Title :
A Piezoactuated Droplet-Dispensing Microfluidic Chip
Author :
Ahamed, Mohammed Jalal ; Gubarenko, Sergey I. ; Ben-Mrad, Ridha ; Sullivan, Pierre
Author_Institution :
Dept. of Mech. & Ind. Eng., Univ. of Toronto, Toronto, ON, Canada
Abstract :
A microfluidic dispensing device that is capable of generating droplets with volumes varying between 1 nL and 50 pL at an ejection frequency of up to 6 kHz is presented. In this device, a piezoactuator pushes onto an elastic membrane via piston tips; the mechanical bending of the membrane generates a pressure pulse pushing droplets out. An analytical model was developed solving bending characteristics of a plate-actuated fluidic dispensing system and used to calculate the displaced volume. The model was extended to perform stress analysis to find the optimum piston tip radius by minimizing design stresses. The optimum piston tip radius was found to be 67% of the chamber radius. The actuation force estimated using the analytical model was then used as input to a finite element model of the dispenser. A detailed numerical analysis was then performed to model the fluid flow and droplet ejection process and to find critical geometric and operating parameters. Results from both models were used together to find the best design parameters. The device contains three layers, a silicon layer sandwiched between two polydimethylsiloxane (PDMS) polymer layers. Silicon dry etching, together with PDMS soft lithography, was used to fabricate the chip. PDMS oxygen plasma bonding is used to bond the layers. Prototypes developed were successfully tested to dispense same-sized droplets repeatedly without unwanted droplets. The design allows easy expansion and simultaneous dispensing of fluids.
Keywords :
bending; drops; finite element analysis; membranes; microfluidics; piezoelectric actuators; soft lithography; stress analysis; PDMS oxygen plasma bonding; PDMS soft lithography; droplet ejection; droplet generation; elastic membrane; finite element model; fluid flow; mechanical bending; microfluidic dispensing device; numerical analysis; piezoactuated droplet-dispensing microfluidic chip; piezoactuator; piston tips; plate-actuated fluidic dispensing system; polydimethylsiloxane polymer layers; pressure pulse; silicon dry etching; silicon layer; stress analysis; Deoxyribonucleic acid; droplet; ejection characteristics; microdispenser; microfluidics; piezoactuator; plate deflection;
Journal_Title :
Microelectromechanical Systems, Journal of
DOI :
10.1109/JMEMS.2009.2036866