A normally-open, wide-range, proportionally controlled 3D-printed microvalve using a piezo stack microactuator

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Abstract

Microvalves are useful components for several microfluidic applications in which they control the fluid flow in a microfluidic system. Most microvalves to date are made by using silicon micro-machining, which is a complex manufacturing process, or soft lithography using Polydimethylsiloxane (PDMS) which has a high gas permeability. Next to that most microvalves in literature have small actuation forces resulting in small pressure ranges and large leakages at low pressure levels. In this paper, a normally open microvalve which is fabricated by only using 3D printing techniques with a bio-compatible resin is presented, making it more easy and accessible to manufacture. The novelty is the integrated micro-channels, membrane and microfluidic connections in a single 3D printed piece. The utilized actuator is a commercially available piezo stack, which has a displacement of 34 µm at 150V. Due to its large actuation force the microvalve can modulate fluids from -600 to 600 mbar, with measured flow-rate levels between 0-90 µl/min and projected flow-rate levels between 0-410 µl/min. In fully closed state the leakage-rate of the microvalve is 1.67 µl/min at 600 mbar, with a static power consumption of 442.5 mW. Subsequently it is shown that after using higher clamping torques (> 0.7 Nm) the microvalve can operate leakage free up to 1.5 bar. Additionally a 3-to-1 fluid selector is designed using three microvalves, which can be integrated into a portable microfluidic platform for Organ-on-Chip (OoC) applications.