{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,2]],"date-time":"2026-06-02T08:41:26Z","timestamp":1780389686847,"version":"3.54.1"},"reference-count":49,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2023,8,18]],"date-time":"2023-08-18T00:00:00Z","timestamp":1692316800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Basic Science Research Program through the National Research Foundation of Korea (NRF)","award":["NRF-2022R1I1A3069079"],"award-info":[{"award-number":["NRF-2022R1I1A3069079"]}]},{"name":"Chungnam National University Research","award":["NRF-2022R1I1A3069079"],"award-info":[{"award-number":["NRF-2022R1I1A3069079"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Studies on self-healing capsules embedded in cement composites to heal such cracks have recently been actively researched in order to improve the dimensional stability of concrete structures. In particular, capsule studies were mainly conducted to separately inject reactive healing solutions into different capsules. However, with this method, there is an important limitation in that the probability of self-healing is greatly reduced because the two healing solutions must meet and react. Therefore, we propose three-dimensional (3D) printer-based self-healing capsules with a membrane structure that allows two healing solutions to be injected into one capsule. Among many 3D printing methods, we used the fusion deposition modeling (FDM) to design, analyze, and produce new self-healing capsules, which are widely used due to their low cost, precise manufacturing, and high-speed. However, polylactic lactic acid (PLA) extruded in the FDM has low adhesion energy between stacked layers, which causes different fracture strengths depending on the direction of the applied load and the subsequent performance degradation of the capsule. Therefore, the isotropic fracture characteristics of the newly proposed four types of separated membrane capsules were analyzed using finite element method analysis. Additionally, capsules were produced using the FDM method, and the compression test was conducted by applying force in the x, y, and z directions. The isotropic fracture strength was also analyzed using the relative standard deviation (RSD) parameter. As a result, the proposed separated membrane capsule showed that the RSD of isotropic fracture strength over all directions fell to about 18% compared to other capsules.<\/jats:p>","DOI":"10.3390\/ma16165687","type":"journal-article","created":{"date-parts":[[2023,8,21]],"date-time":"2023-08-21T01:46:56Z","timestamp":1692582416000},"page":"5687","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Development of 3D-Printed Self-Healing Capsules with a Separate Membrane and Investigation of Mechanical Properties for Improving Fracture Strength"],"prefix":"10.3390","volume":"16","author":[{"given":"Taeuk","family":"Lim","sequence":"first","affiliation":[{"name":"School of Mechanical Engineering, Chungnam National University, Daejeon 34134, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0777-4327","authenticated-orcid":false,"given":"Hao","family":"Cheng","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Chungnam National University, Daejeon 34134, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jie","family":"Hu","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Chungnam National University, Daejeon 34134, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yeongjun","family":"Lee","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Chungnam National University, Daejeon 34134, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sangyou","family":"Kim","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Chungnam National University, Daejeon 34134, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jangheon","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1, Daejeon 34141, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7060-2010","authenticated-orcid":false,"given":"Wonsuk","family":"Jung","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Chungnam National University, Daejeon 34134, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,8,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"544","DOI":"10.1080\/01490451.2011.592929","article-title":"Microbially induced calcium carbonate precipitation on surface or in the bulk of soil","volume":"29","author":"Chu","year":"2012","journal-title":"Geomicrobiol. J."