Conversations with Cells

Researcher: Hello? Hello, cell?

Cell: …

Researcher: Cell, are you there?

Cell: I can’t hear you…speak up!

Bionics all boils down to communication. We’re using technology to try to talk to living cells—perhaps to translate sounds into information a deaf person’s brain can understand (like in the Cochlear implant), or to sweet-talk cells into growing across a gap they would normally balk at (like in spinal cord repair).

Language barrier

That means joining up the soft and squishy world of biology with the hard and dry world of electronics. Unfortunately, cells and silicon don’t get on too well—they’re built of different stuff and speak different languages. We have to use other materials to make the connection.

Luckily, there is a class of materials—known as organic conductors—which fit the bill. These are polymers made of carbon, which can also carry electricity—like a conducting plastic. On the one hand, they can carry electricity, just like electrical wires. On the other, they function in a liquid environment by giving out and receiving small molecules—just like neurons do. And, because the organic conductors and the cells are made of the same kind of stuff, they get on like a house on fire.

The problem is, cells are very small.

We can’t make devices from organic conductors which are small enough for a one-on-one conversation.  A lot of groups around the world, including us here at ACES, are trying to make new connections from organic conductors that are small enough to connect with individual neurons.

We’ve just written a review of the progress in this field. We focus on a nanoprinting technique which can draw patterns using a small pointed stick—it’s just like a pen on paper except shrunk down one thousand times. This is …enough that it doesn’t damage the polymers, and it can also achieve the resolution we need.

During my PhD I developed several methods of printing conducting electrodes at nanoscales. The electrode I drew were so small they were technically invisible (in that you can’t view them using visible light, no matter how powerful your microscope is).

I enjoyed drawing my own signature at 0.006 pt font size (nano graffiti). Printed on this scale, you could squeeze the text from a roomful of books on a grain of rice. After developing a new method to print platinum metal at very small scales, I demonstrated it, in the published paper, by printing a microelectrode on a strand of my own hair (the ‘platinum blonde’ experiment).

As we learned when putting this review together, there’s been a lot of exciting work on making these small electrodes. The next step will be to integrate them into working devices.

Image: A neuron growing on a silicon chip. Unfortunately, cells and silicon don’t get on too well together. Source: Fromherz Group, Max Planck Institute