Individual neuron electrical activity measured with carbon nanotubes

MIT Technology Review : A team of researchers at Duke University in North Carolina has created a probe that is small enough to enter a single neuron, and sensitive enough to measure variations in the cell’s electrical activity. The 1-mm-long and 5- to 10-μm-diameter probes are made of tangled carbon nanotubes attached to the end of a tungsten wire and covered with a thin insulating film. The researchers used a beam of focused ions to remove the insulation from the tip and shave it to a very fine point. The design will allow for even longer and thinner probes in the near future. The researchers tested the probes on dissected slices of still-living mouse brain tissue and on anesthetized mice. Although they were able to detect signals in the slices, they could not read from the live mice. The researchers attribute that failure to the size of the current probes, which may still be too large to penetrate nonneural tissue. The ability to read individual neuron cell activity will help researchers better understand how signals are passed between cells.