Cells have been grown on arrays of microscale electrodes, which can both inject and record cellular currents, to study their electrical activity. Three recent papers have measured cellular currents using much smaller, nanoscale electrodes. Robinson et al. fabricated electrodes made of doped, conducting silicon ∼150 nm in diameter and 3 μm high, whereas Xie et al. worked with platinum electrodes ∼150 nm in diameter and 1–2 μm high. In both studies, the amplitude of the action potentials recorded from neurons or cardiomyocytes was only ∼10% of that measured by patch clamp, the gold-standard electrophysiology technique, although unlike patch clamp, the nanoscale electrode arrays allow recording of many cells over several days. In contrast, Duan et al. achieved much higher sensitivity by using a silicon field-effect transistor (FET) with a branched nanotube, measuring ∼55 nm at the tip and 1–1.5 mm in height. With this approach, the amplitude of action potentials was similar to that seen with patch clamp. This FET-based active recording requires only a single nanotube, in contrast to the multiple, larger nanowires contained in each passive electrode in the other two studies. Compared with microscale electrodes, nanoscale electrodes are less damaging to cells and could be arrayed in closer proximity to increase the resolution of the technique. (Nat. Nanotechnol. 7, 180–184, 2012; Nat. Nanotechnol. 7, 185–190, 2012; Nat. Nanotechnol. 7, 174–179, 2012)