Now You See It, Now You Don't

Planned obsolescence is a practice that has come into the spotlight in recent years, as a number of well-known companies have taken measures to ensure their electronic devices become paperweights long before their useful lifespan comes to an end. But that is not the only way electronics find their way to the trash heap — they can also legitimately become obsolete, be irreparably damaged, or simply no longer be needed.

This is a big enough problem for consumer electronics, where all of these items turn into e-waste that can leach toxic chemicals into the environment. But when it comes to implantable medical devices, like drug delivery systems and pacemakers, the stakes are much higher. When these implants are either no longer needed or come to the end of their useful life, they must be surgically removed. Needless to say, this entails the risk of complications that can threaten the life of the patient. Moreover, this additional work taxes an already strained healthcare system.

Researchers have been experimenting with biodegradable electronics as a potential solution to this problem. Ideally, a medical implant made from biodegradable materials would operate as long as it is needed, then simply dissolve into a harmless substance, eliminating the need for a second surgical procedure to remove it.

To date, these technologies are still rarely used, however. They tend to rely on the application of a third-party system that utilizes ultrasound or light, for example, to cause the device to break down. Unfortunately, these systems have proven to be prohibitively expensive and difficult for clinicians to use in practice.

A team led by researchers at Pennsylvania State University has come up with a way to work around these issues. Rather than being actively dissolved through a costly and complicated process, the team demonstrated how a specialized biodegradable encapsulation can delay the degradation of an implant. Through careful customization of that encapsulation, it is possible to specify exactly how long the device should stick around.

To find the right formula, the researchers experimented with many different materials in a computer simulation. The results of this work revealed that silicon dioxide flakes were the best candidate material for the controlled degradation of an electronic implant. Furthermore, the team worked out exactly how the ratio of the width to the thickness of the encapsulation controls the degradation rate. With this knowledge, an implant can be designed that will dissolve at a predetermined point in the future.

Before degradation, the implants fully retain their original mechanical properties. Experiments showed that devices remained fully functional for 40 days in one case. Moreover, the technology is inexpensive to implement, simple to manufacture, and much less complicated for medical professionals to work with when compared to existing systems.

In conjunction with their encapsulation method, the team also integrated many types of dissolvable electronic components, including n-channel metal-oxide-semiconductor field-effect transistors, complementary metal-oxide-semiconductor arrays, capacitors, radio frequency coils, and wireless light-emitting diode arrays. The encapsulation was shown to be capable of protecting these components and keeping them in service until the appointed time for the implant’s degradation. The unique properties of this system position it well to be the leading option for encasing temporary medical implants in the future.