A surface mountable glucose fuel cell for medical implants

We present an enzymeless, surface mountable glucose fuel cell based on abiotic catalysts. The device is intended as an energy harvesting implantable power supply for low power medical implants and sensors. After 50 days of operation in physiological glucose solution the fuel cell exhibited a stable performance of 1.1 muW/cm2. The demonstrated lifetime of our glucose fuel cell therefore already exceeds the maximum lifetime reported for devices based on enzymatic catalysts. This renders the concept a promising approach for the development of autonomous and sustainable power supply systems for long- term medical implants

Asymmetric bipolar membrane: A tool to improve product purity

Bipolar membranes (BPMs) are catalytic membranes for electro-membrane processes splitting water into protons and hydroxyl ions. To improve selectivity and current efficiency of BPMs, we prepare new asymmetric BPMs with reduced salt leakages. The flux of salt ions across a BPM is determined by the co-ion transport across the respective layer of the membrane. BPM asymmetry can be used to decrease the co-ion fluxes through the membrane and shows that the change of the layer thickness and charge density of the corresponding ion exchange layer determines the co-ion flux. The modification of a commercial BP-1 with a thin additional cation exchange layer on the cationic side results in a 47% lower salt leakage. Thicker layers result in water diffusion limitations. In order to avoid water diffusion limitations we prepared tailor made BPMs with thin anion exchange layers, to increase the water flux into the membrane. Therefore a BPM could be prepared with a thick cation exchange layer showing a 62% decreased salt ion leakage through the cationic side of the membrane

Tailoring the interface layer of the bipolar membrane

This work investigates various parameters affecting the water splitting of bipolar ion-exchange membranes. We show that the amount of functional groups and the water content of the interface layer have a strong influence on the bipolar membrane resistance. Use of anion exchange layers containing quaternary ammonium groups instead of bicyclic amines results in bipolar membranes with low electrical resistance. The influence of an iron and pyridine based catalyst in the bipolar membrane junction is investigated as well. We show that the pyridine based interface layer is a good tool to prepare tailor made bipolar membranes containing anion exchange layers with high base stability without having water splitting catalytic functional groups