title: The Combination of Micro Diaphragm Pumps and Flow Sensors for Single Stroke Based Liquid Flow Control.
abstract: With the combination of micropumps and flow sensors, highly accurate and secure closed-loop controlled micro dosing systems for liquids are possible. Implementing a single stroke based control mode with piezoelectrically driven micro diaphragm pumps can provide a solution for dosing of volumes down to nanoliters or variable average flow rates in the range of nL/min to μL/min. However, sensor technologies feature a yet undetermined accuracy for measuring highly pulsatile micropump flow. Two miniaturizable in-line sensor types providing electrical readout-differential pressure based flow sensors and thermal calorimetric flow sensors-are evaluated for their suitability of combining them with mircopumps. Single stroke based calibration of the sensors was carried out with a new method, comparing displacement volumes and sensor flow volumes. Limitations of accuracy and performance for single stroke based flow control are described. Results showed that besides particle robustness of sensors, controlling resistive and capacitive damping are key aspects for setting up reproducible and reliable liquid dosing systems. Depending on the required average flow or defined volume, dosing systems with an accuracy of better than 5% for the differential pressure based sensor and better than 6.5% for the thermal calorimeter were achieved.
authors.affiliation: Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT, 80686 Munich, Germany. christoph.jenke@emft.fraunhofer.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Jenke
authors.affiliation: Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT, 80686 Munich, Germany. j.palleja.rubio@gmail.com.
authors.forename: Jaume
authors.initials: J
authors.lastname: Pallejà Rubio
authors.affiliation: Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT, 80686 Munich, Germany. sebastian.kibler@emft.fraunhofer.de.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kibler
authors.affiliation: Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT, 80686 Munich, Germany. johannes.haefner@emft.fraunhofer.de.
authors.forename: Johannes
authors.initials: J
authors.lastname: Häfner
authors.affiliation: Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT, 80686 Munich, Germany. martin.richter@emft.fraunhofer.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Richter
authors.affiliation: Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT, 80686 Munich, Germany. christoph.kutter@emft.fraunhofer.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Kutter
keywords: damping; differential pressure based flow sensor; flow control; flow sensor; micropump; sensor velocity; single stroke; thermal flow sensor