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Autonomous self-burying seed carriers for aerial seeding

Abstract

Aerial seeding can quickly cover large and physically inaccessible areas1 to improve soil quality and scavenge residual nitrogen in agriculture2, and for postfire reforestation3,4,5 and wildland restoration6,7. However, it suffers from low germination rates, due to the direct exposure of unburied seeds to harsh sunlight, wind and granivorous birds, as well as undesirable air humidity and temperature1,8,9. Here, inspired by Erodium seeds10,11,12,13,14, we design and fabricate self-drilling seed carriers, turning wood veneer into highly stiff (about 4.9 GPa when dry, and about 1.3 GPa when wet) and hygromorphic bending or coiling actuators with an extremely large bending curvature (1,854 m−1), 45 times larger than the values in the literature15,16,17,18. Our three-tailed carrier has an 80% drilling success rate on flat land after two triggering cycles, due to the beneficial resting angle (25°–30°) of its tail anchoring, whereas the natural Erodium seed’s success rate is 0%. Our carriers can carry payloads of various sizes and contents including biofertilizers and plant seeds as large as those of whitebark pine, which are about 11 mm in length and about 72 mg. We compare data from experiments and numerical simulation to elucidate the curvature transformation and actuation mechanisms to guide the design and optimization of the seed carriers. Our system will improve the effectiveness of aerial seeding to relieve agricultural and environmental stresses, and has potential applications in energy harvesting, soft robotics and sustainable buildings.

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Fig. 1: Bioinspired design of the autonomous self-drilling seed carrier.
Fig. 2: The curvature formation mechanism and hygromorphic actuation.
Fig. 3: Geometrical parameters of the seed carrier design.
Fig. 4: Tailored designs of self-drilling carriers.

Data availability

Data generated and analysed during the study is available at https://doi.org/10.5281/zenodo.7057562. Digital models, processing protocols and datasets are available on request from L.Y.

Code availability

Code used for the finite-element analysis to simulate coil extension and drilling is available at https://doi.org/10.5281/zenodo.7263943. Further information on code and models used is available on request from T.Z.

References

  1. Fisher, K. A., Momen, B. & Kratochvil, R. J. Is broadcasting seed an effective winter cover crop planting method? Agron. J. 103, 472–478 (2011).

    Article  Google Scholar 

  2. Ball, B. C. Cereal production with broadcast seed and reduced tillage: a review of recent experimental and farming experience. J. Agric. Eng. Res. 35, 71–95 (1986).

    Article  Google Scholar 

  3. Kelly, L. T. et al. Fire and biodiversity in the Anthropocene. Science 370, eabb0355 (2020).

    Article  CAS  PubMed  Google Scholar 

  4. Keane, R. E. Managing wildfire for whitebark pine ecosystem restoration in western North America. Forests 9, 648 (2018).

    Article  Google Scholar 

  5. Xiao, X. et al. Aerial seeding: an effective forest restoration method in highly degraded forest landscapes of sub-tropic regions. Forests 6, 1748–1762 (2015).

    Article  Google Scholar 

  6. Monsen, S. B., Stevens, R. & Shaw, N. L. Restoring Western Ranges and Wildlands, vol. 1. (US Department of Agriculture, Forest Service, Rocky Mountain Research Station, 2004).

  7. Ranwell, D. S. in Geology and Engineering (Ed. Cronin, L. E.) 471–483 (Elsevier, 1975).

  8. Collins, B. A. & Fowler, D. B. A comparison of aerial and conventional methods for seeding winter wheat. Soils and Crops Workshop (University of Saskatchewan, 1989).

  9. Keisling, T. C., Dillon, C. R., Oxner, M. D. & Counce, P. A. An economic and agronomic evaluation of selected wheat planting methods in Arkansas. In Proc. Southern Conservation Tillage Conference 156–158 (1997).

  10. Stamp, N. E. Self-burial behaviour of Erodium cicutarium seeds. J. Ecol. 72, 611–620 (1984).

    Article  Google Scholar 

  11. Ha, J. et al. Hygroresponsive coiling of seed awns and soft actuators. Extreme Mech. Lett. 38, 100746 (2020).

    Article  Google Scholar 

  12. Almeida, A. P. C. et al. Reversible water driven chirality inversion in cellulose-based helices isolated from Erodium awns. Soft Matter 15, 2838–2847 (2019).

    Article  ADS  CAS  PubMed  Google Scholar 

  13. Abraham, Y. et al. Tilted cellulose arrangement as a novel mechanism for hygroscopic coiling in the stork’s bill awn. J. R. Soc. Interface 9, 640–647 (2012).

