30-05-2022 | By Robin Mitchell
Recently, researchers have demonstrated a new semiconductor material made entirely from paper-based materials that may have the ability to be used in wearable sensors and disposable electronics. What challenges do disposable electronics present, what did the researchers demonstrate, and could it lead to safe disposable electronics?
If there are two words that are rarely used in the same sentence, it’s electronics and disposable. Many aspects of modern life rely on something disposable with a short life span, whether it’s paper, packaging, surgical equipment, car tyres, or bin bags. But the effects on the environment on disposable items have been disastrous, with microplastics now being identified in human blood, animals consuming plastic waste thinking that it’s food or build-up of harmful compounds in soil from landfills.
The complexity of electronic devices and their price rarely sees electronics being used in a disposable manner, but that doesn’t mean that electronics are seldom disposed of. In fact, electronic waste continues to be a growing problem, especially when considering the large number of rare elements needed to manufacture them (such as platinum, gold, and palladium).
The growing amount of e-waste creates problems for the environment if not correctly disposed of, as harmful compounds can leech into the ground (and thus contaminate groundwater). Additionally, the increasing amount of e-waste also reflects the increase in global production of electronics, and this has a negative consequence on the environment through mining and refining operations.
Now that the desire for disposable electronics is growing with potential applications including IoT, IIoT, and asset tracking, researchers are now trying to find environmentally friendly solutions to realise such devices.
Recently, researchers from Japan have demonstrated a new semiconductor whose primary component is cellulose, the central component in paper. The researchers (who hail from Osaka, Tokyo, Kyushu, and Okayama) have created three-dimensional cellulose structures whose electrical conductivity can be tuned between 1012Ωcm to 10-2Ωcm by adjusting the number of charge carriers in the structure.
To create the semiconductor material, researchers used nanocellulose suspended in water, whose charge properties could be controlled with the doping of key elements. Once dried, the paper material is treated with iodine to protect the nanostructures that enable semiconductor operation.
The new cellulose material was then folded and cut to create complex macro structures (i.e., origami and kirigami) while still exhibiting its semiconductor properties. This demonstrates how the new material could be used to create flexible electronics in wearable applications. The researchers noted in their announcement that the new semiconductor could present opportunities for sensors designed to monitor biomarkers such as sweat and sugar that are safe to wear and easy to apply. Furthermore, using a paper-based semiconductor could help create electronics in the future that avoid harmful compounds and can be easily disposed of like any other biological matter.
Origami structure made from the semiconductor material
What the researchers have demonstrated here presents the engineering community with a very exciting opportunity for the field of disposable electronics. If proven to be reliable and practical, a paper-based semiconductor would not only be cheap to manufacture but would also allow for electronic devices to be thrown away without needing to consider the environmental effects. Furthermore, flexible paper-based electronics would most likely be safe to use in direct contact with skin, and this would open up opportunities for disposable health monitors.
Could this new semiconductor be the key to future electronics? Will its development lead to disposable electronics safe for the environment? Only time will tell, but it is clear that the researchers need to first demonstrate the material in a practical application.