Week 7 - Results Analysis (1st Variable) and Taylor Cone

Figure 25. 3% PEO solution spun  at 10 cm [16]

A lab conducted by the Department of Electrical and Computer Engineering at the University of Waterloo had similar data and the engineers that conducted a similar experiment which had conclusions that mirrored ours. The SEM picture on the left shows a 3% PEO solution spun at a distance from 10 cm. The beading occurred just like in our 12 cm spinning. The fibers were at a similar length. The average fiber diameter for their experiment at this distance was 55.65 nm, while ours was 49.52 nm. They concluded that 10 cm had the least beads formed, had the right diameter fibers needs for the aliginate gel formation, and it was the most consistent with a standard deviation in diameter 9.87 nm. The beads formed because of a taylor cone and the voltage that ran through the solution.



Figure 26. Effect of voltage on Taylor Cone [16]



The voltage change drastically affects whether or not beads or fibers form. The lower the voltage, the more beads will form from the spinning. If the voltage is between 3 kV to 7 kV, there will be some beads and some fibers. If the voltage is above 7 kV, the jet will mostly form fibers. A Taylor Cone is a jet of charged particles that emanates above a threshold voltage. The name Taylor Cone is named after Sir Geoffrey Taylor whom in 1964 coined the term before electrospray was "discovered" [11]. As the voltage is increased the effect of the electric field becomes more prominent and as it approaches exerting a similar amount of force on the droplet as the surface tension does a cone shape begins to form with convex sides and a rounded tip.