    Article  PubMed  Google Scholar 

  14. Evangelista, D., Hotton, S. & Dumais, J. The mechanics of explosive dispersal and self-burial in the seeds of the filaree, Erodium cicutarium (Geraniaceae). J. Exp. Biol. 214, 521–529 (2011).

    Article  PubMed  Google Scholar 

  15. Rüggeberg, M. & Burgert, I. Bio-inspired wooden actuators for large scale applications. PLoS ONE 10, e0120718 (2015).

    Article  PubMed  PubMed Central  Google Scholar 

  16. Grönquist, P. et al. Analysis of hygroscopic self-shaping wood at large scale for curved mass timber structures. Sci. Adv. 5, eaax1311 (2019).

    Article  ADS  PubMed  PubMed Central  Google Scholar 

  17. Holstov, A., Bridgens, B. & Farmer, G. Hygromorphic materials for sustainable responsive architecture. Constr. Build. Mater. 98, 570–582 (2015).

    Article  Google Scholar 

  18. Krieg, O. D. in Advancing Wood Architecture: a Computational Approach (eds. Achim, M. et al.) 16 (Routledge, Taylor & Francis, 2016).

  19. Cavanagh, A. M., Morgan, J. W. & Godfree, R. C. Awn morphology influences dispersal, microsite selection and burial of Australian native grass diaspores. Front. Ecol. Evol. 8, 581967 (2020).

    Article  Google Scholar 

  20. Tothill, J. C. Soil temperatures and seed burial in relation to the performance of Heteropogon contortus and Themeda australis in burnt native woodland pastures in eastern Queensland. Aust. J. Bot. 17, 269–275 (1969).

    Article  Google Scholar 

  21. Rice, K. J. Responses of Erodium to varying microsites: the role of germination cueing. Ecology 66, 1651–1657 (1985).

    Article  Google Scholar 

  22. Garnier, L. K. M. & Dajoz, I. Evolutionary significance of awn length variation in a clonal grass of fire-prone savannas. Ecology 82, 1720–1733 (2001).

    Article  Google Scholar 

  23. Keane, R. E. & Parsons, R. A. Management Guide to Ecosystem Restoration Treatments: Whitebark Pine Forests of the Northern Rocky Mountains, U.S.A. 133 (US Department of Agriculture, Forest Service, Rocky Mountain Research Station, 2010).

  24. Luo, D., Gu, J., Qin, F., Wang, G. & Yao, L. E-seed: shape-changing interfaces that self drill. In Proc. 33rd Annual ACM Symposium on User Interface Software and Technology 45–57 (Association for Computing Machinery, 2020).

  25. Igiehon, N. O. & Babalola, O. O. Biofertilizers and sustainable agriculture: exploring arbuscular mycorrhizal fungi. Appl. Microbiol. Biotechnol. 101, 4871–4881 (2017).

    Article  CAS  PubMed  Google Scholar 

  26. Jung, W., Kim, W. & Kim, H.-Y. Self-burial mechanics of hygroscopically responsive awns. Integr. Comp. Biol. 54, 1034–1042 (2014).

    Article  CAS  PubMed  Google Scholar 

  27. Jung, W., Choi, S. M., Kim, W. & Kim, H.-Y. Reduction of granular drag inspired by self-burrowing rotary seeds. Phys. Fluids 29, 041702 (2017).

    Article  ADS  Google Scholar 

  28. Agnarsson, I., Dhinojwala, A., Sahni, V. & Blackledge, T. A. Spider silk as a novel high performance biomimetic muscle driven by humidity. J. Exp. Biol. 212, 1990–1994 (2009).

    Article  PubMed  Google Scholar 

  29. Chen, X., Mahadevan, L., Driks, A. & Sahin, O. Bacillus spores as building blocks for stimuli-responsive materials and nanogenerators. Nat. Nanotechnol. 9, 137–141 (2014).

    Article  ADS  CAS  PubMed  Google Scholar 

  30. Park, Y. et al. β‐Sheet nanocrystals dictate water responsiveness of Bombyx mori silk. Macromol. Rapid Commun. 41, 1900612 (2020).

    Article  CAS  Google Scholar 

  31. Zhao, Z. et al. Digital printing of shape-morphing natural materials. Proc. Natl Acad. Sci. USA 118, e2113715118 (2021).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  32. Shintake, J., Sonar, H., Piskarev, E., Paik, J. & Floreano, D. Soft pneumatic gelatin actuator for edible robotics. In 2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) 6221–6226 (IEEE, 2017).

  33. He, Q., Huang, Y. & Wang, S. Hofmeister effect-assisted one step fabrication of ductile and strong gelatin hydrogels. Adv. Funct. Mater. 28, 1705069 (2018).

