Stepwise waveform generator for autonomous microfluidic control

Controlling fluidic stepwise waveforms is important in many applications of medical science, biology, and chemistry. However, such a control is implemented by automated, yet expensive, dynamic controllers hindering broad use of these systems. This study presents a stepwise waveform generator (SWG) that achieves stepwise pressure variation using constant water-head pressure only. SWG consists of a microfluidic oscillator and a diode pump, autonomously converts constant pressure to pulsatile pressure via the oscillator, and then generates stepwise increasing or decreasing pressures via the diode pump. The step size, and duration time of the pressure step, can be set independently to take values within the range of 215-431 Pa and 26-181 s, respectively. With the use of additional valves, SWG can regulate flow rate, wall shear stress, and reagent concentration, in a stepwise manner, thereby opening new avenues for the applicability of this self-controlled device. (C) 2018 Elsevier B.V. All rights reserved.