The search for low-cost sustainable materials for electronic goods is taking researchers into some strange places, and now a team of scientists from National Cheng Kung University in Taiwan has followed a trail that leads straight to the barnyard. The team has successfully demonstrated that plain, unmodified egg white – aka albumen – can function effectively as an insulating material in an emerging class of electronic switches called organic field-effect transistors.
Organic transistors and electronics
Field-effect transistors are the “main logic units” of daily life in our electronic-based society. From their invention in the 1940’s until recently, they have been made with inorganic materials, primarily silicon. The addition of organic materials to the mix offers the potential for a significant reduction in manufacturing costs, since they can be sprayed over a large area onto a lightweight, flexible base.
A rough road to organic transistors
That sounds great in theory, but in practice using organic materials is not all that simple, as the Cheng Kung team points out:
“Biomaterials have many advantages for use in organic, carbon-based electronics and have garnered considerable attention in recent years. Not only are they biodegradable and biocompatible, but they also tend to be environmentally friendly and do not require chemical synthesis. They have the potential to cut the cost of organic electronics and to simplify manufacturing processes…However, the materials are not always easy to handle and can require many extraction steps.”
Smoothing the way with egg white
The researchers’ key finding was that egg white in its natural state could perform as effectively as a conventional polymer material, or plastic. The researchers layered a thin film of raw, unpurified egg white onto an indium tin oxide substrate, then gradually heated it to about 140 degrees Centigrade. Once the white was cooked, they fabricated the rest of the transistor. Test results showed that the egg white performed well as a dielectric (insulating) component.
The researchers also tested the egg white dielectric on flexible substrates and found that the transistor maintained its output while the substrate was bent, indicating a good potential for use in portable, flexible electronics.
That’s good so far but the real proof will be in the pudding, when the team puts albumen through durability tests including temperature and moisture tolerance.
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