A Collection of Articles


35 Innovators Under 35


Meet seven people who hope to turn innovations into ­disruptive businesses.

Christine Ho, 33

Imprint Energy

Her startup is commercializing thin, flexible, printable batteries that she developed at UC Berkeley.

You say we’ll want Imprint Energy’s zinc batteries for wearable electronics, health-monitoring patches, and small sensors. Why can’t we put existing batteries into such devices?

A lot of these batteries need a lot of plastic housing or metal housing. They need protective circuitry. Because you’re doing everything you can to tame a very, very wild and reactive system. What’s interesting about Imprint’s approach is we’re using an inherently more stable chemistry that doesn’t need that hermetic sealing. [That results in] the packaging being much more simplistic and thinner. What’s nice about zinc batteries is the materials are really cost-effective and easy to acquire. They’re also nontoxic.

Ho says devices using Imprint Energy’s batteries could appear by 2018. The company is working with manufacturers ­to screen-print batteries on sheets like this one.

Why isn’t zinc already widely used to power electronics?

There’s usually a very nasty corrosive electrolyte used [with it]. Especially for on-body applications, you don’t want to put in something nasty like that. The other thing is, zinc is not traditionally a rechargeable system.

How did you get around those issues? 

Batteries are stacked; they look like a stacked sandwich. The middle layer, like the jelly in the jelly sandwich, is called the electrolyte. What I realized was that if we eliminated that and replaced it with something that is stable with the zinc system and rechargeable, we could open up a whole new market space. I looked at lots of different materials, literally throwing everything in a bucket and hoping that it worked. We started to get some really interesting results with one of these material sets we were looking at. We could basically take this material and cast it into a solid film. So you could cut it, you could stretch it and whatnot, but inside it had ions that moved.

—Rachel Metz