Controlling the dissolve rate of biodegradable electronics

A challenge with these water-soluble devices has been controlling their degradation rate to ensure they last long enough to fulfil their medical purpose. Recent research has made strides in this area by developing methods to control the dissolve rate of these biodegradable electronics through the use of dissolvable elements, like inorganic fillers and polymers, which encapsulate the device.

The research team, led by Huanyu “Larry” Cheng, the James L. Henderson, Jr. Memorial Associate Professor of Engineering Science and Mechanics at Penn State, published their findings in Advanced Functional Materials.

Ankan Dutta, co-first author on the paper, doctoral student in engineering science and mechanics, and fellow of the Cross Disciplinary Neural Engineering Training Program at Penn State, highlighted the importance of this development: “Biodegradable electronics enable patients to have one surgery instead of two, as they do not need to undergo a second operation to remove the implant once it is in place, but we still need the device to last long enough to accomplish its medical purpose.”

Dutta and the team developed an encapsulation strategy that allows a device to remain in the body without degrading for over 40 days while retaining its mechanical properties, surpassing previously reported devices. Encapsulating a biodegradable device using zinc oxide- or silicon dioxide-based fillers allowed the device to break down more slowly and, therefore, work for longer periods.

Dutta used modelling software to analyse how different materials and designs impacted the onset of degradation of the electronic implant in the body. The team found that coating the device in silicon dioxide flakes worked best to control the degradation rate. Modelling also revealed that the ratio of the width and thickness of the encapsulation, or aspect ratio, played a role in predicting the degradation onset of the device.

Dutta explained: “Inexpensively, we can fine tune how fast a device will degrade based on the aspect ratio, the types of materials used and how many fillers were used. We are achieving what we call ‘on demand transient electronics,’ where we passively control how fast an implant degrades inside a body based on its materials.”

Collaborators at Korea University (KU), led by co-corresponding author Suk-Won Hwang, associate professor in the KU-Korea Institute for Science and Technology (KIST) Graduate School of Converging Science & Technology, utilised Dutta’s simulations to fabricate a prototype of a biodegradable implant.

Hwang commented: “A high-efficiency biodegradable encapsulation approach can significantly increase the functional lifetime of electronic devices, which consist of a biodegradable polymer matrix and a biodegradable organic filler, to create a dispersed composite solution. The composite solution was cast into a film, allowing for large-scale production without additional treatments, enhancing its practical applicability.”

In past research, detailed in a review paper co-authored by Dutta and Cheng and published in Nanoscale in 2023, the researchers explored active degradation of implants. This method uses third-party systems like ultrasound or light technology to trigger a device to break down from outside the body. However, they found that the practice can be costly and challenging in clinical settings.

Dutta stated: “Devices that passively degrade on their own without the use of third-party systems are both inexpensive and more feasible to potentially use in a patient care setting in the future.”