A California startup is developing flexible, rechargeable batteries that can be printed cheaply on commonly used industrial screen printers. Imprint Energy, of Alameda, California, has been testing its ultrathin zinc-polymer batteries in wrist-worn devices and hopes to sell them to manufacturers of wearable electronics, medical devices, smart labels, and environmental sensors.

The company's approach is meant to make the batteries safe for on-body applications, while their small size and flexibility will allow for product designs that would have been impossible with bulkier lithium-based batteries. Even in small formats, the batteries can deliver enough current for low-power wireless communications sensors, distinguishing them from other types of thin batteries.