News at Princeton

Tuesday, April 22, 2014

Multimedia: Featured

Plastic electronics


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Engineering professor Yueh-Lin (Lynn) Loo describes some of the potentially life-changing uses for these malleable materials. Read more.


Video Closed Captions

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Lynn Loo:
Plastic electronics are electronic devices in which the active components are made out

Lynn Loo:
of carbon-based materials, so these are plastics, polymers or small molecules. The reason you

Lynn Loo:
want to make plastic electronics is because you want to make use of the attributes of

Lynn Loo:
these plastic materials. These include their mechanical flexibility, they're lightweight,

Lynn Loo:
they can be produced with tunable properties, and this is something you can't easily do

Lynn Loo:
with inorganic materials. My name is Yueh-Lin Loo, and I work in the field of plastic electronics.

Lynn Loo:
In the field of plastic electronics, it all starts with chemistry. We need to make or

Lynn Loo:
synthesize new materials that are conductive or semi-conductive, so they have the electrical

Lynn Loo:
properties that we would like, so that when we incorporate them into electronic devices,

Lynn Loo:
they're active. In our group, some of the researchers make new materials, some of the

Lynn Loo:
researchers characterize the structures of these materials, and some of them incorporate

Lynn Loo:
these materials to understand their potential in applications like transistors and solar cells

Lynn Loo:
Polyaniline is a conducting polymer that changes color. Here, this color change

Lynn Loo:
is triggered by applying a voltage to the sample. The potential applications for polyaniline,

Lynn Loo:
in addition to being electrodes, is that we can use it as electrochromic displays, as

Lynn Loo:
well as sensors that change color when it's exposed to a specific chemical or reagent.

Lynn Loo:
We use a process called spin coating to make thin layers of these compounds. The layers

Lynn Loo:
end up to be about a hundred nanometers thick. That's about a thousand times thinner than my hair.

Lynn Loo:
Here, we examine the films we make under the microscope to see how the crystals grew during

Lynn Loo:
spin coating. We try to control the size of the crystals in the film.

Lynn Loo:
The bigger the crystals, the better the devices will turn out.

Lynn Loo:
To make the devices, we have to make electrical contact to the film by evaporating gold.

Lynn Loo:
Gold is evaporated through a mask. The pattern of the mask determines where gold is coated.

Lynn Loo:
After the placement of the mask, we put the sample in the gold evaporator.

Lynn Loo:
Alternatively, we can evaporate gold electrodes on a clear silicone rubber stamp, and laminate the rubber

Lynn Loo:
stamp onto the polymer film to make our devices.

Lynn Loo:
The structure of the devices depends on their function. In my opinion, their beauty derives

Lynn Loo:
from their functionality. Compared to inorganics like silicon, plastics have unique attributes.

Lynn Loo:
These include their lightweightness, their mechanical flexibility, their potential low

Lynn Loo:
cost, and their tunability in terms of their properties. So, to incorporate all these attributes

Lynn Loo:
into electronic devices would be really nice.

Lynn Loo:
The field's really exciting because it's a young field, and it's growing, and it's directly

Lynn Loo:
tied to applications that can have direct implications on the quality of our lives.

Lynn Loo:
Imagine electronic wallpaper that changes patterns from green stripes to pink polka

Lynn Loo:
dots at a click of a switch. Imagine tinted windows that can also generate power during

Lynn Loo:
the day. Imagine disposable sensors that would change color if the water source is contaminated.

Lynn Loo:
Or yet, think of smart plastic patches that can monitor your health and deliver medication

Lynn Loo:
when you're sick. The possibilities are endless.

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