Most scientists come up with design ideas after hours of countless brainstorming and meetings. But Yuan Yang, an assistant professor of material science and engineering at Columbia University, came up with with his big idea during a flash of inspiration during a workout session at the gym.

The result is the design for an extremely flexible and energy-dense lithium-ion battery that is shaped like the human spine. The result is a battery that could finally make portable chargers a practical reality — even allowing people to walk around with belts that double as batteries.

“When I was thinking about a battery design while doing sit ups, I started thinking about how I was using my spine to flatten my body,” Yang tells Inverse. “I realized that that our spine is flexible because it has both hard and soft sediments. That inspired the idea.”

Yang and his team’s design, which was published today in the peer-review journal Advanced Materials uses this novel design to solve the energy density issue that has bedeviled other flexible battery designs. Whatever advantages these earlier batteries had, they were overshadowed by the fact that they could not store a lot of energy.

This spine-shaped power source takes the traditional design for lithium-ion batteries and flips it vertically. The researchers cut long strips of the positively and negatively charged components in batteries, as well the element that separates them— known as the anode, cathode, and separator respectively — and wrapped them around a vertebrae structure. This vine-like design allows for robust energy density, just like your standard lithium-ion battery, and a large range of motion.

Yang sees a wide range of potential use for his team’s design. He says there should be a big market for improving consumer tech and developing more effective portable chargers. His design could replace the straps on smartwatches to make them even thinner and make charging your phone on the go easier than ever.

“Another possible scenario is to replace belts for trousers,” he said. “This way you if you need to charge your iPhone at any time you can just put it onto your belt which could be combined with wireless charging technology.”

Yang’s team has only developed a prototype for the sake of testing it for their design, but they are in talks with investors about making it commercially available. He said that if all goes well his team could possibly have something for consumers to try out in roughly three years.

Say goodbye to carrying around those bulky portable phone chargers in the near future.