Electronic circuitry that’s flexible, stretchable, and biodegradable

By Gary Elinoff, contributing writer   

A team at Stanford University created a semiconducting polymer that is easily biodegradable in the presence of nothing more than standard vinegar. Beyond being biodegradable, the polymer is also flexible and stretchable. Additionally, the group, headed by Stanford engineer Zhenan Bao, has created a biodegradable mounting substrate and a method to build actual electronic components, which are also easily biodegradable.

The many uses for biodegradable electronics

This advancement has the potential to lead to a reduction of approximately 50 million tons of electronic waste that is disposed of annually — a significant ecological cost to the planet. Devices using the new stretchable, flexible electronics will also benefit toward the development of wearable devices, as well as for devices to be surgically implanted within the human body.

The method is also noteworthy in that it doesn’t use the tiny amounts of gold usually needed by ICs, but rather employs iron. Iron is, of course, non-toxic to the environment. In the small amounts involved, the iron, even after the device it’s part of dissolves within a living person, is of no consequence to human health. As described in The Proceedings of the National Academy of Science (PNAS), the flexible, semiconducting polymer owes its biodegradability to reversible imine bonds. 

The substrate, ultrathin at 800 nanometers, is derived largely from cellulose. Modified fibers render the material transparent, as well as flexible and biodegradable. In addition to mounting the electronic components, the substrate can mold to the rough and smooth areas of human skin, and as the skin stretches, so can the substrate.

Flexible semiconductors can be attached to smooth or rough surfaces. Image Credit: Boa Lab.

Medical monitoring

Flexible, stretchable devices built with this new type of electronic can be comfortably worn on human skin for a period of about a week. All the while, they can monitor and record biological parameters such as blood pressure, glucose numbers, and a plethora of valuable biomarkers contained within sweat. Then they can be detached from the person and the data can be downloaded. Ultimately, the completely biodegradable unit can be cheaply and ethically discarded.

According to Boa, the residues of the polymer after biodegradation are so benign that they can be easily tolerated with the human body. This will eventually make sensors safe to be placed within the human body — a Fantastic Voyage indeed.