Electrospinning first mat

On Wednesday, April 25, the group was able to produce the first nano-fibrous mat sample in the lab. Aided by the group advisor, Marjorie Austero, we gained experience with the electrospinning equipment and working in a lab environment. Conditions in the lab prohibited spinning under our predetermined parameters. Critical factors like solution composition, solution flow rate, and collection plate distance had to be re-evaluated before a consistent production of fibers was attained. The following chart contains the predetermined conditions, as well as the actual experimental conditions that successfully produced fibers.

Lab Parameters and Conditions
Parameter	Predetermined	Experiment 1
Solution Composition	5% PEO 500,000	3% PEO 900,000
Flow Rate	0.2 mL/hr	0.5 mL/hr
Needle Diameter	0.6mm	14.5mm
Voltage	15 kV	15 kV
Collection Distance	20 cm	11 cm
Time Spinning	est. 3-5 hrs	3 hours
Independent Parameters
Air Temperature		22.8 C
Humidity		22%

(Table 1- The table contains the theoretical parameters determined before working in the lab, as well as actual conditions experienced during experimentation.)

The theoretical parameters chosen were based upon a study that analyzed various components of PEO in water. One major difference between the study and our experiment was the ambient humidity. In the study, testing took place in 50% relative humidity, whereas in our lab, the humidity was much lower at 22%. Because humidity was very low, and the needle diameter was much larger than intended, the theoretical conditions prepared did not successfully spin fibers.

In order to compensate for unexpected lab conditions, the solution was changed to a heavier polymer at a lower concentration. In addition, the flow rate and collection distance had to be adapted before fibers could be generated. Under these conditions, a nanofiber mat was produced after 3 hours time spinning. The mat will be prepared for observation under the scanning electron microscope (SEM) in the beginning of next week. Once the SEM imaging is obtained, analysis of fiber diameter and pore size of the mat can occur. With this information, the spinning parameters again be adapted to further optimize the filtration properties for the next mat we create. 

Moving into Week 4: Design Specifications and Lab Work

As week 4 begins, the team has been busy researching our approach to the filtration problem. Polyethylene Oxide has been assigned by our adviser for us to spin. Polyethylene Oxide has been spun in the lab many times and can be easily spun when dissolved in water. The parameters for the setup had to be researched in order to give a direction to our lab work. There are several parameters that must be taken into account for the process to work efficiently. These parameters include the distance between the needle and the collector, the voltage, humidity, area of the target on the collection plate, molarity of the polymer solution, the temperature of the room and several others. These parameters must be met in order to create the optimal fiber length, diameter and density of the mat. Through our research, we have decided that the best approach to design a semi-permeable membrane capable of effectively filtering water would include using fibers of a small diameter that are densely packed. This approach will give the most effective water filtration properties. Nano-filtration can filter out particles as small as .001 micrometers (see below).

Source: http://www.dowwaterandprocess.com/products/uf/mfs.htm

The many contaminants found in water are of all different sizes and molecular compositions. We have chosen nano-filtration because it is effective at filtering a wide array of particles of different sizes. Polyethylene Oxide is being used to create the nano-fibrous mats in the hope that filtration of bacteria, macromolecules, pharmaceuticals, and other contaminants can be effectively filtered.

 Source: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1657971

The images above display scanning electron microscope (SEM) images of different PEO fibers. These fibers have different diameters and fiber densities which have an effect on the porosity of the mat.

If the weather holds up, we hope to begin spinning in the lab tomorrow. The problem is that humidity has a large effect on the electrospinning process. High humidity levels will make it difficult to spin the PEO in water. Desirable humidity is below 50% and above 70%, fibers will not effectively form.

Design Proposal: An Insight on Plans to Come

As we roll into week 3, the overall goal for this project has become clear. The electrospun nano-fibers will be used for water filtration. Current ways of filtration such as Philadelphia water treatment and Brita filters were analyzed to give a general understanding how existing water filtration occurs.

Design constraints such as availability of polymers, lab hours, and quality of equipment were determined. Lab hours will be scheduled by the end of this weeks lab section. A detailed project schedule was also created and can be view in the Project Overview tab. At this time, an exact budget cannot be determined due to the fact that most of the materials needed will already be provided to us. If we determine it is necessary to purchase additional supplies, they will be handled immediately and recorded in the projected budget.

Formation of a group

In week one of the Engineering Design Lab project a group consisting of Richard Dambra, Abraham Giorgis, Carl Huebner, Kyle Miller, and Gregory Muradyan was formed. Together we decided upon using electrospun chitosan polymer membranes for filtration purposes. Richard was assigned as the project coordinator, Abraham is in charge of data analysis, Carl is the technology coordinator, Kyle will be leading the research, and Gregory will be assisting in research as well as being head of experimental procedures.