A robot that endures over one million uses -- Then becomes compost to nourish plants

Seoul National University College of Engineering

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Fully compostable soft robot system

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Credit: © Nature Sustainability, originally published in Nature Sustainability



The rapid proliferation of robots and electronic devices is placing the world under a new and growing environmental burden. According to the United Nations Institute for Training and Research (UNITAR), global electronic waste (e-waste) reached approximately 62 million metric tons in 2022, a significant portion of which was neither properly collected nor recycled but instead landfilled or incinerated. As soft robots are increasingly adopted across diverse sectors—including healthcare, agriculture, and environmental exploration—end-of-life robotic systems are emerging as a new source of next-generation e-waste. In particular, soft robots and their associated electronic systems are typically constructed from multilayer thin-film architectures composed of thermoset polymer elastomers, metal alloys, and extrinsic semiconductors. These heterogeneous material combinations make recycling virtually impossible and prevent natural degradation, leading to growing concerns that such technologies are fundamentally unsustainable.

 

In response to these challenges, a SNU–Sogang–JKU joint research team led by Professor Seung-Kyun Kang at Seoul National University, Professor Sang-Yup Kim at Sogang University, and Professor Martin Kaltenbrunner at Johannes Kepler University Linz has developed a fully biodegradable and compostable soft robotic electronic system that maintains high performance and durability during operation yet completely returns to nature after use. The team employed a water-free biodegradable elastomer, poly(glycerol sebacate) (PGS), as the structural material for the robotic frame, enabling the realization of soft actuators with low hysteresis and excellent elastic recovery. The PGS-based bending actuator exhibited remarkable durability, maintaining nearly unchanged bending angles and output forces even after one million actuation cycles, and preserving stable performance after long-term storage. In addition, biodegradable inorganic electronic components composed of magnesium (Mg), molybdenum (Mo), and silicon (Si) were integrated to incorporate curvature, strain, tactile, temperature, humidity, and pH sensors, along with heaters, electrical stimulators, and drug-delivery modules, into a single soft robotic finger—demonstrating a highly integrated, multifunctional biodegradable electronic platform. When the entire robotic system was subjected to industrial composting conditions, both the structural framework and electronic components decomposed within a few months. Plant growth tests conducted using the resulting compost confirmed the absence of environmental toxicity.

 

Professor Kang stated, “This research overcomes the limitations traditionally associated with biodegradable materials and demonstrates soft robotic and electronic systems with practical levels of durability and performance, setting a new benchmark for sustainable robotics.” Dr. Kyung-Sub Kim added, “By simultaneously achieving high performance, complete biodegradability, and ecological safety, this platform is expected to serve as a foundational technology for the transition toward environmentally responsible robotics and electronics.” The study presents a fundamental solution to the growing waste problem associated with robotics and electronic devices and introduces a new paradigm in which intelligent machines complete their missions and return to the soil—not as waste, but as part of nature.

The study was published in Nature Sustainability

https://doi.org/10.1038/s41893-026-01780-4

A video demonstration is available here:

https://youtu.be/AFVIGgntKm8?si=t6gc0rbqwgoCnCQu

 

□ Introduction to the SNU College of Engineering

Seoul National University (SNU) founded in 1946 is the first national university in South Korea. The College of Engineering at SNU has worked tirelessly to achieve its goal of ‘fostering leaders for global industry and society.’ In 12 departments, 323 internationally recognized full-time professors lead the development of cutting-edge technology in South Korea and serving as a driving force for international development.

 

Branch pruning via joule heating (left) and a drug delivery system for plant treatment (center and right)

 

Biodegradation of the soft robotic finger

Credit

© Nature Sustainability, originally published in Nature Sustainability

Journal

Nature Sustainability

DOI

10.1038/s41893-026-01780-4 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Biodegradable yet hyperdurable robotic fingers for zero-waste soft electronics

Article Publication Date

15-Mar-2026

 

Turning waste into climate gains: Co-pyrolysis of cotton straw and plastic mulch could cut millions of tons of CO₂ in Xinjiang

Maximum Academic Press

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Through a comprehensive life cycle assessment (LCA) , the team demonstrated that converting these wastes into biochar via pyrolysis—particularly by co-processing cotton straw with recycled mulch film—could cut carbon emissions by millions of tons annually while simultaneously addressing the region’s persistent “white pollution” from residual agricultural plastics.

Agricultural residues in Xinjiang pose both environmental pressures and climate opportunities. In 2023, maize, wheat, and cotton production exceeded 24 million tons, generating about 33.9 million tons of straw, of which 26.4 million tons are collectible. While wheat straw is mostly returned to fields and maize straw used as feed, cotton straw—produced in a region accounting for 85% of China’s cotton area—is often underutilized or burned. Plastic mulch film, covering over 60% of cropland, adds to the challenge; despite an 81% recovery rate, more than 200,000 tons remain recyclable annually. Converting these wastes into biochar via pyrolysis could enhance carbon sequestration and cut emissions, yet integrated regional assessments remain limited.

