Final Design

Final Genetically Modified Mosquito Incubator Design

The final design of the Mosquito Control Box includes three major components: the bowl, the lid, and the hanging mechanism. The bowl features a tapered rectangle geometry that holds one liter of water with an overall depth of 4”. The lid attaches to the bowl with a snap fit mechanism and has three ¼” holes that act as a passageway for the male mosquitoes to exit the container once they have developed. The hanging mechanism allows the container to be used in various locations and keeps small animals from being able to open or damage the container.

Lid

The lid has two rectangular indentations in each side that snap over the lip of the bowl and ensure it is tightly covered and not easy to remove with wind or animals it may encounter. It is fabricated out of 1 mm polystyrene (material selection discussed in Appendix D1 of Report). There are three 0.635 mm (¼”) holes drilled in the top for the male mosquitoes to escape — the size and number of holes was recommended by our sponsors after testing in the lab.

Bowl

The final design for the bowl that will incubate the mosquitoes is rectangular shaped and made from 0.3175 mm (⅛”) black HDPE. The material choice is further discussed in Appendix D1 but the sponsors stressed the importance of a dark, opaque container as mosquitoes grow better in dark environments and possibly making it easier for the males to escape if they are drawn towards the sunlight coming in through the holes in the lid. There is a 1 cm lip around the edge that the lid will snap onto and there are no sharp corners on the bowl to aid in the vacuum forming process and reduce stress concentrations.

Hanging Ability

Our sponsor expressed interest in providing customers a way to hang a bowl, such as from a tree or against a house, to better ensure it is not disturbed by animals and save space. Our final solution was to attach invisible hanging wire to the middle of each side of the bowl and tie them together at the top. The wire is low cost, very strong, and would not take up too much space when shipping.

Performance

The key performance metrics tested were the ability of the mosquitoes to exit the container through the holes in the lid and the hanging mechanism under the weight of the container filled with water. 

From preliminary prototype lab testing, in which 24 pupae were observed in a clear bowl and lid prototype, 71% emerged to adulthood while 17.6% exited the bowl through the holes in the lid. From this initial testing, it was concluded that a darker lid will create more contrast with light entering the holes in the lid, which will act as a physical cue that is critical for adult escape. Preliminary testing also led to the conclusion that there must be a minimum of 3 holes in the lid. As shown in Figure 2, the final box prototype was tested in Synvect’s lab with 100 male pupae. The final box design will continue to be tested as Synvect progresses in their development of their ngSIT technology. 

Manufacturing Requirements and Recommendations

Due to the nature and scope of this design project there were several changes and material selections that we would recommend implementing tor future design iterations and scaling up for manufacturing. we recommend mass production to be conducted with ⅛” Marineboard as it is already UV stabilized and removes the need for the UV stabilizing spray used in the scope of this class. 

 Additionally, there are several different choices for mass manufacturing options. If the Vacuum forming used in this project is to be continued we would recommend a more robust, automatic vacuum former, such as a Formech TF1050. However, with box numbers potentially reaching tens of thousands,  the up front cost of a mold for injection molding would return on its investment and potentially be more cost effective in the long run. Additionally, if Injection Molding is used in mass manufacturing it would be possible for some small changes in the design for more desirable shape and functionality. The materials would have to change for ease of injection.

For the creation of a 2 liter bowl, we would advise extending the length and width of the box to create more surface area and maintain the parameters on the water and air levels in the box. For consistency in cutting the lip on the bowl and lid, we would recommend either manufacturing a die or stamp to use in tandem with the automated Formech for consistent fits.