by Hannah Brown

Biomimetics is the principle of using processes found in the biological world and adapting them for specific, technological human needs. An example of this is nanotechnology. Inspired by the ways viruses operate, researchers have developed miniscule drugs that can target and treat specifically cancerous cells. We also use nature inspired products every day. Velcro, for example, was developed after a Swiss engineer studied the construction of tiny plant barbs that so easily stick to clothing. (science.com)

A new and exciting type of biomimetics comes in the form of the “bionic leaf.” Reported on in a study released in the end of 2014 by Proceedings of the National Academy of Sciences, the bionic leaf was developed starting in 2009 by researchers now at Harvard. The idea is a form of reverse combustion, where CO₂ is turned back into fuel, and abiotic and biotic catalysts are used in conjunction to successfully transform energy into fuel.

It works like this: water is split using a catalyst made of earth metals, cobalt-phosphate, to make hydrogen. As hyrodrogen is rarely used as a transportation fuel or for electricity, a specifically engineered form of bacterium Ralstonia eutropha is used to convert the CO₂, H₂ and O₂ made from the water-splitting into isoproponal, a liquid form of energy.

Essentially, this bioreactor, powered by photovoltaic solar cells in this case, feeds starved microbes hydrogen from the water that has been split by the specific catalysis.

As microbes can turn energy into other molecules, the researchers introduced the specially engineered soil bacteria, R. eutropha, that uses the hydrogen as energy to build molecules out of carbon. From this process, isopropanol is created. While isopropanol is a form of liquid fuel, it is not as commonly used as others. However, the researchers believe that with adjustments and further research, the bionic leaf could produce other fuel, or pharmaceuticals, among other things, with just the combination of sunlight and CO₂. (salon.com)

As stated in the original study “liquid solar fuel derived from CO₂ holds promise as both a storage mechanism for solar energy, and as a renewable, carbon-neutral, and infrastructure-compatible energy supply.” (Torella, et. al. 2014).

This bionic leaf is an intriguing form of biomimicry. As it combines non-living and living processes, and in the end creates liquid fuels from solar energy (a sort of electrofuel), it shows the variety of possibilities in the junction of biological, electrical and chemical engineering fields.

Joseph P. Torella, Christopher J. Gagliardi, Janice S. Chen, D. Kwabena Bediako, Brendan Colón, Jeffery C. Way, Pamela A. Silver, and Daniel G. Nocera. Efficient solar-to-fuels production from a hybrid microbial–water-splitting catalyst system. PNAS 2015 ; published ahead of print February 9, 2015, doi:10.1073/pnas.1424872112

Biello, David. “’We think we can do better than plants’: New ‘bionic leaf’ makes fuel from sunlight.” Salon.com. February 15, 2015

Strickland, Jonathan. “Top 5 Ways Nature Has Inspired Technology.” Science.howstuffworks.com. April, 23, 2009.