The Eve of Bioelectronic Engineering
The electronics industry has been utilizing metal and glass for the past 200 years. Semiconductors, largely made of silicon, have been around for 60 years. With the recent production of 14nm transistors, the industry has finally recognized that the trend in transistor size is not sustainable and the scaling of transistors will slow down until it becomes more commercially viable. Thus, scientists have been exploring many different options for increasing computational power including the use of quantum computers and light to process information.
The valve was common in electronics until transistors became commercially available. Image courtesy of Fred von Lohmann [CC BY 2.0]
While there are many scientists who believe that the future in electronics lies in materials that exhibit strong quantum properties or superconductive abilities, there are others who believe that the answer may lie within us. Literally!
The idea is that living organisms, themselves, could help with producing sensors and providing computational power. Scientists have already demonstrated how chemicals and enzymes can compute digital logic while DNA can be used to perform computation including the ability to play tic-tac-toe. But most of these ideas are in the very early stages of research and development. Real working devices are few and far between and can only exist in controlled environments such as those found in laboratories. In other words, most of these ideas are far from being introduced into the consumer world.
However, the US Army has taken a special interest in the use of bacteria in electronics and believes that bacteria could be used in as little as 10 years.
Microbes in the Generation of Electricity
Microbes have already been the subject of research when it comes to electricity.
One example is the generation of electricity using microbes in the form of a microbial fuel cell. Using microbes and a few materials (including an expensive proton exchange membrane), electricity can be generated from bacteria that produce hydrogen ions as a byproduct which can, in turn, be used to create a voltage gradient (and hence provide electrical power). While these cells individually produce less than a volt (0.6V to 0.3V), their source of electricity is organic matter (waste food, fallen leaves, etc.) which makes them ideal for converting waste to electricity.
The waste produced by such cells is not radioactive, poisonous, or even harmful but is instead just decayed organic matter which can be used in fertilizers. Even the hydrogen gas byproduct can be further used to generate electricity for powering vehicles.
Microbes can be used to generate electricity. Image courtesy of MFCGuy2010 (own work) [CC BY-SA 3.0]
It is, therefore, no surprise that the US Army is considering integrating bacteria into electronics and believes that it will become mainstream in a decade.
How to Train Your Bacteria
There are many methods for utilizing living organisms in electronic systems such as genetic programming and the use of symbiotic relationships between different organisms. Dr. Bryn Adams of the Army Research Lab (ARL) has many ideas and hopes for organisms in electronics including the use of photo-syntheses to produce electricity. According to her, the use of synthetic biology could allow engineers to program "genes" into devices to dictate specific functions, attributes, or reactions to stimuli.
In order to get bacteria to perform a specific task or exhibit a property (such as glow in the dark), it has to be engineered using DNA splicing techniques that can insert and remove specific genes. However, since the mid-2000s, new gene programming systems have been developed which allow for the creation of a custom DNA sequence. It is these systems that may allow for entire organisms to be designed from scratch to perform the needed operations such as producing electricity, detecting stimuli, and even perform calculations.
One clever example of bioelectronics is the data recording capability of genetically engineered bacteria using a programming language called Cello. Essentially, in the course of the bacteria's life, it records environmental conditions directly into DNA which can then be read out through sequencing.
Over the course of her research, Adams has connected with the Voigt Lab at MIT and fellow military researcher Dr. Sarah Glaven at the US Naval Research Laboratory as they all work towards bringing synthetic biology into the field.
Read Adams's editorial entry to the Synthetic Biology journal here to learn more about her views on how synthetic biology technology could change the world.
The Future for Bacteria
While bacteria will not be in consumer electronics for quite some time, it's possible that they could be integrated into actuators and sensors soon.
The concept of living organisms in electronics opens up the possibility of self-healing organic devices which can monitor the environment and repair damage that may be inflicted (not unlike healing in living organisms). However, there are many complications that come along with this technology, including the danger of accidentally creating dangerous bacterial strains that could be harmful to the people exposed to them.
MRSA can be fatal if caught. Image courtesy of the NIAID
Thankfully, our immune systems are very good at fighting against bacteria due to the millions of years of evolution—but engineered bacteria may be something that our bodies have never had any experience with. On top of that, bacteria have a nasty tendency to evolve via mutations which change their characteristics enough to be unpredictable.
Devices containing synthetic organisms may need to be kept in a sealed environment or pass a certain amount of experimentation as to prevent such problems. Would it mean that producers of such synthetic organisms will be obligated to produce antibiotics against such bacteria in the event that the engineering organism causes an outbreak? How will such an industry be regulated?
It will be interesting to see how bacteria will play a role in engineering in the years to come.