But if you look in the paper, we
have devices that use both to try to make the comparison. Gold will
ultimately not be used in those. And also, we are thinking these things
could probably be for the higher-value currencies, you know, instead of,
like, small denominations.
Steven Cherry: Now, exactly how will this system cut down on counterfeiting?
Husam Alshareef: So, there have been many ways to try
and combat counterfeiting. A lot of them, like the holograms, like the
raised features on the banknote and maybe embedded threads of metal, you
know, all these things—we’re all familiar with those. We thought with
electronic counterfeiting, actually, it may be more difficult to
reproduce. For example, you could make raised text, but if you have a
unique number that is actually encrypted for each banknote, then it
would be very difficult to reproduce that, we thought.
Steven Cherry: That could be done without the nonvolatile memory, right?
Husam Alshareef: You could. Right now, the RFID tags
are using what’s called EEPROMs. It’s a different kind of memory, but
its disadvantage is that it has limited endurance, which means the
number of times you can scan will be limited, but it also consists of
complex circuits. You will need multiple transistors to implement a bit
of memory. The beauty of these ferroelectric memories is that you can
have a single transistor actually for the memory, which is a much
simpler circuit. Also the EEPROMs that are currently used are slower—not
that you need extremely high speed for this application, but still, the
ferroelectric memory would give you an advantage in terms of speed.
Steven Cherry: Once there are enough bills and
scanners out there, and bills routinely have this embedded in it and are
scanned at every transaction—which is in principle possible—there’s the
potential for quite a database for how money changes hands. Would this
let a government go after drug traffickers, for example?
Husam Alshareef: Absolutely, especially in large
denominations. I think the circuit can become as complex as you want it
to be, right? I mean, in its simplest form, the circuit is not very
expensive, and it can be quite simple to implement, actually, but if you
want inventory and tracking and positioning like this, you could
basically add functionality to the circuit. And this could also again be
done with organic materials and go beyond knowing [whether] this is
just a bona fide, government-issued banknote or not. You could go into
tracking and locating banknotes and so forth; it’s just you design the
circuit you want to appear on the banknote.
Steven Cherry: And so it could also help a government
go after the so-called “gray economy,” like waiters and cab drivers and
everybody else who works mainly in cash and might be underreporting
their income.
Husam Alshareef: It could, but that was not our intention. [laughs]
Steven Cherry: I mean, it could be used by a
government for any reason, right? I mean, if a government wants to track
who’s purchasing alcohol or something.
Husam Alshareef: Yeah, I think actually you’re
bringing up some ideas we didn’t entirely think about, all of those. You
know, counterfeiting is definitely one of the leading, but these are
all interesting applications. And in principle, I would say RFID tags
have many reasons and many areas of uses for RFID tags, and this could
basically whatever one wants to do with banknotes with this robust
circuit that requires low power and flexes very nicely and can be
produced cost-effectively. You can address many of these things that
you’re talking about because the cost will be reasonable.
Steven Cherry: Yeah, it occurs to me that the same
advantages that it presents here would also make it the RFID chip of
choice to embed into clothing and all sorts of other places.
Husam Alshareef: Yes, that is definitely ongoing, many
people are interested in that, including government. Actually, I got
invited to give a talk in Dubai about this. There’s a conference that
happens there about IDs and security and printing on banknotes and
things like that, so there’s interest in that.
Steven Cherry: Well, thank you very much. It’s a really interesting piece of research, and I wish you luck with it.
Husam Alshareef: Thank you very much, Steven. Have a great day.
Steven Cherry: We’ve been speaking with materials
scientist Husam Alshareef about work being done in Saudi Arabia to
create an embedded RFID chip for paper currency.
For IEEE Spectrum’s “Techwise Conversations,” I’m Steven Cherry.
Announcer: “Techwise Conversations” is sponsored by National Instruments.
