We planned to design a reactor system that is suitable to investigate the electrochemical behaviour in bioprocesses. That includes the possibility to characterize mediators and different electrode materials on the one hand and the electron uptake into the cells on the other.
During our research we discovered the H-cell reactor that seemed to meet with our needs. (Park et al., 1999)
We approached two different concepts to realize the reactor construction. One of our H-cell reactors was constructed with the possibilities given to us by the facillities of our university. We instructed the glass workshop to modify two glass bottles by adding a glass-flange. Besides that the technical workshop build the lids from stainless steel. This approach had the advantage that we could influenze the design and had to make precise design drawings especially for the connections in the lids.
The second H-cell reactor was a commercially available system by Adams & Chittenden scientific glass. The commercial system had a smaller volume and the benefit

Figure 1: H-cell reactor set up. You can see the anode- and cathode- compartments which are connected by a glass flange. The water-heating connection, fumigation and the wiring of the needed electrodes. It is a three electrode set up with working- (WE) und reference- electrode (RE) in the cathode space and a counter electrode (CE) in the anode space.

Cyclic voltammetry - mediator characterization

During our experiments we used a Ag/AgCl reference electrode for measuring the working electrode potential. The counter electrode, which completes the cell circuit, was made from platinum wire. Platinum has the advantage that it is an inert conducter.

Cultivation - constant voltage

The first experiments in the H-cell reactor were performed under constant direct voltage. These experiments were performed to test the set up. We investigated if E. coli was able to grow in the needed voltage range and if the different mediators influence the cells if a small electric current is applied.

Chronoamperometry - current consumption

Figure 2: Overlay of the chronoamperometric measurements from cultivation A B and C.

Flow Cell