July 09, 2019 by Emily Gray-Fow
Waste, and especially electronics waste, is a major issue that humanity needs to tackle if it’s to keep this planet in a viable condition long-term. Bioengineers have been working increasingly closely with electronics engineers to resolve this issue with multiple breakthroughs in the last 12 months.
The development of organic and biodegradable electronics isn’t just a way to protect the environment from traditional manufacturing processes. New manufacturing methods could lead to reduced costs and create electronics that can be left in the environment without having to worry about leaving pollution behind for future generations.
It can also be a useful technique for creating things like medical implants and sensors that are biologically-safe (with previous implantable medtech, their traditional manufacturing processes could lead to chemicals being leached into the user's body). Finally, from a consumer point of view, the idea of protecting the environment could make it possible to sell such products at a premium.
Disposed-of cathode-ray computer monitors and keyboards, whose plastic enclosures ensure they are left in landfill indefinitely. Image courtesy of PxHere.
We try not to think about it too hard, but traditional electronics cause damage to people and the environment in several ways.
Here are a few examples:
All in all, it is clear that the current methods for creating electronics aren’t able to meet current demands without causing harm to people and the planet.
Traditional PCBs are plastic-based (as are many finished consumer electronics goods). Research into replacement materials has been ongoing for a number of years, giving us access to a number of alternatives.
Bioplastics are one of these.
An example of bioplastic, namely one made from a freshwater diatom named Didymo, aka Didymosphenia geminate. Image courtesy of Wikimedia.
Bioplastics can be based on wood, bloodmeal, yeast-produced lactic acid, and more. Not all biobased plastics are biodegradable, however, and in many cases, they still cost more than their fossil fuel-based counterparts. But in the right markets, consumers will pay a premium to protect the environment. These costs are also set to come down, or at least fall in line with, the cost of traditional plastics as oil prices rise.
Until recently, replacing other common materials like leather and soft foam plastic were a challenge. Finnish design studio Avian has recently proven that it is possible to replace these materials with fungus-derived foam and leather substitute. Their prototype Korvaa headphones show that it is possible to design high-end consumer electronics without resorting to unsustainable materials.
That said, for the direct replacement of plastic in PCBs, things are a little more complicated.
High-temperature soldering can cause plastics to deform and even catch fire if they don’t have the right properties. There has been some success with a sugar-based epoxy resin (glucopyranose, or GPTE) with high glass transition temperature (Tg), and diethylene-toluene-tetramine (DETDA) polymerising material, and with cellulose acetate (CA).
Both materials have their own issues with manufacturing due to cracking and temperature limitations, but progress is definitely being made on this front.
Of course, there is far more to electronics than just plastic.
Luckily, researchers can now produce completely biodegradable semiconductors made from polymers. It’s even possible to create electrodes that can be stretched and will degrade under the right circumstances.
The potential is there to create devices that don’t cause harm to the environment and can be safely used almost anywhere.
An eco-friendly 'lightbulb moment', which represents 'thinking green'. Image courtesy of Pixabay.
Going beyond a simple plastics replacement, biodegradable electronics may well be the future of less environmentally-damaging electronics. There are also plans to make use of electronics that can safely disappear inside the human body, with the potential for creating a whole new generation of safely consumable sensors and other medical equipment.
It is now possible to create transient electronics as effective sensors, cameras, antennas, and solar power sources that can be encapsulated in thicknesses of silk. The layers of silk determine how long the products survive inside the body before water ingress dissolves the electronics.
The potential medical uses of these electronics are vast. Animal studies have already shown viable implantation of transient sensors that monitor wound healing, blood pressure, and organ function. Combined with improvements in rectennas for the battery-free powering of such devices, we can expect to see human applications of this technology in the very near future.
The ability to create sensors from cellulose and other biodegradable materials has the capacity to give us the freedom to install sensors and other IoT devices anywhere in our environment without having to worry about the pollution aspect.
Recycling will also be much simpler, with the extraction of metal components made much easier if we can simply make the plastic parts of our used electronics ‘go away’.
Not only will medical devices be revolutionised: large-scale sensor networks will be possible anywhere, even in ecologically-sensitive locations.
As engineers, we need to start thinking about the ecological impact of the current electronics boom. These developments will soon enable us to choose a less damaging option in many different cases.
Those of us dealing with medical electronics are likely to get access to this technology the soonest, but anyone who is involved in the design and production of devices for use in our precious environment needs to keep an eye on these developments.
