Alternative Design Methods

 UNDER CONSTRUCTION

Alternative methods research is an integral part of any design process. It is important to investigate other possible approach methods to the solution of a problem. Alternatives often also give insight into parameters that must be taken into account for the design. Alternative approaches often involve pros and cons. Some of the alternative methods that have been researched are documented below in order to offer insight to other solutions, as well as suggestions for further research beyond the 10 week project.

Layering:

Layering is the method of adding different mediums on top of each that can provide for different responsibilities. A good example of this would be a thin coated top layer, most likely chitosan, that lies above the main Poly-ethylene oxide mat. In addition to these top two layers, a structural bottom layer could also be incorporated into the design. Layering has been shown to increase the mats resistance to bio fouling while involving multiple polymers to aid with the water filtration.

Figure A: A visual of how layering works

Coating:

There are several alternative methods that the group has begun looking into as possible ways that we could improve our design. One of the alternatives currently being examined is coating our Poly-ethylene Oxide (PEO) polymer with chitosan. By coating the top layer with a thin film of chitosan another dimension would be added to the mat, ultimately filtering out more unwanted substances. Chitosan is a hydrophilic biopolymer that is insoluble in neutral pH conditions [7]. Because of these properties, chitosan makes for the perfect polymer to coat our PEO with. Unfortunately there is no chitosan at the groups disposal, but if we were to take the project further than freshman design chitosan would end up being a major aspect in our electrospun mats.

UV-Treatment:

In addition to layering and coating the polymers, an issue with the PEO solution must be resolved in order to further the filtration design. The PEO solution is formed with water, thus it can also be dissolved in water. This is a major problem seeing how the goal of the groups engineering project is to engineer a method of water filtration. One solution to this problem would be using Ultraviolet (UV) radiation to harden the mat. UV irradiation causes a formation of radicals in macro-chains which is followed by a breakdown of chemical bonds [8]. UV- treatment has also proven to rearrange the macro molecular molecules of PEO. UV- treatment of PEO also acts as an etching agent that removes simple organic compounds enriched in the surface layer by means of evaporation. Research has shown that PEO should not absorb UV light at wavelengths longer than 200 nm, because this will excite certain macromolecules which can pose as a problem because excited macromolecules have different properties than those that are not excited [9].

Rotating Collector:

Another alternative that we are currently looking into is electrospinning a mat on a grid. The system would involve a syringe setup facing a rotating aluminum sheet. As the surface rotates and the fibers make connection with the aluminum and the grid is formed. This method has been proven to create a much more uniform grid like mat. The benefits of having a grid like mat would be would be more efficient filtration due to the uniform structure as opposed to the random fiber placement that results from the original electrospinning system.

Figure B: Rotating collection plate

 Below is a video that demonstrates how a rotating collector works.