A study (DOI:10.48130/aee-0025-0016) published in Agricultural Ecology and Environment on 28 January 2026 by Ronghua Li’s & Jianchun Zhu’s team, Northwest A&F University, provides a regionally grounded, life cycle–based framework showing how integrated co-pyrolysis of crop straw and plastic mulch can simultaneously reduce carbon emissions, mitigate agricultural plastic pollution, and enhance soil sustainability.

Using regional agricultural statistics, crop-specific straw-to-grain ratios, collection coefficients, and mulch film recovery rates, the researchers first quantified the available biomass resources in Xinjiang, and then applied a LCA framework to evaluate net CO₂e balances from feedstock collection, pyrolysis, transport, renewable energy substitution, soil carbon sequestration, N₂O mitigation, fertilizer savings, and associated emissions. The analysis showed that in 2023 maize, wheat, and cotton production generated 1.36 × 10⁷, 7.68 × 10⁶, and 1.25 × 10⁷ t of straw, respectively, with 2.64 × 10⁷ t collectively recoverable; meanwhile, mulch film use reached 2.5 × 10⁵ t, of which 2.03 × 10⁵ t was recyclable. If all collectible straw were pyrolyzed, biogas could generate 5.39 × 10⁹ kWh of electricity, offsetting 4.54 × 10⁶ t CO₂, while 8.76 × 10⁶ t of biochar could be produced, sequestering 4.62 × 10⁶ t of stable carbon (1.70 × 10⁷ t CO₂). Additional benefits included a 241.53 t reduction in N₂O emissions (7.2 × 10⁴ t CO₂e) and 8.06 × 10³ t CO₂e avoided from reduced fertilizer use, even after accounting for 1.12 × 10⁶ t CO₂e from logistics, yielding a net reduction of 2.05 × 10⁷ t CO₂e. Considering current uses of wheat and maize straw, cotton straw alone (9.29 × 10⁶ t) could deliver a net reduction of 1.01 × 10⁷ t CO₂e. In contrast, mulch film pyrolysis alone produced limited biochar (3.35 × 10³ t) and a net reduction of 2.67 × 10⁵ t CO₂e. However, co-pyrolyzing all recyclable mulch film with cotton straw at a 1:4 ratio significantly improved performance, generating 2.24 × 10⁵ t of biochar and achieving a net reduction of 3.43 × 10⁶ t CO₂e, with further potential reductions of 9.34 × 10⁶ t CO₂e from treating the remaining cotton straw.

Overall, this study demonstrates that integrating cotton straw and plastic mulch management through co-pyrolysis can convert two persistent agricultural wastes into a powerful climate mitigation solution. Compared with treating plastic alone, co-pyrolysis significantly boosts biochar yield and carbon reduction efficiency. In addition to lowering emissions, biochar enhances soil quality and resource use efficiency, supporting sustainable cotton production and offering a scalable model for residue valorization in cotton-growing regions worldwide.

###

References

DOI

10.48130/aee-0025-0016

Original Souce URL

https://doi.org/10.48130/aee-0025-0016

Funding information

This study was funded by the Shaanxi Science and Technology Innovation Team Project (Grant No. 2025RS–CXTD–032).

About Agricultural Ecology and Environment

Agricultural Ecology and Environment (e-ISSN 3070-0639) is a multidisciplinary platform for communicating advances in fundamental and applied research on the agroecological environment, focusing on the interactions between agroecosystems and the environment. It is dedicated to advancing the understanding of the complex interactions between agricultural practices and ecological systems. The journal aims to provide a comprehensive and cutting-edge forum for researchers, practitioners, policymakers, and stakeholders from diverse fields such as agronomy, ecology, environmental science, soil science, and sustainable development.

---

DOI

10.48130/aee-0025-0016 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Potential of biochar production and carbon emission mitigation through co-pyrolysis of cotton straw and mulch film waste in Xinjiang, China

 

When waste becomes fertilizer: Can sludge-derived liquids reshape aquatic life in farmlands?

Maximum Academic Press

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The findings provide critical insights into the environmental trade-offs of recycling sludge-derived liquids in agricultural systems.

