Organic Materials May Be Wave Of The Future In Digital Signal Processing

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Organic Materials May Be Wave Of The Future In Digital Signal

Processing

ScienceDaily*

(Apr. 7, 2008) — Fungi processing audio signals. E. Coli storing

images. DNA acting as logic circuits.

http://www.sciencedaily.com/releases/2008/04/080407153030.htm

It's possible, and in some cases, it's already happened. In any

event, performing digital signal processing using organic and

chemical materials without electrical currents could be the wave of

the future — or so argue Sotirios Tsaftaris, research professor of

electrical engineering and computer science, and Aggelos

Katsaggelos, Ameritech Professor of Electrical Engineering and

Computer Science, in their recently published " point of view " piece

in the March 2008 edition of Proceedings of the IEEE (Institute of

Electrical and Electronics Engineers.)

Digital signal processing uses mathematics and other techniques to

manipulate signals like images (natural medical, and others) and

sound waves after those signals have been converted to a digital

form. This processing can enhance images and compress data for

storage and transmission, and such processing chips are found in

cell phones, iPods, and HD TVs.

But over the past 10 years, scientists and engineers around the

world have experimented with performing signal processing using

different materials. In their piece, Tsaftaris and Katsaggelos

describe these experiments while stirring the engineering community

towards " a possible not-so-electronic future " of digital signal

processing.

For example, scientists and engineers have shown that certain

chemicals, when mixed in a solution, don't react until light is

projected through them. So if you project light through a

transparency image, these chemicals can record the image. When the

chemicals are stimulated by light and controlled by the acidity of

the mixture, basic image transformations like contour enhancement

can happen.

But such processing tasks extend beyond chemicals to organic

materials. Artist/scientist Cameron found that out after he

used audio CDs as substrates to grow fungi. He put the fungi-laced

CDs in a CD player and found that the optically recorded sound was

distorted by the fungi — and the fungi growth patterns were

dependent on the optical grooves recorded on the CD.

" The bacteria reacted to the recorded information, and the audio

track was 'processed' by the grown fungus, " Tsaftaris says. " That is

essentially bacterial signal processing. "

Using bacteria to process signals has even spurred a competition –

the International Genetically Engineered Machine Competition at the

Massachusetts Institute of Technology, where undergraduate students

compete to design biological systems that can perform simple

computations. In 2005, a group modified E. coli cells to react to

light, and the students created a layer of these bacteria that could

perform edge detection of an image – a basic processing task.

Tsaftaris's and Katsaggelos's research includes studying the use of

DNA for digital signal processing. DNA strands can be used as input

and processing elements, and, it turns out, DNA is an excellent

medium for data storage. Digital samples can be recorded in DNA,

which can be kept in a liquid form in test tubes to save space. DNA

can also be easily replicated using common laboratory techniques,

and such a database could be easily searchable, no matter how large

it is.

" It becomes a very attractive solution, " Tsaftaris says.

Though science is still years away from this possibility, engineers

have created useful algorithms in their pursuit of the technology.

Such algorithms have been used, for example, to better detect

disease. But Tsaftaris hopes for a day when organic digital signal

processing will allow for the implementation of the so-called " fast

Fourier transform " — a widely-used method of extracting useful

information from sampled signals that Tsaftaris calls the " holy

grail " of DNA signal processing.

" The cost and delivery time of DNA synthesis is being reduced

exponentially, this making data input elegant and economical, "

Tsaftaris and Katsaggelos write in the paper. " DNA equipment is

getting even…cheaper, such that anybody can process the signals in

the office and later at home pull out their Discovery's DNA Explorer

Kit or CSI's DNA Lab Kit and with their kids (or alone, satisfying

their inner child) manipulate and analyze DNA in their living room.

But of course don't forget to feed the bacteria that nurture your

precious jazz collection. "