A Micro-Fabricated Aluminum-Air Moving Biofluid Battery For Medical Wearables

We report a thin film wearable aluminum-air battery that utilizes the flow of a biological fluid (eye tear) as a moving electrolyte. When the eye blinks, the eye-tear fluid comes into contact with two metal electrodes, and it produces spontaneous redox reactions, which generate an electric current when connected to a load. In this paper, we demonstrate that a 5×5 mm
²
tear-activated Al-air battery is capable of providing maximum energy of 45 µJ per eye-blinking cycle. Furthermore, we investigate the effect of different air-breathing electrodes, including gold, platinum, and silver, on the battery's performance. Results demonstrate that the battery's maximum voltage and current outputs are 1 V and 220 µA while using Pt as the cathode. The moving biofluid Al-air battery with the Pt cathode charges up a 10 µF capacitor in 10 s. Furthermore, load line analysis shows a maximum deliverable load power density of 64 µW· cm
⁻²
for this device.