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"17","DOI":"10.15446\/dyna.v86n210.75343","article-title":"Mechanisms of encapsulation of bacteria in self-healing concrete","volume":"86","year":"2019","journal-title":"Dyna"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"247","DOI":"10.1016\/j.bcab.2018.11.030","article-title":"Low-cost cultivation of Sporosarcina pasteurii strain in food-grade yeast extract medium for microbially induced carbonate precipitation (MICP) application","volume":"17","author":"Omoregie","year":"2019","journal-title":"Biocatal. Agric. Biotechnol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"827","DOI":"10.1016\/j.conbuildmat.2019.07.172","article-title":"Strength and durability characteristics of concrete made by micronized biomass silica and Bacteria-Bacillus sphaericus","volume":"226","author":"Priya","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"04019002","DOI":"10.1061\/(ASCE)MT.1943-5533.0002618","article-title":"Penetrability, corrosion potential, and electrical resistivity of bacterial concrete","volume":"31","author":"Tayebani","year":"2019","journal-title":"J. Mater. Civ. Eng."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"815","DOI":"10.1016\/j.conbuildmat.2019.07.129","article-title":"Aragonite formation induced by open cultures of microbial consortia to heal cracks in concrete: Insights into healing mechanisms and crystal polymorphs","volume":"224","author":"Zhang","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1080\/19475411.2016.1152322","article-title":"Enhancement of properties of recycled coarse aggregate concrete using bacteria","volume":"7","author":"Sahoo","year":"2016","journal-title":"Int. J. Smart Nano Mater."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1016\/j.conbuildmat.2017.03.057","article-title":"Effect of bacteria on strength, permeation characteristics and micro-structure of silica fume concrete","volume":"142","author":"Siddique","year":"2017","journal-title":"Constr. Build. Mater."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"461","DOI":"10.1016\/j.conbuildmat.2015.12.112","article-title":"Influence of bacteria on compressive strength and permeation properties of concrete made with cement baghouse filter dust","volume":"106","author":"Siddique","year":"2016","journal-title":"Constr. Build. Mater."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1016\/j.conbuildmat.2016.05.146","article-title":"Properties of bacterial rice husk ash concrete","volume":"121","author":"Siddique","year":"2016","journal-title":"Constr. Build. Mater."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"567","DOI":"10.1007\/s10295-011-1037-1","article-title":"Diatomaceous earth as a protective vehicle for bacteria applied for self-healing concrete","volume":"39","author":"Wang","year":"2012","journal-title":"J. Ind. Microbiol. Biotechnol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.conbuildmat.2013.06.061","article-title":"Biogenic treatment improves the durability and remediates the cracks of concrete structures","volume":"48","author":"Achal","year":"2013","journal-title":"Constr. Build. Mater."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1016\/j.conbuildmat.2017.04.003","article-title":"Effects of bacterial remediation on compressive strength, water absorption, and chloride permeability of lightweight aggregate concrete","volume":"145","author":"Balam","year":"2017","journal-title":"Constr. Build. Mater."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1016\/j.ecoleng.2008.12.036","article-title":"Application of bacteria as self-healing agent for the development of sustainable concrete","volume":"36","author":"Jonkers","year":"2010","journal-title":"Ecol. Eng."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1016\/j.biosystemseng.2015.03.008","article-title":"Influence of biodeposition treatment on concrete durability in a sulphate environment","volume":"133","author":"Nosouhian","year":"2015","journal-title":"Biosyst. Eng."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Hammad, N., Elnemr, A., and Shaaban, I.G. (2023). State-of-the-Art Report: The Self-Healing Capability of Alkali-Activated Slag (AAS) Concrete. Materials, 16.","DOI":"10.3390\/ma16124394"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"669","DOI":"10.1016\/j.conbuildmat.2019.02.178","article-title":"First UK field application and performance of microcapsule-based self-healing concrete","volume":"208","author":"Litina","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1016\/j.cemconcomp.2017.09.012","article-title":"Chemical self-healing system with novel microcapsules for corrosion inhibition of rebar in concrete","volume":"85","author":"Dong","year":"2018","journal-title":"Cem. Concr. Compos."