Graduate student Mingjing Ha working with Optomec, Inc. and Northwestern University collaborators (Mark Hersam) has demonstrated low voltage, fast carbon nanotube (CNT) circuits printed on flexible plastic substrates. The circuits are fabricated by aerosol jet printing from a liquid dielectric ink (ion gel) and a purified semiconducting CNT ink (Northwestern). The printed semiconducting CNTs form the channels in thin film transistors and printed circuits. A five-stage ring oscillator operating at 2 kHz with a 3 V supply voltage was demonstrated, corresponding to a signal delay time of 50 ms. This is the shortest delay time reported for a printed circuit on plastic operating below 3 V, as shown in the figure.