Motivation

The broad goal of our project was to engineer s. Odenisis to produce a detectable change in electric current in response to some environmental stimulus. In order to observe such a reaction, our first task was to design an environment capable of housing bacteria and measuring current production.

Solution - Microbial Fuel Cells

Background

Microbial fuel cells (MFCs) are devices that use bacteria as the catalysts to oxidize organic and inorganic matter and generate current <ref></ref>. The principle behind these devices is to physically separate an oxidation reaction from a reduction reaction while providing a path for electrons to travel between them.

Context

Design Goal

Functional description

The final product is a complete system capable of introducing separate strains of bacteria to multiple different environments while simultaneously measuring and recording current readings from each. The experimenter specifies the number of bacteria/environment combinations to be run, as well as the initial conditions for each. Data collection and storage is automated, with a computer displaying live current readings and graphing historical current levels. The experimenter can change the conditions of any fuel cell throughout the course of the experiment without affecting other fuel cells. The fuel cells themselves are stand-alone, capable of being treated as individual circuit components.

Specifications

• automated

Some experiments can last several days. Measurements must be automated to allow for overnight observation.

• anaerobic/aerobic

s. Odenisis only oxidizes substrates in anaerobic environments. The chamber housing the bacteria must be oxygen free and airtight.

• sterile

Fuel cells must be capable of being sterilized to prevent contamination

• reproducible

Individual fuel cells must be similar enough to produce consistent results.

• accessible

Experimenters must have access to the bacterial environment.

Approach

Decomposition into components

Construction of the system was broken down into three distinct parts. The most important components were the fuel cells themselves. Once these devices were built, a measurement system was constructed to sample current readings from each simultaneously. Software was developed to orchestrate these readings, recording and displaying them in real time.

Component descriptions and approaches

Fuel Cells

Measurement

Software