Crain's Eureka Index ranks Chicago's most innovative firms

Midtronics Inc. came up with a way for a mechanic to safely work on a car battery without getting zapped. That's not a problem with garden-variety, 12-volt batteries, but it's a much bigger challenge with the 400-volt monsters that power hybrids and electric vehicles.

Cummins Allison Corp. invented a machine that can take pictures of currency and checks even as they fly past in a blur, and do it in a fraction of the time of older equipment.

Gogo Inc. figured out how to maintain a cellphone signal when the user is in an airplane traveling 600 mph between towers.

Who says all the innovation happens in Silicon Valley?

Those three companies finished at the top of Crain's Eureka Index, our annual look at the most innovative businesses in Chicago and across the state. The rankings are based on an exclusive analysis of patents by Ocean Tomo LLC, a Chicago-based merchant bank that specializes in evaluating intellectual property.