It took Mullin five years and five prototypes to shrink the components. His first version, completed in 2003, included a circuit board tethered to a laptop that processed incoming sensor data. Now—in part because of a low-energy, light detecting sensor that he developed—the battery and all the necessary electronics are compact enough to fit within standard sunglass frames. Still, the glasses aren't quite market-ready; while testing the most recent prototype, the LCD lenses occasionally malfunctioned. "After they were in the glasses, some of the rows [of pixels] stopped working," Mullin says. To prevent such problems, he plans to strengthen the electrical connections that allow commands to be sent from the microcontroller to the lenses. In addition, he's developing flexible plastic-based LCDs (in lieu of glass), so the finished product will be lighter and shatterproof enough for commercial sale.