Hydrothermal carbonization (HTC) is an emerging technology for converting sewage sludge and other high-moisture organic wastes into reusable products without energy-intensive drying. In addition to producing hydrochar, HTC generates a nutrient-rich liquid byproduct known as HAP, into which a substantial fraction of organic matter, nitrogen, and phosphorus is transferred. Owing to its high nutrient content, HAP has been proposed as a soil amendment to reduce synthetic fertilizer inputs and enhance crop productivity. However, agroecosystems—particularly flooded systems like rice paddies—rely on complex microbial communities at the soil-water interface. How HAP affects periphyton biofilms and their ecological functions remains insufficiently understood.

A study (DOI:10.48130/aee-0025-0012) published in Agricultural Ecology and Environment on 29 December 2025 by Huifang Xie’s team, Nanjing University of Science and Technology, reveals how sludge-derived hydrothermal byproducts reshape microbial networks and ecosystem multifunctionality, providing a mechanistic basis for evaluating the ecological risks of nutrient recycling in agricultural systems.

Using controlled microcosm experiments, researchers exposed periphyton communities to gradient concentrations of sludge-derived HAP and comprehensively assessed water physicochemical properties, microbial diversity and composition (Shannon, Chao1, NMDS), community assembly processes (niche breadth and normalized stochasticity ratio, NST), interdomain bacterial–eukaryotic networks, trophic functional profiles (FUNGuild, FAPROTAX), ecosystem multifunctionality, and predicted metabolic pathways (MetaCyc). HAP rapidly altered water chemistry, initially suppressing dissolved oxygen—especially at high concentrations—while sharply increasing nitrogen loads; however, DO gradually recovered through photosynthesis, and NH4+-N, TN, and COD declined over time, with removal rates reaching up to 55% for COD and 35% for ammonium, demonstrating partial purification capacity. Although periphyton biomass decreased with increasing HAP, α-diversity remained stable, whereas β-diversity shifted significantly, with enrichment of Bdellovibrionota and Chlorophyta and declines in Firmicutes and Mucoromycota. Niche breadth narrowed, particularly for eukaryotes, and bacterial assembly became more stochastic under higher HAP stress. Network analyses revealed reduced connectivity, density, and complexity, alongside intensified competition and functional shifts toward chemoheterotrophy and nitrogen fixation. Environmental variables explained over 70% of community variation. Importantly, ecosystem multifunctionality declined significantly with increasing HAP and was strongly associated with community structure, niche breadth, and network complexity rather than species richness. Metabolic predictions further showed suppression of key biosynthetic and nutrient metabolism pathways and enhancement of stress-related pathways, indicating adaptive but insufficient compensation. Overall, the findings demonstrate that HAP reshapes community assembly, trophic interactions, and functional expression in periphyton, with network integrity emerging as the primary driver of ecosystem functioning.

This study underscores the dual nature of sludge-derived HAP as both a nutrient resource and an ecological stressor. While periphyton can partially buffer HAP inputs by maintaining nutrient removal capacity, excessive application disrupts microbial network integrity and reduces ecosystem multifunctionality. These findings highlight the need for ecological risk assessments that move beyond nutrient removal efficiency to include trophic interactions and interdomain network complexity. Careful optimization of HAP dosage and monitoring of microbial indicators will be essential to achieve sustainable nutrient recycling without compromising agroecosystem resilience.

###

References

DOI

10.48130/aee-0025-0012

Original Souce URL

https://doi.org/10.48130/aee-0025-0012

Funding information

This work was supported by the National Key Research and Development Program of China (Grant No. 2024YFD1700300), and the National Natural Science Foundation of China (Grant Nos 42107398 and 42277332). Yanfang Feng thanks the support of the '333' High-level Talents Training Project of Jiangsu Province (Grant No. 2022-3-23-083).

About Agricultural Ecology and Environment

Agricultural Ecology and Environment (e-ISSN 3070-0639) is a multidisciplinary platform for communicating advances in fundamental and applied research on the agroecological environment, focusing on the interactions between agroecosystems and the environment. It is dedicated to advancing the understanding of the complex interactions between agricultural practices and ecological systems. The journal aims to provide a comprehensive and cutting-edge forum for researchers, practitioners, policymakers, and stakeholders from diverse fields such as agronomy, ecology, environmental science, soil science, and sustainable development.

---

DOI

10.48130/aee-0025-0012 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Sludge-derived hydrothermal carbonization aqueous phase regulates agro-ecosystem multifunctionality by affecting cross-trophic community in periphyton

From straw to soil signals: How humification reshapes microbial life and resistance genes

Maximum Academic Press

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By simulating lignocellulose transformation at different temperatures, they found that high-temperature humic substances stimulate microbial carbohydrate-active enzyme genes and viral auxiliary metabolic functions. Meanwhile, elevated phenolic compounds from lignin breakdown strongly correlate with increased antibiotic resistance gene abundance.

