NACHIP's core achievement was to develop a working interface between the living tissue of individual neurons and the inorganic compounds of silicon chips. With the help of German microchip company Infineon, NACHIP placed 16,384 transistors and hundreds of capacitors on a chip just 1mm squared in size. The group had to find appropriate materials and refine the topology of the chip to make the connection with neurons possible.
Biologically NACHIP uses special proteins found in the brain to essentially glue the neurons to the chip. These proteins act as more than a simple adhesive, however. "They also provided the link between ionic channels of the neurons and semiconductor material in a way that neural electrical signals could be passed to the silicon chip," says Vassanelli. Once there, that signal can be recorded using the chip's transistors. What's more, the neurons can also be stimulated through the capacitors. This is what enables the two-way communications.
There is more info on this at new scientist The researchers began experimenting with snail brain cells before moving on to rat neurons. Mammal neurons are smaller and more complex. The team had to tinker with the neurons themselves to increase the strength of the connection between cells and the chip. Firstly, the researchers genetically modified the neurons to add more pores. Secondly, they added proteins to the chip that glue neurons together in the brain, and which also attract the sodium pores. "It should be possible to make the signals from the chip cause a neuron to alter its membrane and take up a new gene, or something that switches one off," says Vassanelli. "Now the chip has been developed, we plan to use it to try and switch genes on and off."
A compound that would turn off a gene, or the DNA for a new one, could be added to the dish containing the wired-up neurons.
The new technology could enable very advanced and sophisticated drug screening systems for the pharmaceutical industry in the near term. Long term it could allow non-organic enhancement of brains.