    Article  Google Scholar 

  34. Baumgartner, M. et al. Resilient yet entirely degradable gelatin-based biogels for soft robots and electronics. Nat. Mater. 19, 1102–1109 (2020).

    Article  ADS  CAS  PubMed  Google Scholar 

  35. Zhao, D. et al. High-strength and high-toughness double-cross-linked cellulose hydrogels: a new strategy using sequential chemical and physical cross-linking. Adv. Funct. Mater. 26, 6279–6287 (2016).

    Article  CAS  Google Scholar 

  36. Song, J. et al. Processing bulk natural wood into a high-performance structural material. Nature 554, 224–228 (2018).

    Article  ADS  CAS  PubMed  Google Scholar 

  37. Frey, M. et al. Delignified and densified cellulose bulk materials with excellent tensile properties for sustainable engineering. ACS Appl. Mater. Interfaces 10, 5030–5037 (2018).

    Article  CAS  PubMed  Google Scholar 

  38. Frey, M. et al. Tunable wood by reversible interlocking and bioinspired mechanical gradients. Adv. Sci. 6, 1802190 (2019).

    Article  Google Scholar 

  39. Xiao, S. et al. Lightweight, strong, moldable wood via cell wall engineering as a sustainable structural material. Science 374, 465–471 (2021).

    Article  ADS  CAS  PubMed  Google Scholar 

  40. Holmberg, S., Persson, K. & Petersson, H. Nonlinear mechanical behaviour and analysis of wood and fibre materials. Comput. Struct. 72, 459–480 (1999).

    Article  MATH  Google Scholar 

  41. Báder, M., Németh, R. & Konnerth, J. Micromechanical properties of longitudinally compressed wood. Eur. J. Wood Wood Prod. 77, 341–351 (2019).

    Article  Google Scholar 

  42. Donaldson, L. Microfibril angle: measurement, variation and relationships – a review. IAWA J. 29, 345–386 (2008).

    Article  Google Scholar 

  43. Goodrich-Blair, H. They’ve got a ticket to ride: Xenorhabdus nematophilaSteinernema carpocapsae symbiosis. Curr. Opin. Microbiol. 10, 225–230 (2007).

    Article  CAS  PubMed  Google Scholar 

  44. Gaugler, R. & Boush, G. M. Effects of ultraviolet radiation and sunlight on the entomogenous nematode, Neoaplectana carpocapsae. J. Invertebr. Pathol. 32, 291–296 (1978).

    Article  Google Scholar 

  45. Chen, X. et al. Scaling up nanoscale water-driven energy conversion into evaporation-driven engines and generators. Nat. Commun. 6, 7346 (2015).

    Article  ADS  CAS  PubMed  Google Scholar 

  46. Park, Y. & Chen, X. Water-responsive materials for sustainable energy applications. J. Mater. Chem. A 8, 15227–15244 (2020).

    Article  CAS  Google Scholar 

  47. Shin, B. et al. Hygrobot: a self-locomotive ratcheted actuator powered by environmental humidity. Sci. Robot. 3, eaar2629 (2018).

    Article  PubMed  Google Scholar 

  48. Wen, M.-Y., Kang, C.-W. & Park, H.-J. Impregnation and mechanical properties of three softwoods treated with a new fire retardant chemical. J. Wood Sci. 60, 367–375 (2014).

    Article  CAS  Google Scholar 

  49. Stamp, N. E. Seed dispersal of four sympatric grassland annual species of Erodium. J. Ecol. 77, 1005 (1989).

    Article  Google Scholar 

  50. Freckman, D. W. & Virginia, R. A. Low-diversity Antarctic soil nematode communities: distribution and response to disturbance. Ecology 78, 363–369 (1997).

    Article  Google Scholar 

  51. Yang, N., Li, T. & Zhang, L. A two-dimensional lattice model for simulating the failure and fracture behavior of wood. Wood Sci. Technol. 54, 63–87 (2020).

    Article  CAS  Google Scholar 

  52. Reiterer, A. & Stanzl-Tschegg, S. E. Compressive behaviour of softwood under uniaxial loading at different orientations to the grain. Mech. Mater. 33, 705–715 (2001).

    Article  Google Scholar 

  53. Hanhijärvi, A. Advances in the knowledge of the influence of moisture changes on the long-term mechanical performance of timber structures. Mater. Struct. 33, 43 (2000).

    Article  Google Scholar 

  54. Fortino, S., Mirianon, F. & Toratti, T. A 3D moisture-stress FEM analysis for time dependent problems in timber structures. Mech. Time Depend. Mater. 13, 333 (2009).

