Extracting Energy from Cockroaches

The movement to extract new biofuels from insects has been attracting attention for several years. In particular, the use of cockroaches, which have a strong image of being a pest, has been proposed as an eco-friendly way to generate electricity and a new future where organisms and machines coexist. This method of power generation using insects is being researched by Professor Keisuke Morishima of the Department of Mechanical Engineering, Graduate School of Engineering, Osaka University.

Structure

The basic principle of the biofuel cell, which uses the circulation of insect body fluids, is that by pouring insect body fluids into a device attached to the body, a chemical reaction occurs that generates weak electricity.

Specifically, two holes are drilled in the insect's back and a device is attached to it so that body fluids can circulate between the device and the insect. This enables the insect to generate electricity while still alive. The insects' body fluids, not just cockroaches, are rich in trehalose, a sugar that is broken down into glucose. This glucose reacts chemically with the electrodes inside the device to generate electricity.

Contrivances

In order to make this mechanism work smoothly, enzymes are used to break down trehalose, ingenious ways to increase the surface area of the electrodes, and carbon electrodes are used. However, the amount of electricity generated by this is still very small. Therefore, the membrane in the device is important to increase its efficiency.

Body fluids contain many unwanted elements, such as impurities and proteins. Therefore, a membrane is needed to separate them. The efficiency of power generation and the durability of the device depend greatly on this membrane. It is believed that further efficiency improvements will be possible if the structure and enzymes of the electrodes are refined.

Applications

In research on the use of cockroaches as disaster robots, a fuel cell was attached to a cockroach, and 333 µW (microwatts) of power was generated. The power generation is still low, but theoretically, the cells can continue to generate power as long as the insects are alive. Research is continuing toward the realization of "Cyborg Insects".