MadSci Network: Computer Science
Query:

Re: are biological based traces possible

Date: Wed Jan 29 13:47:31 2003
Posted By: Tomas Izo, Graduate Student
Area of science: Computer Science
ID: 1043235141.Cs
Message:

Hello!

This is indeed an interesting question, and one which I can't answer in a very quantitative way, i.e. in terms of the cost of circuit fabrication. However, I'll try to point you in some useful directions.

Before I begin, I should point out that I enlisted the help of my friend Kathy Aidala, who is an applied physicist at Harvard. Some of what I write comes from Kathy or is based on our conversation.

There are a number of points that come to mind when considering what you're suggesting; here are a few of them:

1. I can think of two ways to use bacteria waste in fabricating circuits: you could either use the bacteria to fabricate the circuit for you or you could merely have the bacteria manufacture the materials which you will then use for the circuit. I'm going to assume that you meant the former just because it sounds more interesting to me. Concerning the latter, I don't know how to estimate whether it could be cheaper, but consider this: if you want the bacteria to produce conductive waste, presumably you need to feed them some of the materials that you want to have in your circuit. You need to think of issues such as low resistivity and low power dissipation so that your circuit has the properties you expect from it. These materials may not come cheap at all. What's more, you have the additional cost of keeping the bacteria alive and plentiful, especially if you want to manufacture circuits on a large scale.

2. Let's go back to the idea of using the bacteria to make the circuits for us. I haven't been able to find much research directly related to this, but I have found some that you might be interested in checking out. The Nanotechnology R&D Group at NASA (link) has a project that involves genetically engineering a type of microbes they call "thermophiles" (because their natural habitat is very hot) to produce proteins with interesting properties. One such protein, called HSP60, has the ability to self-assemble into nanometer-scale structures. Furthermore, these structures can then capture conductive and semiconductive particles. Theoretically, such structures could then be used in "logic and memory-based devices." Check out the following links for more details:

Andrew McMillan, one of the Nanotechnology researchers
Jonathan Trent, another member of the Nanotechnology group

3. Hypothetically, I could also envision someone genetically engineering bacteria to follow some sort of chemical gradient and leave a trail of conductive waste. Some bacteria exhibit gradient-following behavior naturally when searching for food. For instance, E. coli exhibit what is often called "twiddle and run" motion, which enables them to follow the food gradient: the direction in which the concentration of food increases the most. However, they don't follow it precisely, which is something you might require if you wanted to fabricate circuits. Thus it is questionable whether this type of fabrication is even feasible, not to mention cheap. Finally, it would only be useful for printed circuits because the scale of microchips is just too small.
For more information on E. coli motion, see this link (scroll down to "Bacterial Motility")

4. Straying a little further from your question, some research groups are interested in what is referred to as "biomimetics." One such group is the Whitesides Group at Harvard. They describe biomimetics as essentially "the abstraction of good design from nature" and their research includes creating biologicailly-inspired self-assembling structures, including functioning circuits. Check out their webpage for more information (Click on Research, then Biomimetics). I hope this helped!

Tomas
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