Powering Electronic Devices from Salt Gradients in AA Battery-Sized Stacks of Hydrogel-Infused Paper

Abstract

Strongly electric fish use gradients of ions within their bodies to generate stunning external electrical discharges; the most powerful of these organisms, the Atlantic torpedo ray, can produce pulses of over 1 kW from its electric organs. Despite extensive study of this phenomenon in nature, the development of artificial power generation schemes based on ion gradients for portable, wearable, or implantable human use has remained out of reach. Previously, inspired by the electric eel, we developed an artificial electric organ that generated electricity from ion gradients within stacked hydrogels and, like the eel, was optimized to deliver large voltages that exceeded 100 V. Due to its high internal resistance, the current of this power source was, however, too low to power standard electronics. Here we introduce an artificial electric organ that takes inspiration from the unique morphologies of torpedo rays for maximal current output. This power source uses a hybrid material of hydrogel-infused paper to create, organize, and reconfigure stacks of thin, arbitrarily large gel films both in series and in parallel. The resulting increase in electrical power by almost two orders of magnitude compared to the original eel-inspired design makes it possible to power electronic devices and establishes that biology's mechanism of generating significant electrical power can now be realized from benign and soft materials in a portable size.