Humification of lignocellulosic biomass is fundamental to soil fertility, microbial stability, and carbon sequestration, generating humic substances that act as long-term carbon reservoirs and energy sources. Yet organic matter composition also shapes microbial competition, viral interactions, and stress responses. Certain compounds, such as phenols, can induce oxidative stress and promote antibiotic resistance gene (ARG) transfer. Soil viruses further influence these dynamics through the “Piggyback the Winner” strategy, transferring auxiliary metabolic genes that enhance host carbon metabolism and competitiveness. Despite their ecological importance, the environmental consequences of lignocellulose-derived compounds during humification—particularly the link between phenolic compounds and ARG enrichment—remain insufficiently understood.

A study (DOI:10.48130/aee-0025-0013) published in Agricultural Ecology and Environment on 05 December 2025 by Xiangdong Zhu’s team, Chinese Academy of Sciences, reveals how lignocellulose-derived humification simultaneously enhances soil carbon metabolism and drives antibiotic resistance gene enrichment, highlighting a critical ecological trade-off in agricultural residue management.

To simulate natural humification and investigate its ecological consequences, the researchers first synthesized artificial humic substances from rice straw using hydrothermal liquefaction at 210, 270, and 330 °C, thereby selectively decomposing hemicellulose, cellulose, and lignin. These materials (HL210, HL270, HL330) were adjusted to equal total organic carbon concentrations and added to paddy soils to isolate compositional effects from carbon quantity. Chemical characterization was conducted using excitation–emission matrix spectroscopy, GC–MS, and ESI FTICR MS to determine molecular composition and structural transformation. The results showed that higher temperatures (270 and 330 °C) promoted lignin decomposition, increased fatty acids, humic-like substances, and phenolic compounds, and shifted molecular structures from lignin/CRAM-like compounds toward lipids and aliphatic molecules with lower O/C ratios and reduced polarity. Soil total carbon content increased in all treatments without altering basic soil properties such as pH and cation exchange capacity. Metagenomic analysis based on the CAZy database was then performed to assess microbial carbon metabolism. Following humic substance addition, glycoside hydrolase (GH) genes significantly increased from 60.95% to 83.71%, particularly in HL330-treated soils, while glycosyl transferases (GT) and carbohydrate-binding modules (CBM) decreased proportionally. Enrichment of specific GH, GT, CBM, and CE families—largely contributed by Proteobacteria—indicated enhanced degradation of polysaccharides, hemicellulose, cellulose, and cell wall components. Viral auxiliary metabolic genes encoding GH and GT classes were also markedly enriched at 270 and 330 °C, supporting the “Piggyback the Winner” strategy that strengthens host carbon metabolism. Finally, antibiotic resistance genes (ARGs) were quantified, revealing a temperature-dependent increase: 2.3-fold (HL210), 2.5-fold (HL270), and 4.6-fold (HL330) compared to controls. ARG enrichment strongly correlated with higher phenolic concentrations, with efflux- and multidrug-related genes predominating. Metagenome-assembled genomes confirmed Proteobacteria dominance, with notable enrichment of Pseudomonadaceae sp. upd67 and Enterobacter kobei in HL330-treated soils, demonstrating that intensified humification reshapes microbial metabolism while concurrently promoting ARG proliferation.

In conclusion, this study reveals that lignocellulose-derived humification exerts dual ecological effects in agricultural soils. While the transformation of crop residues enhances soil organic carbon accumulation, stimulates CAZyme-mediated carbon metabolism, and strengthens microbial adaptability, it also promotes the enrichment of antibiotic resistance genes, particularly under higher phenolic concentrations. This trade-off underscores the need for balanced residue management strategies. Optimizing composting and soil amendment practices to enhance carbon sequestration while mitigating resistance risks will be critical for sustaining soil health and minimizing long-term ecological and public health impacts.

###

References

DOI

10.48130/aee-0025-0013

Original Souce URL

https://doi.org/10.48130/aee-0025-0013

Funding information

This work was supported by the National Natural Science Foundation of China (Grant No. 22276040).

About Agricultural Ecology and Environment

Agricultural Ecology and Environment (e-ISSN 3070-0639) is a multidisciplinary platform for communicating advances in fundamental and applied research on the agroecological environment, focusing on the interactions between agroecosystems and the environment. It is dedicated to advancing the understanding of the complex interactions between agricultural practices and ecological systems. The journal aims to provide a comprehensive and cutting-edge forum for researchers, practitioners, policymakers, and stakeholders from diverse fields such as agronomy, ecology, environmental science, soil science, and sustainable development.

---

DOI

10.48130/aee-0025-0013 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Genotype identity overrides domestication status in shaping microbial diversity and functions in the rice rhizosphere and phyllosphere