},{"key":"ref_19","first-page":"441","article-title":"Fundamental study on development of intelligent concrete characterized by self-healing capability for strength","volume":"22","author":"Mihashi","year":"2000","journal-title":"Trans. Jpn. Concr. Inst."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"608","DOI":"10.1016\/j.conbuildmat.2015.12.140","article-title":"Self-healing features in cementitious material with urea\u2013formaldehyde\/epoxy microcapsules","volume":"106","author":"Dong","year":"2016","journal-title":"Constr. Build. Mater."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1163\/15685610360472457","article-title":"A comparison of internal self-repair with resin injection in repair of concrete","volume":"17","author":"Dry","year":"2003","journal-title":"J. Adhes. Sci. Technol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"577","DOI":"10.1016\/j.conbuildmat.2016.06.119","article-title":"The effect of varying volume fraction of microcapsules on fresh, mechanical and self-healing properties of mortars","volume":"122","author":"Kanellopoulos","year":"2016","journal-title":"Constr. Build. Mater."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"4064","DOI":"10.3390\/ma6094064","article-title":"Experimental study on cementitious composites embedded with organic microcapsules","volume":"6","author":"Wang","year":"2013","journal-title":"Materials"},{"key":"ref_24","first-page":"13","article-title":"Application of encapsulated lightweight aggregate impregnated with sodium monofluorophosphate as a self-healing agent in blast furnace slag mortar","volume":"56","author":"Sisomphon","year":"2011","journal-title":"Heron"},{"key":"ref_25","first-page":"28","article-title":"Experimental research on the self-healing performance of micro-cracks in concrete bridge","volume":"250","author":"Sun","year":"2011","journal-title":"Adv. Mater. Res."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"497","DOI":"10.1016\/j.cemconcomp.2011.01.004","article-title":"Self-healing efficiency of cementitious materials containing tubular capsules filled with healing agent","volume":"33","author":"Jacobs","year":"2011","journal-title":"Cem. Concr. Compos."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"763","DOI":"10.1016\/j.cemconcomp.2011.03.012","article-title":"Quantification of crack-healing in novel bacteria-based self-healing concrete","volume":"33","author":"Wiktor","year":"2011","journal-title":"Cem. Concr. Compos."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"506","DOI":"10.1016\/j.cemconcomp.2011.01.010","article-title":"A self-healing cementitious composite using oil core\/silica gel shell microcapsules","volume":"33","author":"Yang","year":"2011","journal-title":"Cem. Concr. Compos."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"144","DOI":"10.1021\/la203088u","article-title":"Designer polymer-based microcapsules made using microfluidics","volume":"28","author":"Chen","year":"2012","journal-title":"Langmuir"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Wang, X., Sun, P., Han, N., and Xing, F. (2017). Experimental study on mechanical properties and porosity of organic microcapsules based self-healing cementitious composite. Materials, 10.","DOI":"10.3390\/ma10010020"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Lim, T., Cheng, H., Song, W., Lee, J., Kim, S., and Jung, W. (2021). Simulated and Experimental Investigation of Mechanical Properties for Improving Isotropic Fracture Strength of 3D-Printed Capsules. Materials, 14.","DOI":"10.3390\/ma14164677"},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Choi, S.-J., Kim, J.-H., Jeong, H., Lee, J.-S., Lim, T.-U., Ko, H.M., Kim, S.H., and Jung, W. (2021). Simulated and Experimental Investigation of the Mechanical Properties and Solubility of 3D-Printed Capsules for Self-Healing Cement Composites. Materials, 14.","DOI":"10.3390\/ma14164578"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Xu, Y., Zhang, F., Zhai, W., Cheng, S., Li, J., and Wang, Y. (2022). Unraveling of Advances in 3D-Printed Polymer-Based Bone Scaffolds. Polymers, 14.","DOI":"10.3390\/polym14030566"},{"key":"ref_34","first-page":"198","article-title":"Development of a Large-scale multi-extrusion FDM printer, and its challenges","volume":"6","author":"Ali","year":"2022","journal-title":"Int. J. Lightweight Mater. Manuf."