The prototype sunglasses use polymer films sandwiched between layers of glass. A switch on the sunglass frame sends a small current from a battery to the polymer in each lens, which makes the lens a darkened color. Another switch of current turns the lens back to transparent. It can stay that way for up to 30 days without being switched again.

The prototype only changes from one color to transparent; however, future generations of color-changing sunglasses will be able to change to various colors. The amount of color possible will depend on the chemical formula of the polymer and on the electrical potential applied by the circuit. This ability to change various colors will be possible with multiple sandwiched polymer films.

The Web page for the Center for Intelligent Materials and Systems is: http://depts.washington.edu/cims/.

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