https://www.imtek.de/data/lehrstuehle/app/dokumente/publikationen/publpdf2008/kerzenmacher-energy-harvesting-by-implantable.pdf

Energy harvesting by implantable abiotically catalyzed glucose fuel cells

In experiments performed using graphite electrodes poised by a potentiostat (+200 mV versus Ag/AgCl) or in a microbial fuel cell (with oxygen as the electron acceptor), the Fe(III)-reducing organism Geothrix fermentans conserved energy to support growth by coupling the complete oxidation of acetate to reduction of a graphite electrode. Other organic compounds, such as lactate, malate, propionate, and succinate as well as components of peptone and yeast extract, were utilized for electricity production. However, electrical characteristics and the results of shuttling assays indicated that unlike previously described electrode-reducing microorganisms, G. fermentans produced a compound that promoted electrode reduction. This is the first report of complete oxidation of organic compounds linked to electrode reduction by an isolate outside of the Proteobacteria.

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Evidence for involvement of an electron shuttle in electricity generation by Geothrix fermentans.

The present invention relates to fuel cells. More particularly, it relates to a fuel cell which produces electricity from the anaerobic oxidation of hydroxylic compounds, e.g. alcohols and sugars, in the presence of a quinone.

Fuel cell using quinones to oxidize hydroxylic compounds

In developing implantable biofuel cells to generate higher power it is essential to prepare very thin and highly active electrodes in order to produce the required energy in as small a volume as possible. A method has been developed for glucose electrodes which enables us to produce firmly adhering active layers on very thin foils (up to 50 μn) of homogeneous alloys, containing platinum and a ferrous metal, by controlled anodic dissolution of the non-noble metal. Such electrodes are roughly 10 to 20 times more active than conventional glucose anodes. The activity is remarkably increased by the addition of tungsten and tantalum to the alloy. So far it has been possible to transfer 17 out of the 24 available electrons of the glucose molecule.

A special type of Raney-alloy catalyst used in compact biofuel cells

It has been demonstrated that a radio frequency magnetic field can be used to power implanted electronic circuitry for short range telemetry to replace batteries. A substantial reduction in implanted volume can be achieved by using only one RF tank circuit for receiving the RF power and transmitting the telemetered information. A single channel telemetry system of this type, using time sharing techniques, was developed and employed to transmit the ECG signal from Rhesus monkeys in primate chairs. The signal from the implant is received during the period when the RF powering radiation is interrupted. The ECG signal is carried by 20 , us pulse position modulated pulses, referred to the trailing edge of the RF powering pulse. satisfactory results have been obtained with this single frequency system. The concept and the design presented may be useful for short range, longterm implant telemetry systems.

Single Frequency RF Powered ECG Telemetry System

A biological fuel cell such as an oxygen/glucose cell has been considered to be an ideal power source for implantable cardiac pacemakers and similar devices. This study is mainly concerned with the development of a single oxygen/glucose cell, which can be implanted inside the body fluids with the simultaneous presence of oxidant and fuel(s). Present results ofin vitro experiments with a single oxygen/glucose cell consisting of a platinum black on platinum-mesh electrode (cathode) and a platinum black on porous-graphite electrode (anode) have shown that cell performance was markedly increased after glucose addition. Half-cell testings by means of a potentiostat coupled to a linear sweep generator also demonstrated that the anode current of a platinised graphite electrode after glucose was over 3 mA/cm2. It was also found that a steady and continuous power output of 20 μW/cm2 could be generated from the above oxygen/glucose cell. When the cell was testedin vivo in the rat. the continuous power output was steady at 3·3 μW/cm2. The present study also investigated the possibility of generating electricity from an oxygen concentration cell and an oxygen/hydrogen cell. It was concluded that a platinum black on porous graphite electrode offers promise as a specific electrode for glucose oxidation. An oxygen/hydrogen cell could also provide a long termin vivo power supply provided the Pd-H electrode is properly encapsulated. The significance of the present study in relation to the development of biological power sources is discussed, and the importance of fundamental investigation for the development of a specific electrode is emphasised.

B. Y. C. Wan

Papers

Some studies related to electricity generation from biological fuel cells and galvanic cells, in vitro and in vivo.