Flexible and transparent gastric battery: energy harvesting from gastric acid for endoscopy application.

In this paper, we present the potential to harvest energy directly from the digestive system for powering a future wireless endoscopy capsule. A microfabricated electrochemical cell on flexible parylene film is proposed as a gastric battery. This electrochemical cell uses gastric juice as a source of unlimited electrolyte. Planar fabricated zinc [Zn] and palladium [Pd] electrodes serve as anode and cathode respectively. Due to planar geometry, no separator is needed. Moreover the annular structure of the electrodes provides lower distance between cathode and anode reducing the internal resistance. Both electrodes are biocompatible and parylene provides flexibility to the system. For a surface area of 15 mm(2), 1.25 mW is generated which is sufficient for most implantable endoscopy applications. Open circuit output voltage of this battery is 0.75 V. Since this gastric battery does not require any external electrolyte, it has low intrinsic weight, and since it is flexible and is made of biocompatible materials, it offers a promising solution for power in implantable applications.