Fig. 3: Microfluidic transistors enable timing operations and smart dispenser circuits for autonomous single-particle manipulation.

a, Circuit schematic for a sequential delay timer, comprising many cascaded low-pass filters, amplifiers and level shifters. b, A step signal applied to P_start at time t = 0 propagates through the circuit blocks, generating controllable time intervals to trigger sequential fluidic events. Capacitance values were selected to time out five fluidic events sequentially with differing intervals. Triggered pressure signals for three trials of this circuit are overlaid and plotted with mean interval duration shown. c, Circuit schematic for a ring oscillator comprising five amplifiers and five level shifters. d, The ring oscillator spontaneously generates square waves at the output of each inverter, separated in phase by a fifth of a period. The oscillator signals were measured for several minutes, and 63 unit intervals of each signal are overlaid and plotted in the eye diagram. e, Overview of the smart dispenser operation, depicting the core microfluidic trap in different states as it senses and dispenses a single particle (scale bars, 50 μm). f, Circuit schematic of the smart dispenser comprising several circuit blocks and the microfluidic trap (purple). g, Deterministic single-particle ordering and concentration using the smart dispenser. This dispenser configuration has the Trig and Sense lines directly connected, so that individual particles are sensed and immediately dispensed into the output channel. Pressure signals from the trap itself (P_plug) and the trigger (P_Trig) for a run of n = 230 particles are shown, along with a representative dispense event to observe the individual dynamics (red inset). h, Histograms of input and output particle spacing when using the smart dispenser in this configuration, showing a 6-fold drop in the spacing mean (indicating particle concentration) and a 17-fold drop in the spacing standard deviation (indicating particle ordering).