BPN 317 Electrospinning for MicroNano Manufacturing Chieh Chang
BPN 317 Electrospinning for Micro/Nano Manufacturing Chieh Chang Prof. Liwei Lin Berkeley Sensor and Actuator Center Department of Mechanical Engineering University of California, Berkeley chieh@me. berkeley. edu © 2006 University of California Prepublication Data Spring 2006
Background • • Growth of nanowires/tubes needs critical conditions Undeterminitic nano-structures Unsuitable for some biodevices Long continuous nanofibers with diameter of less than 100 nm by electrospinning Goals • Mechanisms of electrspinning • Near-field electrospinning for deterministic nanostructures • Nano-devices based on near-field electrospinning • Alignment © 2006 of nanowires and nanotubes University of California Prepublication Data Spring 2006
Setup of NFES High Voltage h Ground Probe Tip Polymer Solution Liquid Jet Collecto r 10 mm Probe Tip Droplet 20 mm • The polymer solution (Polyethylene oxide, PEO) is attached to the tip of the tungsten electrode in a manner analogous to that of a dip pen. • Tungsten tip diameter: 25 mm • Minimum electrode-to-collector gap: 500 mm • Minimum applied voltage: 600 V • Concentration: 3%wt and 5%wt © 2006 University of California Prepublication Data Spring 2006
Experiment Results • Using x-y stage to control the movement of collector Collector moving speed at 5 cm/sec Collector moving speed at 10 cm/sec • Concentration: 5%wt PEO • Electrode-to-collector gap: 1 mm • Applied voltage: 1200 V Collector moving speed at 15 cm/sec Collector moving speed at 20 cm/sec © 2006 University of California Prepublication Data Spring 2006
Experiment Results • Demonstration of controllability Nanofibers are separated 3 mm away from each other under the control of the x-y stage © 2006 University of California Two groups of parallel lines are constructed perpendicular to each other Prepublication Data Spring 2006
Experiment Results • Demonstration of controllability A “U” shape symbol is plotted manually by NFES. © 2006 University of California The three-character “Cal” is manually drawn in a period of 3 seconds Prepublication Data Spring 2006
Future Directions • Investigation on the optimal parameters • More precise and sophisticated tracking control of nanofibers • Integration of electrospinning with micro/nano fabrication • Development of devices based on electrospinning Acknowledgements • Dr. Daoheng Sun for many useful discussions • Ron Wilson for his work on SEM • Soo Jeon for his help with the operation of x-y stage © 2006 University of California Prepublication Data Spring 2006
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