    Article  ADS  Google Scholar 

  55. Lunni, D., Cianchetti, M., Filippeschi, C., Sinibaldi, E. & Mazzolai, B. Plant‐inspired soft bistable structures based on hygroscopic electrospun nanofibers. Adv. Mater. Interfaces 7, 1901310 (2020).

    Article  CAS  Google Scholar 

  56. Krüger, F. et al. Development of a material design space for 4D-printed bio-inspired hygroscopically actuated bilayer structures with unequal effective layer widths. Biomimetics 6, 58 (2021).

    Article  PubMed  PubMed Central  Google Scholar 

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Acknowledgements

We thank C. Y. Wei for processing suggestions, E. Sharon for mechanism discussions, and L. B. Hu, J. Z. Gu and J. Forman for helpful insights. We also thank J. Y. Zhu and N. Z. Plaza from the US Department of Agriculture Forest Products Laboratory for discussions and characterization through X-ray diffraction. We acknowledge funding support from the US National Science Foundation, including IIS-CAREER-1847149 (L.Y.), CMMI-2020476 (T.Z.) and the Future Eco Manufacturing Research Grant, no. CMMI 2037097 (S.Y.). Simulations were carried out at the Triton Shared Computing Cluster at the San Diego Supercomputer Center and the Expanse cluster (TG-MSS170004, T.Z.) in the Extreme Science and Engineering Discovery Environment. We also acknowledge the use of the Materials Characterization Facility at Carnegie Mellon University (MCF-677785, L.Y.), the National Natural Science Foundation of China (62002321, G.W.) and a gift to Carnegie Mellon University (L.Y.) from Accenture Labs.

Author information

Authors and Affiliations

Authors

Contributions

L.Y. and D.L. conceived the initial concept. A.M. and A.D. conceived two application contexts. L.Y., T.Z., S.Y. and G.W. supervised the project. L.Y., D.L., T.Z. and S.Y. wrote the manuscript. D.L., L.Y. and G.W. carried out fabrication and peak force measurements. D.L., L.Y., G.W., J.L., Y.Y., Y.T. and L.S. carried out drilling and germination tests. D.L., L.Y. and Y.Y. carried out bending angle and coil pitch measurements. D.L., L.Y. and D.K.P. carried out scanning electron microscopy and micrograph analysis. D.K.P. and L.Y. conducted tensile tests. T.Z. and L.Y. carried out curvature analysis. T.Z. carried out mechanical modelling and simulation. S.Y., T.Z. and L.Y. provided scientific and experimental advice. L.Y. and D.L. created the videos.

Corresponding authors

Correspondence to Guanyun Wang, Shu Yang, Teng Zhang or Lining Yao.

Ethics declarations

Competing interests

A US patent application (application no. 17/718,232) on the methods and devices for the biomimetic composite has been filed by Carnegie Mellon University (assignors: L.Y., G.W., J. Gu, D.L. and F. Qin.). The other authors declare no competing interests.

Peer review

Peer review information

Nature thanks Barbara Mazzolai, Naomi Nakayama and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

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Extended data figures and tables

Extended Data Fig. 1 SEM images of partially delignified wood veneer.

a, Chemically washed and moulded wood veneer (0.5 mm thick, 0.8 mm mandrel diameter). Wrinkled cell walls are caused by mechanical moulding on the longitudinal cells on the inner side. The outer side cells show no obvious signs of deformation. b, The chemically washed but not moulded wood veneer, showing uniform cell structure throughout the sample.

Extended Data Fig. 2 Performance of the engineered moisture-driven actuators.

a, Reversible curvature changes of a bending actuator during three actuation cycles. b, Reversible actuation of a moulded coiling actuator with seven coils in three consecutive hydration-dehydration cycles, showing the angular changes relative to the initial position of the top end of the helix (θ-θdry). Both actuators are 3 mm in width and 0.5 mm in thickness, moulded with a mandrel, with a 0.8 mm diameter. The length is 3 mm in (a) and 40 mm in (b).

Extended Data Fig. 3 Design of a remote-controlled device that can be attached to a drone to carry and deploy seeds.

a, Photograph of the customized seed deployment mechanism attached to a drone. bd, Top view of the device with a sliding cover to prevent turbulence caused by the wings of the drone from affecting the deployment. ef, Bottom view of the device, with a magnetic double-side door that can be opened with a remote-controlled pulling mechanism, shown in (g). hj, A field test of the aerial delivery with examination of the landing pose of the seed carriers. kl, a portion of the seed carriers for the aerial delivery test. The tails are dyed with bright colors for easy identification. Scale bar: 10 mm.

