Our engineering design group set out to achieve a simple, affordable, convenient form of tactile currency for the United States. We discussed the possibility of Braille stamping, but after consulting with the American Council for the Blind, we turned our attention elsewhere; Braille stamping had been attempted previously and was determined to be an impractical solution because it would wear down over time and be indiscernible from any other denomination. In addition, we had concerns that Braille itself would be very difficult for new users to learn. It is difficult enough even for experienced readers to discern between the different denominations—a ten-dollar bill has eight dots while a twenty-dollar bill has nine dots. After discovering the difficulties and impracticalities that surround Braille stamping, we devised a clearer, more general form of identification: a bar system. This system was to be used with our second design- varying the thickness of the paper. This design was more cost effective than our third design, which involves weaving metal strips into standard issue bills. However, after extensive research, we had determined that varying the thickness was impractical as well; the raised ridges would suffer the same consequences as the Braille stamping; it too would wear off over time. Our third design involves strips that run vertically through the bill varying in position from one to two inches from the left of the face of the bill depending upon the denomination. It would have a varying number of bars placed on them to denote their value. For example, the one-dollar bill would have a metal strip interlaced in its layers one inch from the left side of the face that would have a raised, full bar indicating that the monetary value of the bill was one dollar. A five-dollar bill would have a strip one-and-a-half inches in and have two bars raised signifying its value. The ten, twenty, fifty and hundred bills would each have distinct positions with three, four, five, and six bars respectively.
The metal strip, in order to be the most durable and cost effective would need to be manufactured out of an aluminum alloy. This would allow it to survive the harsh conditions that dollar bills are put through. Aluminum can be rolled into very thin sheets, is malleable and cheap.
The metal stripping would be manufactured into rolls, which would then be inserting in the final stages of the paper making process. The stripping itself would have raised ridges on it, which would stick out of the paper. After the paper has gone through the drying process, precisely positioned welding heads would then melt the raised portion of the strip to create a lip over the paper; this would prevent the bill from wearing away from its exposed edge.
Because of our limitations, our prototypes could not appear as the true product would if it were to be produced in by the United States Bureau of Engraving and Printing. Since we were unable to insert a metal strip into the bill during the manufacturing process, we have placed the bars topically onto the bill. Weaving an aluminum bar with solder into the bill was unsuccessful. The paper would gather up in certain locations and the aluminum would not stick to the solder. We created three identical prototypes by gluing solder molded into the proper shape and thickness of one-dollar bills. These one-dollar bills appropriately reveal a single bar (Appendix 4). Our prototypes accurately depict the style of the bars for the denominations and the width of the metal that would be placed inside the currency. The bars are only tacitly recognizable on the face side of the dollar. This was done so that the visually impaired will be able to insert the bill correctly, face up, into vending machines.
Problems that needed to be resolved in our final design were: ease of detection by persons with little or no vision, vending machine compatibility, durability, and cost effectiveness. With our current and final design, we have achieved all of these things.