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SunSac - product redesign

Project: SunSac
Project team: Christina Gambino, Nicholas Kirsch, and Alicia Lin
Class: PDI Studio I (Fall 2007)
Awards: Rensselaer Polytechnic Institute's "Change the World Challenge" Competition $1000 prize. Fall 2007. link to article

Objective: Improve the design of one of the products on display in the Cooper-Hewitt exhibit "Design for the Other 90%" Propose an improved design in a presentation structured as a report to a funding agency "selling" your work and justifying your request for funding to get the improved design into the hands of those who need it. It should include structured criticism of editing designs, an "elevator pitch" explaining how users' lives will be better after using your product, and drawings sufficiently detailed that someone else could build your design.

Abstract: Safe drinking water is a basic need, but for 1.2 billion people worldwide, this need is not being met. In Third World countries and developing areas, the people are forced to rely on contaminated water, which contains viruses that cause about 14,000 deaths per day. The process of solar water purification involves converting solar radiation into thermal energy to deactivate and kill disease-causing microorganisms. For the SunSac, we aimed to develop a simple water purification system that would be affordable to families (averge size of six) that survive on less than $2 a day. Solar water purification is ideal for this situation because it implements a free source of energy and requires a few inexpensive materials, while being effectively killing the dangerous bacteria in the water.

SunSac - project details

I was not able to make the trip to the Design for the Other 90% exhibit in New York City, so I did my research from the book and online exhibit. Three exhibits that caught my eye were the WorldBike prototype, the Q-Drum, and the AquaStar Plus! and Flow Through. All three were good ideas and innovations, but I felt that they could all be improved to be even more efficient and inexpensive. Our group chose to focus on redesigning the AquaStar Plus for our project. We realized that while the bottle was very effective, it was not able to hold a lot of water and cost too much for an impoverished user. We looked into different ways to build a product that was equally effective in killing germs but more efficient and went through many prototypes before we realized that implementing a UV-C light made the entire unit too costly. We stripped the UV-C light from the project and starting looking into solar ovens, filters, and solar water pasteurization. We found that pasteurization was the most effective, and then designed a prototype for the SunSac. Afterwards, we looked into the cheapest materials that would still do the job and continuted cutting down the cost until we ended up with our final design.

SunSac - final product

Our final product is essentially a heat sealed bag with a bottom layer of black polyethylene plastic and a top layer of clear polyethylene plastic with dimentions 50.8cm x 74.8cm x 3.0cm - a final volume of 11.4 liters. We chose this volume because the average family size in Africa is six, and each person requires 64 ounces of water per day. Our product has the capability to purify enough water for an entire family for one day. At one end of the bag will be a plastic nozzle about 1 inch in diameter which serves to fill and empty the bag. The bottom layer will have a small, clear pouch heat-sealed onto it with the interior filled with opaque candelilla wax that serves as a thermometer. As the entire process takes about eight minutes at 65C, we needed to implement a way for the user to know when to start keeping track of time. The solution to this was candelilla wax, as it has a melting point of 65C and turns clear when it melts. The current estimate for the entire unit is about $1.96, a cost that is sure to go down the the product is mass produced.