Biodegradable Flexible Electronics: A New Option for Greater Sustainability

Key Takeaways

• Biodegradable flexible electronics integrate different aspects of design.

• The application of biodegradable flexible electronics may influence long-term design patterns and result in new types of EDA software.

• The potential of biodegradable electronics may provoke new levels of creativity in electronic and PCB design.

In 2009, a Danish scientist’s experiments to detect any changes in the chemistry of harbor mud disclosed something new: although the mud contained large quantities of hydrogen sulfide at the outset, one segment lost all traces of the chemical after 30 days.

Why did this happen? The question puzzled scientists until they discovered the shocking reason—bacteria had built organic electrical cables by joining end-to-end. The newly named “cable bacteria” had electrically chained together to find oxygen.

The Danish scientist’s discovery of cable bacteria led to new observations that uncovered “nanowire bacteria” that grow protein structures that can move electrons. While cable bacteria create cylinders of conductive wires that surround cell chains, nanowire bacteria transfer electrons gained from oxidation through protein nanowires to cells. Researchers have already begun to contemplate how the relatively high conductivity of cable and nanowire bacteria may serve to power small devices.

Researchers have found that the actions of cable bacteria can assist with detecting and cleaning pollutants and toxic chemicals from aquifers, wetlands, and wastewater sites. In addition, research has shown that cable bacteria reduce concentrations of methane.

The discovery of “cable bacteria” reminds us that much of what we design somehow mimics nature. However, for decades, the electronics industry has run counter to environmental needs by using toxic compounds to manufacture semiconductor components and printed circuit boards, by producing throw-away devices that may never break down in landfills, and by ignoring environmentally damaging mining practices in third-world nations.

The Industry Shift to an Emphasis on Design for Sustainability

The step-by-step shift away from those practices to a true emphasis on design for sustainability and design for environment principles has changed—and will continue to change—the electronics and printed circuit board industries. 

For example, a requirement of the European Union Restriction of Hazardous Substance (RoHS) directive has pushed manufacturers away from using lead, hexavalent chromium, polybrominated biphenyls, and other chemicals when producing printed circuit boards. In turn, the elimination of hazardous chemicals has allowed companies to reduce the costs associated with disposal, recycling, and wastewater treatment.

Biodegradable Flexible Electronics Offer a New Path Forward

With biodegradable flexible electronics, researchers have taken another step that brings the business and science of electronics full-circle. The discovery of nanocellulose and biopolymer films as primary materials for electronic circuitry has led to the design and production of electronic devices that degrade to compost at the end of operating life. In addition to allowing manufacturers to offer easily disposable, environmentally friendly devices for consumers and industries, the different types of films establish new paths for developing flexible electronic devices.

Those devices—referred to as flexible hybrid electronics—serve as examples of design thinking that focuses on the consumer and inventive rethinking that pushes creativity to new levels. The capability to combine technologies such as paper substrates, conductive inks, biodegradable plastics, 3D printed components, and organic power supplies has led to breakthroughs in small form factor devices poised to become part of the mainstream. Those breakthroughs include biocompatible optics constructed from silk proteins extracted from silkworm cocoons to living nanoscale optical devices.

Design Applications

Research into biodegradable flexible electronic design applications has pushed the electronics industry from a single-strand focus on electronics to a multi-focus that includes:

• 3-D printing

• Biology

• Mechanical design

• Environmental science

Implantable Devices

The possibility of new applications for wearable or implantable devices that conform to the shape of human tissue requires collaboration at all levels. While some members of an integrated design team may concentrate on signal transmission, others may focus on the ability of a flexible hybrid electronic device to harmlessly dissolve in bodily fluids after the device has satisfied its objectives.

Nano-Sized Embedded Sensors

A similar integration occurs during the design of flexible nano-sized embedded sensors for transportation, aerospace, or robotic applications. For example, biodegradable flexible electronics may serve as the springboard for soft robotic applications. In contrast to current mechanical robotic applications, soft robotics seeks the development of artificial electronic skin, soft sensors, and flexible power sources. Soft robotics research may lead to new types of prosthetic devices or humanoid robots that have increased flexibility and dexterity.

New Technology Introduces New Challenges

Designing biodegradable flexible electronic devices presents unique challenges for electronics system design and PCB design. 

Predicting the capability of new polymers and composites to shield against electromagnetic interference may require new design techniques and EDA software applications. Design teams may need new methods for simulating the impact of resistance changes, capacitive coupling, or inductive coupling on organic semiconductors. The opportunities for impedance mismatches may also change for devices that use breakthrough connecting materials that stretch and conform to unique shapes or embed in animal or human tissue or new composite materials.

In terms of the convergence between mechanical design and electronic design, the use of flexible hybrid devices may push EDA software to new limits. Mechanical design software tools now need to account for both the capability of flexible circuits that can conform to unique shapes and the resourcefulness given through 3D printing. Electronic design now involves the analysis of circuits that become integral parts of different types of materials and that may become exposed to harsh environments.

The Future of Biodegradable Flexible Electronics 

The future of biodegradable flexible electronics may evolve into designs for a wide range of consumer, medical, and industrial applications. Research teams have already shown that the bacteria can power LEDs and cellphone circuits. New research suggests that the bacteria could help form a new generation of wearable devices that include nano-sized biological and environmental sensors. As time goes on, new developments in biodegradable flexible electronics will continue to shape a more sustainable future for the  electronics industry.

For the latest developments in the industry, including breakthroughs in biodegradable flexible electronics, check out our PCB Design and Analysis Software page.  Allegro PCB Editor can help you with your next biodegradable electronics project.

If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.