Biodegradable electronics and their environmental footprint at end of life
Biodegradable electronics do not necessarily mean the absence of long-term environmental impacts. This is the key and somewhat unexpected conclusion of a study titled “End-of-Life usefulness of degradation by-products from transient electronics,” published in the scientific journal npj Flexible Electronics by researchers from Northeastern University.
The research systematically analyzes what happens over time to the by-products generated as electronic devices designed to dissolve after use degrade. The results show that even when devices visually disappear, microplastics, persistent polymers, and metal complexes can remain in the environment, with potential environmental and health effects.
Biodegradation does not automatically ensure environmental safety
According to researchers Sandhu and Dahiya, the mere ability of a device to disintegrate is not sufficient to define it as sustainable. The study explains that degradation involves complex interactions between organic materials, synthetic polymers, and metals.
These interactions can generate molecules with poorly understood chemistry, in some cases more persistent than the original materials. The findings come amid the rapid global growth of electronic waste, estimated at around 60 million metric tons per year and projected to reach 75 million tons by 2030, underscoring the urgency of more rigorous assessments of solutions marketed as sustainable alternatives.
Biodegradable electronics tested through an 18-month pressure sensor study
The first device examined by the researchers was a partially degradable capacitive pressure sensor made of silk fibroin, polyethylene oxide (PEO), copper, and a polyimide substrate. As reported in the study, the device was monitored for 18 months under controlled conditions.
Natural materials such as silk fibroin degraded relatively quickly, producing peptides and simple organic compounds. Copper, however, released Cu²⁺ ions that formed stable complexes. After 18 months, about 90% of the device had degraded, but some by-products remained in solution. The authors note that high concentrations of copper in soil can be harmful to plants and organisms, highlighting the need for targeted toxicological assessments.
Photodiodes and persistent polymer residues
The second case focused on a fully degradable photodiode based on a cellulose acetate substrate and PEDOT:PSS electrodes. The device was monitored for more than seven months in aqueous solutions with different pH levels. While cellulose acetate dissolved within a few weeks, Sandhu and Dahiya observed a very different behavior for PEDOT:PSS.
According to the data, complete degradation may take more than eight years, with the formation of polystyrene derivatives and microplastics described by the authors as “nearly non-degradable.” Even when no visible residues remain, instrumental analyses detected persistent polymer fragments.
Natural versus synthetic materials in biodegradable electronics
The study clearly distinguishes between natural materials and synthetic polymers. Cellulose and silk fibroin showed faster degradation rates and released by-products considered non-harmful.
In contrast, materials such as PEDOT:PSS, despite offering high electronic performance, raise significant environmental concerns. The research also points out that many biocompatibility assessments in the literature cover only days or weeks, while real degradation processes unfold over years.
Environmental impacts begin before end of life
Beyond the degradation phase, the Northeastern University study draws attention to the environmental impact of manufacturing processes. Electronics production remains largely linear and resource-intensive.
As the authors note, producing a single silicon wafer can require up to 6,000 liters of water, which then becomes contaminated wastewater. In a context of increasing global water stress, this production model appears incompatible with a truly sustainable vision of biodegradable electronics.
Rethinking how biodegradable electronics are defined
Sandhu and Dahiya argue for a clearer distinction between biodegradable, transient, compostable, and sustainable devices. Sustainability, as outlined in the study published in npj Flexible Electronics, must account for the entire life cycle, including material selection, manufacturing, degradation pathways, and the nature of degradation by-products.
Analyzing the device as a whole, rather than focusing solely on individual components, is essential to avoid a scenario in which reducing visible electronic waste leads to the spread of invisible but persistent pollutants.