Browsing by Author "Jang, Ling-Sheng"

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Effect of actuation sequence on flow rates of peristaltic micropumps with PZT actuators
(2009-02-01)
Jang, Ling-Sheng
;
Shu, Kuan
;
Yu, Yung-Chiang
;
Li, Yuan-Jie
;
Chen, Chiun-Hsun
Many biomedical applications require the administration of drugs at a precise and preferably programmable rate. The flow rate generated by the peristaltic micropumps used in such applications depends on the actuation sequence. Accordingly, the current study performs an analytical and experimental investigation to determine the correlation between the dynamic response of the diaphragms in the micropump and the actuation sequence. A simple analytical model of a peristaltic micropump is established to analyze the shift in the resonant frequency of the diaphragms caused by the viscous damping effect. The analytical results show that this damping effect increases as the oscillation frequency of the diaphragm increases. A peristaltic micropump with three piezoelectric actuators is fabricated on a silicon substrate and is actuated using 2-, 3-, 4- and 6-phase actuation sequences via a driving system comprising a microprocessor and a phase controller. A series of experiments is conducted using de-ionized water as the working fluid to determine the diaphragm displacement and the flow rates induced by each of the different actuation sequences under phase frequencies ranging from 50 Hz to 1 MHz. The results show that the damping effect of actuation sequences influences diaphragm resonant frequency, which in turn affects the profiles of flow rates.
Simulation and experimentation of a microfluidic device based on electrowetting on dielectric
(2007-12-01)
Jang, Ling-Sheng
;
Lin, Guo-Hua
;
Lin, Yi-Liang
;
Hsu, Chih-Yuan
;
Kan, Wai-Hong
Electrowetting on dielectric (EWOD) moving fluid by surface tension effects offers some advantages, including simplicity of fabrication, control of minute volumes, rapid mixing, low cost and others. This work presents a numerical model using a commercial software, CFD-ACE+, and an EWOD system including a microfluidic device, a microprocessor, electric circuits, a LCD module, a keypad, a power supply and a power amplifier. The EWOD model based on a reduced form of the mass conservation and momentum equations is adopted to simulate the fluid dynamics of the droplets. The EWOD device consists of the 2 x 2 mm bottom electrodes (Au/Cr), a dielectric layer of 3,000 angstrom nitride, 500 angstrom Teflon and a piece of indium tin oxide (ITO)-coated glass as the top electrode. The complete EWOD phenomenon is elucidated by comparing simulation with the experimental data on droplet transportation, cutting and creation. In transportation testing, the speed of the droplet is 6 mm/s at 40 V-dc. In addition, the droplet division process takes 0.12 s at 60 V-dc in the current case. Finally, a 347 nl droplet is successfully created from an on-chip reservoir at 60 V-dc.