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"109531","DOI":"10.1016\/j.compscitech.2022.109531","article-title":"One-step fabrication of highly sensitive pressure sensor by all FDM printing","volume":"226","author":"Zhang","year":"2022","journal-title":"Compos. Sci. Technol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"102958","DOI":"10.1016\/j.jwpe.2022.102958","article-title":"3D printed nanofiltration membrane technology for waste water distillation","volume":"49","author":"Khan","year":"2022","journal-title":"J. Water Process Eng."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"7227","DOI":"10.1007\/s10853-023-08460-0","article-title":"4D printing of PLA-TPU blends: Effect of PLA concentration, loading mode, and programming temperature on the shape memory effect","volume":"58","author":"Rahmatabadi","year":"2023","journal-title":"J. Mater. Sci."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"3741","DOI":"10.1016\/j.jmrt.2019.06.034","article-title":"Mechanical characteristics of wood, ceramic, metal and carbon fiber-based PLA composites fabricated by FDM","volume":"8","author":"Liu","year":"2019","journal-title":"J. Mater. Res. Technol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1183","DOI":"10.1007\/s11837-015-1367-y","article-title":"Mechanical property optimization of FDM PLA in shear with multiple objectives","volume":"67","author":"Torres","year":"2015","journal-title":"JOM"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"108089","DOI":"10.1016\/j.matdes.2019.108089","article-title":"Novel mechanical models of tensile strength and elastic property of FDM AM PLA materials: Experimental and theoretical analyses","volume":"181","author":"Zhao","year":"2019","journal-title":"Mater. Des."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"31850","DOI":"10.1016\/j.ceramint.2022.07.117","article-title":"Developing a novel technique for the fabrication of PLA-graphite composite filaments using FDM 3D printing process","volume":"48","author":"Zerankeshi","year":"2022","journal-title":"Ceram. Int."},{"key":"ref_42","first-page":"197","article-title":"Reducing print time while minimizing loss in mechanical properties in consumer FDM parts","volume":"5","author":"Le","year":"2022","journal-title":"Int. J. Lightweight Mater. Manuf."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Nakonieczny, D.S., Kern, F., Dufner, L., Dubiel, A., Antonowicz, M., and Matus, K. (2021). Effect of Calcination Temperature on the Phase Composition, Morphology, and Thermal Properties of ZrO2 and Al2O3 Modified with APTES (3-aminopropyltriethoxysilane). Materials, 14.","DOI":"10.3390\/ma14216651"},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Nakonieczny, D.S., Kern, F., Dufner, L., Antonowicz, M., and Matus, K. (2021). Alumina and zirconia-reinforced polyamide PA-12 composites for biomedical additive manufacturing. Materials, 14.","DOI":"10.3390\/ma14206201"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1016\/j.progpolymsci.2008.10.001","article-title":"Melt\u2013solid polycondensation of lactic acid and its biodegradability","volume":"34","author":"Maharana","year":"2009","journal-title":"Prog. Polym. Sci."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"11898","DOI":"10.1038\/s41598-017-11950-2","article-title":"Flow of tunable elastic microcapsules through constrictions","volume":"7","author":"Mehl","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1115\/1.3422928","article-title":"On the contact problem of an inflated spherical nonlinear membrane","volume":"40","author":"Feng","year":"1973","journal-title":"J. Appl. Mech. Mar."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"725","DOI":"10.1007\/s11340-006-9659-3","article-title":"Mechanical properties of microcapsules used in a self-healing polymer","volume":"46","author":"Keller","year":"2006","journal-title":"Exp. Mech."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1016\/j.jcis.2006.04.062","article-title":"Identification of the elastic properties of an artificial capsule membrane with the compression test: Effect of thickness","volume":"301","author":"Rachik","year":"2006","journal-title":"J. Colloid Interface Sci."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/16\/16\/5687\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T20:37:16Z","timestamp":1760128636000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/16\/16\/5687"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,8,18]]},"references-count":49,"journal-issue":{"issue":"16","published-online":{"date-parts":[[2023,8]]}},"alternative-id":["ma16165687"],"URL":"https:\/\/doi.org\/10.3390\/ma16165687","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,8,18]]}}}