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Materials Science in Additive Manufacturing Biodegradable sustainable electronics

in electronic chips. Obtaining green materials, eco-
friendly fabrication processes, and devices with low
embodied energy have become prerequisite for sustainable
electronics moving forward. There is a growing need
for the development of biodegradable materials that
can partially or completely degrade into non-toxic
material under normal environmental and physiological
conditions. Electronics fabricated using these materials are
termed as transient electronics as they disintegrate fully
or partially after a certain period of steady operation. The
development of biodegradable electronic materials and
devices that safely degrade at the end of their life cycle will
reduce the financial costs, health care, and environmental
risks and streamline the waste management system. The
emerging technology of biodegradable electronics has
expanded opportunities in many sectors, such as solar
cells, batteries, and plant monitoring sensors with main
influence being in health care (Figure 1). In this review,
we discuss the emergence of biodegradable materials,
which have application in electronics. The biodegradable
materials, namely, conductors, semiconductors, and
insulators and dielectrics, are categorized according to their
electrical performance. The paper also discusses emerging
functional materials such as inks and pastes that are being
used in additive manufacturing and printed electronics.
The dissolution chemistry of the materials is discussed
in detail with emphasis on the electrical performance.
Finally, the review discusses the recent developments in
the field of electronics and their end of life and highlights
the challenges associated with the biodegradable materials
and their applications. Figure 1. Schematic diagram illustrating various categories of
biodegradable materials and their application in electronics.
2. Biodegradation mechanism
mainly includes hydrolysis and photolysis. Hydrolysis
The biodegradation of the materials into its smaller in water is often accelerated by the presence of acids and
constituents generally involves the process that is either bases. Photolysis is a light-induced redox reaction, which
influenced by biotic means that involve microorganisms breaks the constituents wherever the light can reach.
such as fungi and bacteria or abiotic means that involve
hydrolysis, photolysis, or oxidization. In nature, both 2.1. Dissolution chemistry
biotic and abiotic mechanisms exist together and the In studying biodegradable materials, most of the research
whole degradation is a sum of both. The degradation of the has been focused on dissolution rates, wherein a material
materials is affected by many factors external (environment) breaks up into smaller group of molecules or constituents in
and internal (molecular structure). There are mainly two a solvent. In general, investigations on the dissolution rates
different types of degradations categorized as biotic and of biodegradable materials do not involve microorganisms.
abiotic. Biotic degradation, also referred to metabolic Research in dissolution chemistry of biodegradable
degradation, leads to disintegration of the material materials involves dissolving them in suitable solvents or
through the change in their physicochemical properties hydrolysis in water or biofluids. Dissolution rate of various
through microorganisms. Most materials are degraded by biodegradable electroactive materials is given in Table 1.
microbial attack in a single step. Biotic degradation is the The mechanisms and kinetics of dissolution and their
most significant removal pathway of contaminants from reaction products are important for potential application
the natural environment. If the biological activity is the of biodegradable materials in eco-friendly electronics,
predominant influence in the breakdown of a material, biomedical devices, and environmental sensors. All the
then it is referred to as abiotic degradation. The process investigations involving degradation of metals follow the

Volume 1 Issue 3 (2022) 2 https://doi.org/10.18063/msam.v1i3.15