Biodegradable electronics require full life cycle assessment
The term biodegradable electronics does not automatically imply long-term environmental safety. This is the main conclusion of the study End-of-Life usefulness of degradation by-products from transient electronics, published in npj Flexible Electronics by researchers at Northeastern University in Boston.
The research provides a systematic assessment of what happens to the by-products generated as electronic devices designed to dissolve after use gradually degrade. The findings show that, even when the devices disappear from view, microplastics, persistent polymers and metal complexes can remain in the environment, potentially posing environmental and health risks.
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Biodegradation alone does not guarantee environmental safety
According to researchers Sandhu and Dahiya, the mere ability of a device to break down is not enough to classify it as sustainable. The study explains that complex interactions occur during degradation between organic materials, synthetic polymers and metals.
These interactions can generate molecules whose chemistry is not yet fully understood and that may prove more persistent than the original materials. The research comes at a time when global electronic waste is estimated at around 60 million tonnes per year, with volumes expected to reach 75 million tonnes by 2030, highlighting the urgent need for more rigorous assessments of technologies promoted 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 from silk fibroin, polyethylene oxide (PEO), copper and a polyimide substrate. As reported in the study, the device was monitored under controlled conditions for 18 months.
The results showed that natural materials such as silk fibroin degraded relatively quickly, producing peptides and simple organic compounds. Copper, however, released Cu²⁺ ions, which formed stable complexes. After 18 months, approximately 90% of the device had degraded, yet part of the degradation by-products remained in solution. The authors note that high copper concentrations in soil can be harmful to plants and other organisms, underlining the need for targeted toxicological assessments.
Photodiodes reveal persistent synthetic polymers
The second case study focused on a fully degradable photodiode built on a cellulose acetate substrate with 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 found that PEDOT:PSS behaved very differently. According to the study, complete degradation may take more than eight years, producing polystyrene derivatives and microplastics described by the authors as “almost non-degradable”. Instrumental analyses detected persistent polymer fragments even when no visible residues remained.
Natural and synthetic materials show very different behaviours
The research clearly distinguishes between natural materials and synthetic polymers. According to the authors, cellulose and silk fibroin degrade more rapidly and release by-products that are considered non-harmful.
By contrast, materials such as PEDOT:PSS, while delivering high electronic performance, raise significant environmental concerns. The study also highlights that many biocompatibility assessments available in the scientific literature cover only a few days or weeks, whereas actual degradation processes unfold over several years.
The environmental challenge starts before end of life
Beyond the degradation phase, the Northeastern University study also draws attention to the environmental burden associated with electronics manufacturing. Electronic production remains largely linear and highly resource-intensive.
As the authors note, manufacturing a single silicon wafer can require up to 6,000 litres of water, much of which ultimately becomes contaminated wastewater. Against the backdrop of increasing global water stress, this production model appears difficult to reconcile with genuinely sustainable biodegradable electronics.
Rethinking what biodegradable electronics really means
Sandhu and Dahiya argue for a clearer distinction between biodegradable, transient, compostable and sustainable electronic devices. As explained in their study published in npj Flexible Electronics, sustainability should encompass the entire product life cycle, including material selection, manufacturing, degradation pathways and the characteristics of the resulting by-products.
Assessing the device as a complete system, rather than evaluating only its individual components, is essential to ensure that reducing visible electronic waste does not simply result in the release of invisible but persistent pollutants.