Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Dynamic Characterization of a Valveless Micropump Considering Entrapped Gas Bubbles J. Heat Transfer. 2013;135(9): doi: / Schematic illustration of a nozzle-diffuser piezoelectric valveless micropump. (a) Cross-sectional view of a nozzle-diffuser piezoelectric valveless micropump. (b) “Supply mode” during pumping. Liquid flows inward to the pump chamber through microchannels, when channel 1 works as a diffuser and channel 2 works as a nozzle. (c) “Pump mode” during pumping. Liquid flows outward to both the inlet and the outlet through microchannels, when channel 1 works as a nozzle and channel 2 works as a diffuser. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Dynamic Characterization of a Valveless Micropump Considering Entrapped Gas Bubbles J. Heat Transfer. 2013;135(9): doi: / Structure of a nozzle-diffuser piezoelectric valveless micropump. (a) Micropump after assembling. (b) Explosive view of a nozzle- diffuser piezoelectric valveless micropump. The microchannels are micromachined on PMMA boards. The top layer, the bottom layer, a piezoelectric membrane, an inlet and an outlet pipe are assembled with glue. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Dynamic Characterization of a Valveless Micropump Considering Entrapped Gas Bubbles J. Heat Transfer. 2013;135(9): doi: / Pressure-loss coefficient for diffuser and nozzle. The same microchannel will work as diffuser or nozzle in different modes. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Dynamic Characterization of a Valveless Micropump Considering Entrapped Gas Bubbles J. Heat Transfer. 2013;135(9): doi: / Experiment setup for the gas bubble observation and pressure pulsation measurement. The 250 Hz 80 V square wave signal is used to drive the piezoelectric membrane. A pressure transducer and the high-speed video camera are adopted for the pressure measurement and image acquisition. The data acquisition board and PC are used for data collection. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Dynamic Characterization of a Valveless Micropump Considering Entrapped Gas Bubbles J. Heat Transfer. 2013;135(9): doi: / Experimental results and numerical data of gas bubbles and pressure pulsations. (a) Picture of micropump when gas bubbles occupy about 1/30 of the whole chamber volume (about 1.5 μL). (b) Comparison of simulation result and experimental data when gas bubbles occupy about 1/30 of the chamber volume. (c) Picture of micropump when gas bubbles occupy about 1/8 of the whole chamber volume (about 5 μL). (d) Comparison of simulation result and experimental data when gas bubbles occupy about 1/8 of the chamber volume. (e) Picture of micropump when gas bubbles occupy about 3/8 of the whole chamber volume (about 15 μL). (f) Comparison of simulation result and experimental data when gas bubbles occupy about 3/8 of the chamber volume. Figure Legend:

Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Dynamic Characterization of a Valveless Micropump Considering Entrapped Gas Bubbles J. Heat Transfer. 2013;135(9): doi: / Comparison of simulation results with different gas bubble volume. (a) Transient flow rate of the nozzle-diffuser valveless micropump when gas bubbles occupy 0%, 3.33%, 12.5%, and 37.5% of the whole pump chamber volume. (b) Accumulated flow rate (pumped liquid through outlet) for 2 s of the nozzle-diffuser valveless micropump when gas bubbles occupy 0%, 3.33%, 12.5%, and 37.5% of the whole pump chamber volume. Figure Legend: