Not only does material design mean electronic wearables are relatively fragile; the physical limitations of existing electronic materials presents a development barrier as well. If the material becomes damaged this leads to a decline in functionality or it renders the device inoperative altogether.
New research, carried out at from Penn State University, has focused on improving the durability of wearable electronics. A team led by Professor Qing Wang has come up with a flexible electronic material capable of repairing itself after a break. Self-healing, in this context, means after physical deformation, like being cut in half, a material repairs itself with no external influence.
In a statement, Professor Wang outlined the problem: “Wearable and bendable electronics are subject to mechanical deformation over time, which could destroy or break them.”
He further outlined the intended solution: “We wanted to find an electronic material that would repair itself to restore all of its functionality, and do so after multiple breaks.”
For this the research group rendered a material that can be used as a dielectric, placed inside wearable electronics. This substance is capable of self-repair even following multiple breaks. Each time it breaks, remarkably, the substance fully restores all of its original electronic properties.
A dielectric material is an electrical insulator that can be polarized by an applied electric field. Dielectric materials can be solids, liquids, or gases. Such materials are being used in electronics, optics, and solid-state physics.
Other research groups have developed dielectric material that retain electrical resistivity after self-healing. However, these materials lose their thermal conductivity, which means that electronic devices are at risk of overheating. The new material restores mechanical strength, breakdown strength to protect against surges, electrical resistivity, thermal conductivity and dielectric, or insulating, properties.
The effect can be seen in the following video, made at Penn State:
The technology has attracted interest on Twitter. For instance, tech company UPHIGH Productions (@Spikejjjjames) tweeted: “Self Healing Electronics – Behold The Future…”; and Usman Sheikh (@UsmanKSheikh), Global Head of Design & Experimentation @Barclaycard Future Payments, messaged: “This self-healing material could solve many wearable woes.”
Commenting on the video, Wang enthuses: “This is the first time that a self-healable material has been created that can restore multiple properties over multiple breaks, and we see this being useful across many applications.”
To construct the material, the researchers added boron nitride nanosheets to a base material of plastic polymer. Boron nitride shares some of the properties of graphene. Indeed, it is sometimes called ‘white graphene.’ The material is made up of equal numbers of boron and nitrogen atoms. The compound has excellent thermal and chemical stability. There was one key difference with graphene, material is a very good insulator of heat, and has the potential to “cool down” electronic devices. In addition, the material is impervious to moisture, which means it has potential as the basis for electrical devices to be used in baths and showers.
As to how the “self-healing” electronics works, this occurs because the boron nitride nanosheets connect to one another with hydrogen bonding groups functionalized onto their surface. As the two pieces are placed in close to each other, an electrostatic attraction draws the bonding elements close together. Each time the bond is broken, it rapidly re-connects.
The findings were published in the journal Advanced Functional Materials. The research paper is titled ”Metal Oxide Transistors via Polyethylenimine Doping of the Channel Layer: Interplay of Doping, Microstructure, and Charge Transport.”
This article is part of Digital Journal’s regular Essential Science columns. Each week we explore a topical and important scientific issue. Last week we examined a possible connection between the neurodegenerative disease and certain infections. The prior week we discussed a lens that can produce clear magnification of nanoscale objects. Remarkably the lens was made from paint whitener on a sliver of glass.