Extended Data Fig. 4 Photos of the fabrication and assembly of the seed carrier prototypes.

af, The process of turning a white oak log into a wood veneer with a specified thickness and fiber orientation. gh, The process of laser cutting, chemical washing and manual moulding of the wood strips. i, The chemical washing process. jn, The mechanical moulding process. o-q, Adding two additional tails for three-tailed seed carriers. rw, The tip manufacturing process adapted from the literature24 with additional seeds embedding. x, The process of moulding a double-coiled body. Scale bar is 10 mm unless otherwise specified.

Extended Data Fig. 5 Comparison of the self-drilling depth between a double-coiled and a single-coiled seed carrier.

ab, Photographs of four cycles of a double-coiled seed carrier (a) and a single-coiled seed carrier (b) at each hydration and dehydration state.

Extended Data Fig. 6 Tracking of the living nematodes extracted from the soil.

a, Representative images of nematodes extracted from the soil (Methods). b, The total number of living nematodes identified in the soil samples. Data are means ± s.d. n = 3 soil samples each day.

Extended Data Fig. 7 Selective field drilling and germination test results (more details in Supplementary Table 5).

a, Drilling test 1 from Table S5, with 22 three-tailed seed carriers under natural conditions for two consecutive days. b, A rain-anchored seed continues to drill after the sun emerges, as shown in drilling test 3 of Table S5. c, Established seed carriers tend to germinate more easily than non-established seed carriers after five days with four periods of rain. The established and exposed seeds had a 100% and 19% germination rate, respectively, in drilling test 1 of Supplementary Table 5.

Extended Data Fig. 8 Optimizing the material choice and processing method.

a, Comparison of the mouldability and actuation range of bending actuators made of different types of wood. The wood strip is ~0.5 mm thick and the moulding diameter is 0.8 mm. Data are means ± s.d. n = 3 samples for each type of wood. b, Comparison of the mouldability of the seed body made of various types of wood. The wood strip is ~0.5 mm thick. c, Effect of the chemical washing durations on the curvature changes. For both (a) and (c), data are means ± s.d. n = 3 with a thickness of ~0.5 mm, length of ~3 mm and width of ~3 mm, moulded with a mandrel with a 0.8 mm diameter. d, Moulding quality comparison on wood veneer of different thickness, moulded on mandrels of different diameters, with a washing duration of 10 min.

Extended Data Fig. 9 Experiments and simulations for seed carrier drilling on a surface that is hard and smooth.

a, Simulation (top) and experimental (bottom) snapshots of the drilling process of the single-tailed design seed carrier. b, Simulation (top) and experimental (bottom) snapshots of the drilling process of the three-tailed design seed carrier.

Supplementary information

Supplementary Information

This file contains Supplementary Tables 1–5, Notes 1–12 including Figs. 1–26, and References.

Reporting Summary

Supplementary Video 1

The natural Erodium seed has an inevitable crevice-searching phase that can negatively impact the drilling efficiency especially in the case of relatively flat land.

Supplementary Video 2

Dropping test of both natural and engineered seed carriers. Compared to Erodium seeds thath have an 80% chance of landing flat, this three-tailed carrier has a 90% chance of landing with a guaranteed angle between its body and the ground to increase the drilling success.

Supplementary Video 3

Comparing the self-drilling success of the engineered three-tailed seed carrier and the natural single-tailed Erodium seed.

Supplementary Video 4

Experiment and finite-element simulation of the self-drilling processes of both three-tailed and single-tailed designs. The three-tailed design generates a larger force, as multiple tail tips and bodies can generate effective torques simultaneously.

Supplementary Video 5

Self-drilling processes of three seed carrier design variations, including three-tailed, double-coiled and large-sized systems, tailored to different use cases. The tests were conducted in an indoor controlled environment.

Supplementary Video 6

Fabrication process of the seed carriers.

Supplementary Video 7

Germination experiment using the three-tailed seed carrier, with embedded symbiotic cherry belle radish seeds and beneficial fungi, captured for a duration of 190 h.

Supplementary Video 8

Living nematodes captured in the soil after 9 days of seed burial.

Supplementary Video 9

Successful self-drilling and germination under natural conditions outdoors for 7 continuous days, with 2 periods of intermittent light rain on the first day and 1 thunderstorm and heavy rain, which lasted for more than 6 h on the second day.

Peer Review File

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Luo, D., Maheshwari, A., Danielescu, A. et al. Autonomous self-burying seed carriers for aerial seeding. Nature 614, 463–470 (2023). https://doi.org/10.1038/s41586-022-05656-3

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