Stretching the circuit like a piece of chewing gum doesn't break the light bulb's electrical connection.
Tokao Someya
8:02 AM imtracynotstacy: Good morning/good evening
takao.someya: Good morning.
imtracynotstacy: are you ready?
takao.someya: Yes. imtracynotstacy: great.....so let me first ask you, where are you writing from?
takao.someya: I am writing this from Tokyo.
8:06 AM imtracynotstacy:
so...as I mentioned earlier, I'm interested in hearing more about your
team's work with the stretchy electronics. I'm wondering if you can
start out telling me more about it. takao.someya:
Our group has developed highly conductive rubber using single-walled
carbon nanotubes and we have applied the new materials for truly
rubber-like stretchable integrated circuits. imtracynotstacy:
is this an area that your team has been focused on for a long time?
8:10 AM takao.someya:
Yes, it is. Our group has been working on large-area, flexible,
conformable electronics in a broad sense in the past five years.
Stretchable electronics is a reasonable extension of our research
activities.
8:11 AM imtracynotstacy:
Why is developing large area flexible electronics a key research area
for you? What sorts of uses could this technology be used for?
8:15 AM takao.someya:
This is an important question. We are interested in realizing
electronic artificial skins (e-skins). We made a prototype of flexible
large-area pressure and thermal sensors in 2003. Then, we have made a
little stretchy e-skins in 2005. Now we are tying to make truly rubber
like e-skins in order to cover the freely curved surfaces like robot
bodies. imtracynotstacy: What would this electronic skin do?
8:19 AM takao.someya:
The most advanced robots have several tactile sensors only on the
finger tips. imtracynotstacy: Could you say more about that? What sorts of capabilities would you expect a robot could have with an all-over sensing skin?
8:24 AM takao.someya:
A robot is expected to work in our daily life in the future. It may
help senior persons in beds or play with babies. If robot surfaces are
not entirely covered by e-kins, some robot part could hit a person, but would
not know it. imtracynotstacy: So would these skins have touch sensing only? Or might the skins also "hear" or "see?"
8:27 AM takao.someya:
Animal skins can detect at least pressure and temperature. In the past,
we have tried to make a kind of imitation of animal skins. However, we
can integrate our e-skins with a photo-sensitivity and even more.
In the field of
electronics, it is extremely difficult to realize large-area,
flexible, conformable, electronics that can be applied to curved
surface because the conventional electronics relies on silicon or
other rigid materials.
8:36 AM imtracynotstacy:
Yes, I understand. A rigid surface doesn't bend much. I know other
people are working in this area, too, of making large flexible
electronics. Can you talk a little bit about what makes your team's
work stand out? What are the key things you've done that others have
not yet been able to accomplish?
8:39 AM takao.someya:
In the field of flexible electronics, many research groups are working
on flexible displays such as paper-like displays or e-paper. Of course,
flexible displays are very important; however, our group are looking
for other possibilities beyond displays, which are large-area sensors
and large-area actuators. imtracynotstacy: When you say "beyond displays," what do you mean? Are the flexible electronics different or more complicated? If so how?
8:42 AM takao.someya:
I mean something different from flexible displays. I could say that
almost all the researchers are working of flexible displays; therefore,
I tried to find some new applications in the fields of flexible
electronics. imtracynotstacy: I see. So what aspects of your teams' research is unique?
8:47 AM takao.someya:
Our team is an expert of organic transistors, which are flexible and
can be cheaply manufactured by printing processes. We applied printed
organic transistors for e-skins for the first time. imtracynotstacy:
When you say "printed," what does that mean? Some people reading this
may not be totally aware of the process.
8:51 AM takao.someya:
Organic semiconductors can be
deposited at room temperature by printing machines such as ink-jet
printers. Organic transistors cannot achieve the high-speed performance
of silicon devices but their fabrication cost is much lower, and they
are better-suited for fabrication on large-area, flexible plastic
substrates.
8:53 AM imtracynotstacy:
I see. So theoretically you could have a big printing press with a
sheet of the rubbery material and then print the electronics onto that
sheet? Is that what you're talking about?
8:56 AM takao.someya:
Yes, you are absolutely correct. I started my story from e-skins.
E-skins are new sheet-type devices that can make surfaces intelligent.
Our e-skins may be applied to surfaces of humanoid robots; however,
those can be also applied to other complicated surfaces of objects or
machines.
8:58 AM imtracynotstacy:
The information I read about your work says you're doing it with carbon
nanotubes. Does using nanotubes make creating these stretchy
electronics easier? takao.someya: Yes, nanotubes play an important role to obtain highly conductive rubber.
imtracynotstacy: What's so special about them?
9:01 AM takao.someya:
We used millimeter-long carbon nanotubes. So conductive networks can be
made of so long nanotubes and embedded in a rubber matrix. imtracynotstacy: Are the nanotubes themselves stretchy?
takao.someya: No. Nanotubes are used as conductive dopants. imtracynotstacy: What is a dopant?
9:04 AM takao.someya:
Rubbers are inherently insulators. Therefore, conductive substances are
added to rubber to obtain conductivity. These substances are called
dopants.
9:05 AM imtracynotstacy: I see!So what happens to the nanotubes when the rubber gets stretched?
takao.someya: Ok.Carbon
nanotubes are kinds of conductive spaghetti embedded in rubbers and
form a conductive network. A spaghetti-like conductive network is
deformed if rubber matrix is stretched; however, conductivity does not
change, if the network is not broken.
imtracynotstacy: And just how stretchy can your material get?
9:15 AM takao.someya:
A uniform conductive rubber film can be stretched by 38 percent. When it is
mechanically processed to form a net-shaped structure, it can be
stretched by 134 percent. imtracynotstacy: Wow! That's pretty stretchy.
So what is your team's next step?
9:19 AM takao.someya:
In the current fabrication methods of stretchable integrated circuits,
stretchable wires were not printed although almost all the other
elements are printed. In order to realize cost-competitive processes,
we would like to develop printed stretchable wires or fully printed
stretchable integrated circuits to make surface intelligent. imtracynotstacy: what on earth would you make a stretchy wire from?
9:22 AM takao.someya: A stretchable wire is made from carbon nanotube-based conductive rubbers. imtracynotstacy: It sounds
like carbon nanotubes have or are becoming a big part of your research.
9:27 AM takao.someya:
Yes, indeed. Thanks to carbon nanotubes, conductivity of rubber are now
sufficiently high to apply for wires in integrated circuits. We would
like to improve conductivity and stretchability further.
imtracynotstacy: I look forward to hearing about it when you do! I'll let you get back to your work now.
Thanks so much for taking the time to chat.
takao.someya: I really enjoyed chatting with you. Thanks.
9:29 AM imtracynotstacy: Have a good evening
takao.someya: Have a good day!!
Tags: Carbon Nanotubes, Devices, Electronics, Materials, Plastic,
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