Major Motor Breakthrough and More

We have determined that the type of motor that would allow for our home-made syringe pump to work would be a stepper motor. This motor does not turn constantly but rather turns in minute steps as a results of a gear-like disc a a magnetic attraction. This will allow for a constant and slow flow rate./

Figure 1: An animated image showing the movement of a stepper motor. (See reference 7)

Another major change is that the barrel of the electrospinning device will be square rather than cylindrically shaped.

The existence of a potential difference between the fiber and the surface with which it comes into contact necessitates that the fibers be spun directly on a piece of grounded metal. Other wise, a surface must be place in the way of the fibers as they are on the path to the metal plate.

More Changes

In order for the device contain all the necessary components, it will need a lot of space. For this reason, we have decided to go back to the original gun design but with he addition of a rear compartment where the motor will be housed.
In addition, we have examined many options and have decided it would be extremely difficult to generate a high in such a small device, so the device must be charged with an external generator.
Pictures to come.

Final Plans and Changes

It has been decided that the electrospinning device will take more of a pen shape rather than that of a gun. This design would eliminate the unnecessary turn in the device which would require complicated circuitry. This way, the components of the device will be placed in a linear fashion along a tube.

A sliding hollow cylinder will be used as the syringe case for easy removal and insertion (Figure 1).

A ring will be used instead of a collector plate to guide the fibers onto any desired surface (Figure 1).

The button of the device should active both the motor (the syringe pump) and the applied voltage at the same time. Some potential button designs are pictured in Figure 2.

 Figure 1: Designs for a ground, a syringe tube, and a circuit.

Figure 2: Possible button mechanisms.

Lab Test

On Wedneday morning, the group began testing at a electrospinning lab with one our advisors, Marjorie Austero. The parameters for the setup were as follows.

Solution: 5 wt. % polyethylene oxide in water

needle diameter: 0.5 micrometers

flow rate: 1.3 ml/hr

21 gauge needle

At the start of the test the temperature was 22.9 degrees celcius with 41% relative humidity.

Approx 5 ml of solution spun for almost five hours.

A video has been included to display the physical appearance of the setup. We now have to finalize our design to implement these components into our device. 

Important Info to Help With Lab Parameters

Here are two significant quotes I came upon in the articles by Frenot et al, and Reneker & Yarin, respectively (full references found under "References" tab).

"They produced a skin mask by directly electrospinning fibers onto the skin surface in order to protect or heal eventual wounds."

"A voltage at which the flow out of the drop was equal to the set flow rate into the drop could be found experimentally by adjusting the voltage to make the size of the drop constant in time."

The following is a graph from the latter article showing the effects of various parameters including flow rate, voltage, and current.

Electrospinning In Action

Last Friday the group visited a Drexel electrospinning lab in the Center for Automated Technologies. A few students were there to demonstrate their work and the electrospinning process. The fibers at this lab were used to create efficient capacitors by creating very thin fibers with pores in them.