Three-Dimensional, Flexible Nanoscale Field-Effect Transistors as Localized Bioprobes

Nanoprobes of Cell Potential Direct electrical measurements of cell potentials usually face design compromises. Microelectrodes probe within the cytosol of cells but have a minimum size (hundreds of nanometers in width) for obtaining useful signals. Nanoscale field effect transistors (FETs) can have an active probe size of only tens of nanometers but generally allow only the outer cell potential to be measured. Tian et al. (p. 830 ) fabricated nanowires in which kinks could be introduced to create a sharp probe tip pointing away from the fabrication substrate. Coating the tip with a phospholipid bilayer allowed the probe to be inserted through the membranes of beating cardiac cells, where it could be used to follow temporal changes in cell potential.