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Electronics have a tremendous impact on human society. It is widely used in almost every field including healthcare, telecommunication, etc. Biodegradable electronics (or transient electronics) built with water-soluble, biocompatible active and passive organic materials can provide multifunctional operations for diagnostic and therapeutic purposes. These materials are generally considered non-toxic and safe. This is an emerging technology which deals with materials that have the unique ability to dissolve, resorb, or physically disappear in physiological environments in a controlled manner. The main applications of transient electronics are found in the production of eco-friendly sensors, temporary biomedical implants, and data-secure hardware.
Biodegradable electronics are used as an alternative to electrical medical implants. As temporary implants, they can be safely absorbed by the body after fulfilling their therapeutic functions. Biodegradable sutures or cardiovascular stents have a limited service life due to their ability to degrade. Organic electronic devices are generally fabricated on paper and aluminum foil acting as compostable material platforms.
Recent research conducted in 2018 has led to the development of biodegradable polymers that can disintegrate without full chemical breakdown, as well as those that can be recycled into monomeric and oligomeric building blocks. In 2012, researchers at the University of Illinois and Northwestern University in collaboration with the Tufts University have developed electronic implants using a mixture of magnesium and silicon encased in a silk protein. Preliminary research was carried out on lab rats, which revealed that the device is capable of eliminating bacterial infection in a wound using heat.
University of Illinois demonstrates transient electronics made of silk.
The device incorporated into the rats, except the silk coating, was completely dissolved three weeks after its initial application. The silk protein casings later disappeared more slowly compared to magnesium and silicon. The size of the implants can be adjusted for human use.
In 2009, Bettinger CJ et al. from Stanford University in California fabricated a biocompatible and biodegradable transistor composed of gold and silver electrodes and substrates and the dielectric made of biodegradable polymers. The transistor was shown to perform well in operating simple devices that are used for biosensing. The team placed the device in a citrate buffer to measure its disintegration ability in a biological environment. The device was found to be relatively intact followed by a significant uptake of water and loss of mass. The device was completely dissolved in the buffer after around 50 days.
Three application areas of biodegradable electronics seem to be promising:
- Medical implants that perform short-term diagnostic or therapeutic functions for a limited time period and dissolve and resorb in the body.
- Compostable consumer electronic systems for eliminating electronic waste streams created by frequently upgraded devices that include mobile phones and other portable devices.
- Wireless environmental sensors used in oil spills, which degrade over a time frame to reduce any ecological impact.
Researchers working with flexible biodegradable electronics now try to find out components that can be easily disintegrated when used in biodegradable devices. They focus on magnesium rather than using copper or silver for electrical connections as magnesium is very reactive under wet conditions. Scientists hope that the degradation of devices can be controlled by changing the thickness of silicon and adjusting the properties of silk. Another group of researchers are developing biodegradable electronics using organic materials other than silicon as they tend to dissolve more readily. However, the electrical and optical properties of other organic materials are not as good as silicon. The next challenge lies in gaining knowledge about the utilization of the devices for specific diseases. Organic electronic devices have proved to be versatile for various applications. However, further investigation on organic electronics could lead to the realization of new classes of electronic bioresorbable medical devices for human use.
Can Biodegradable Electronics Help Solve the Problem of e-Waste?
Researchers from Stanford University have developed a new device that completely disintegrates within a month when exposed to a mild acid. The material reflects the latest advancements in the field of “transient electronics,” which researchers hope will help address the massive buildup of electronic waste that has accompanied rapid advances in technology. The United Nations Environment Program has projected that almost 50 million tons of electronics will be discarded this year alone. Polymer-based electronics, also known as organic electronics, have attracted lots of interest in recent years because they comprise of commonly available raw materials and their manufacturing process is more environment friendly than that of silicon-based electronics. Recent research is extensively focusing on developing such polymer-based electronics that can be broken down easily by the environment. Examples, where this material could be used, include disposable skin patches to monitor blood pressure, glucose, or other biological functions. Alternatively, the devices could be implanted inside the body and then resorbed once they were no longer needed and, thereby, reducing the littering of the environment.
Sources and Further Reading
This article was updated on 13th February, 2020.