Piezoelectric Normally Open Microvalve with Multiple Valve Seat Trenches for Medical Applications

Abstract

Microfluidic systems for medical applications necessitate reliable, wide flow range, and low leakage microvalves for flow path control. High design complexity of microvalves increases the risk of possible malfunction. We present a normally open microvalve based on energy-efficient piezoelectric actuation for high closing forces and micromachined valve seat trenches for reliable valve operation. A comprehensive investigation of influencing parameters is performed by extensive fluidic 3D finite element simulation, derivation of an analytical closed state leakage rate model, as well as fabrication and test of the microvalve. Additional valve seat coating and a high force actuator are introduced for further leakage reduction. The microvalve has a wide-open flow range as well as good sealing abilities in closed state. Extensive fatigue tests of 1 × 106 actuation cycles show that additional coating of the valve seat or increased actuator strength promote sealing performance stability. Analytical calculations of leakage are suitable to estimate experimentally obtained leakage rates and, along with computational fluidic dynamic (CFD) simulations, enable future microvalve design optimization. In conclusion, we demonstrate that the presented normally open microvalve is suitable for the design of safe and reliable microfluidic devices for medical applications.

Microfluidic Delivery of High Viscosity Liquids Using Piezoelectric Micropumps for Subcutaneous Drug Infusion Applications

“…The flow Q V through restriction at the valve seat is given by the laminar, radial gap flow of a round plate valve [27] : \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*} {Q}_v = \frac{{\pi \ h_v^3}}{{6\ \eta \ ln\ \frac{{{r}_1}}{{{r}_0}}\ }}{\mathrm{\Delta }}{p}_v = \ \frac{1}{{{R}_{\rm valve}}}{\mathrm{\Delta }}{p}_v \tag{6} \end{equation*}\end{document} …”

“…The flow QV through restriction at the valve seat is given by the laminar, radial gap flow of a round plate valve [27]:…”

Multi-state, three-way, normally open mini valve based on 3D printed flexible magnets using origami-inspired magnetization

“…The piezoelectric and electrostatic actuators' size is usually small, and they produce strong forces with little deflection [9][10][11]. Nevertheless, their high operating voltage is a shortcoming (>100 V) [12][13][14]. Though mini valves based on shape-memory-alloy and thermal actuators may obtain a large stroke with low voltage (<50 V), they demand a long response time (>1 s) and considerable energy consumption [15][16][17][18].…”