“Computers and Eggs?”
Organic field-effect transistor (OFET) fabrication using chicken albumen as a gate dielectric. The albumen is spin-coated onto an indium tin oxide (ITO) substrate and heated. Carbon materials and gold (Au) are deposited under vacuum. S: Source. D: Drain.
By Scott Hamilton
For the record, I would never have imagined such a combination would be a good thing. What do eggs and computers have to do with each other at all? However, I found out this week that there has been ongoing research for more than a decade to utilize the albumin from chicken eggs to create organic semiconductors. The research started off in 2011 when a set of researchers in Taiwan spin-coated and lightly baked egg whites as a dielectric material in a transistor gate. So I guess before any of this causes confusion, you need to have a basic understanding of transistors.
A transistor is an electrical component primarily used in digital electronics to act as an on/off type switch. In the case of the egg-transistor, they were building what is referred to as an organic field-effect transistor (OFET). The basic concept behind a transistor is that you separate two semiconductor materials with a dielectric semi-conductor material. You can think of the dielectric as a type of material that will not conduct electricity itself, but requires electrons from another source to allow it to conduct. In a transistor we add an extra electrical lead to the “gate” dielectric which feeds it electrons from another part of the circuit. When the gate fills with electrons, it conducts electricity, basically turning on the switch between the collector and emitter of the transistor.
Transistors are used for creating logical circuits that perform extremely basic logical operations on a computer. These logical operations combine to do more complex mathematical functions like multiplication, addition and subtraction, but if you can do basic logical comparisons you can do any mathematical function. As a result, if you can use an organic material like egg-whites to build OFETs, you can use the OFETs to build logic functions and eventually you can build an entirely organic computer.
In 2015 Korean scientists built upon the original research out of Taiwan and built the first Egg Bio-Memristor, which is a device designed to both perform a mathematical operation and store the result. Their prototype was able to remain stable for over 500 cycles and was declared as the first step towards denser memristor arrays. These arrays are the building blocks for future computing systems. It was only very shortly after these results that they began to combine nanoparticle composites into the egg whites to introduce completely new functionality.
The Royal Society of Chemistry published a paper by Dr. Jing Geng in 2015 titled “Freestanding eggshell membrane-based electrodes for high-performance supercapacitors and oxygen evolution reaction.” In the paper Geng outlines the detailed methods of creating useful organic electronic components out of common waste materials. He found that eggshell membranes offer a nearly perfect surface for building nanowires and carbon nanotubes. They have a unique, three-dimensional, grid-like fibrous structure and abundant macropores, allowing them to be utilized to grow carbon nanotubes, which are highly-effective compounds for building super-capacitors. The egg-based super-capacitors outperformed their silicon equivalents, but they have not made it yet to mainstream production.
In November 2023, Thomas Pucher and a team of scientists published a paper about their research with albumin (egg-whites) in which they provide details on how they utilized the semiconductor properties of albumin to create an insulation layer in semiconductors, normally done with silicon dioxide, and according to their studies, they found the albumin layer to be superior to the silicon used today. They found they were able to make excellent photo-transistors. These are transistors that convert UV spectrum light to electrons, allowing the flow of power across the transistor to increase as it is exposed to more light.
I know it is probably not very interesting to get into the details of their research and probably more interesting to know what the planned use for such technology might be. The end goal of this research is to allow for medical device implants to be made out of organic material, in hopes that it will cleanly break down in our bodies without side effects as the device becomes no longer useful. Think about things like an injection that contains a micro-camera for looking inside the blood stream, which does not need to be recovered because it dissolves in hours or days. Not only that, but I think it is really cool that we can use organic materials which are produced every day through natural processes to eventually build complex computing systems. It is something I am interested in learning much more about.
Until next week stay safe and learn something new.
Scott Hamilton is an Expert in Emerging Technologies at ATOS and can be reached with questions and comments via email to shamilton@techshepherd.org or through his website at https://www.techshepherd.org.
