Self-healing Technology Research Articles

Wearable Sensor for Continuous Sweat Biomarker Monitoring

In recent years, wearable sensors have enabled the unique mode of real-time and noninvasive monitoring to develop rapidly in medical care, sports, and other fields. Sweat contains a wide range of biomarkers such as metabolites, electrolytes, and various hormones. Combined with wearable technology, sweat can reflect human fatigue, disease, mental stress, dehydration, and so on. This paper comprehensively describes the analysis of sweat components such as glucose, lactic acid, electrolytes, pH, cortisol, vitamins, ethanol, and drugs by wearable sensing technology, and the application of sweat wearable devices in glasses, patches, fabrics, tattoos, and paper. The development trend of sweat wearable devices is prospected. It is believed that if the sweat collection, air permeability, biocompatibility, sensing array construction, continuous monitoring, self-healing technology, power consumption, real-time data transmission, specific recognition, and other problems of the wearable sweat sensor are solved, we can provide the wearer with important information about their health level in the true sense.

Application of Carrier Materials in Self-Healing Cement-Based Materials Based on Microbial-Induced Mineralization

Microbially induced calcium carbonate precipitation (MICP) technology has attracted widespread research attention owing to its application in crack healing for cement-based materials in an intelligent and environmentally friendly manner. However, the high internal alkalinity, low nutrient content, and dense structure of cement-based materials have restricted its application in self-healing cement-based materials. Various carrier materials have been widely used for the immobilization of microorganisms in recent years. Carrier materials have significantly increased the ability of microorganisms to withstand extreme conditions (high temperature, high alkali, etc.) and have provided new ideas for the compatibility of microorganisms with cement-based materials. In this study, the basic principles of microbial self-healing technology in cement-based materials and microbial immobilization methods and the influencing factors are introduced, followed by a review of the research progress and application effects of different types of carrier materials, such as aggregate, low-alkali cementitious materials, organic materials, and microcapsules. Finally, the current problems and promising development directions of microbial carrier materials are summarized to provide useful references for the future development of microbial carriers and self-healing cement-based materials.

A review on current direct and indirect testing methods as high-effective techniques in the evaluation of self-healing ability in concrete

As it has been using more than 100 years, concrete is a high compressive strength construction material and relatively easy to maintain and manage for buildings and infrastructures. However, with the increasing technical requirements of society for new constructions, various technologies have been developed to improve the strength, performance, and durability of concrete and overcome weaknesses, including the cracking phenomenon. The crack handling of concrete structures is a research hotspot and has caused long-term problems for the development of the engineering community. Currently, research on the world's self-healing concrete technology has been conducted in various ways. Also, promising progress has been made in different research approaches, but most are still in theoretical feasibility and laboratory-scale. Although there have been many reviews or mini-review papers published, aggregation, refinement, and criticism have never been redundant in light of the continued increase in the number of new publications. This paper has summarized the experimental research methods and results of different types of self-healing concrete in recent years and expounded the mechanism of its action, especially in the trend of using microorganisms for sustainable development. We also point out the outstanding issues and limitations in the studies and propose solutions.

Self-healing of electrical tree damage of polyethylene/microcapsules insulation composite material

During the use of polyethylene (PE) cable in power systems, electrical tree damages can inevitably occur inside the insulation materials, causing partial discharges and threatening the safety of the power supply. It is difficult to detect the micro damages inside the materials by existing technology, and replacing cables creates a lot of solid waste. The microcapsule self-healing technology derived from bionics can automatically detect and heal micro damages inside the material in time, avoiding accidents and saving resources. In this paper, the self-healing abilities and mechanism of the PE/microcapsule composite materials to the electrical tree damage are studied by means of experiments and simulation. PE/microcapsule composite materials are prepared, and the composite material with 1 wt% microcapsule is demonstrated to have better insulation strength. Microcapsules can attract the development of electric trees and limit their size, while the electrical tree can trigger the self-healing behavior of microcapsules in time. The self-healing behavior can effectively heal the electrical tree branch channel, restore breakdown strength and polarization current, and reverse the deterioration process of the material. Molecular dynamics (MD) simulation confirms that there is good chemical compatibility between the healing product and PE matrix, ensuring a good self-healing effect.

The Application of the Modified Prim’s Algorithm to Restore the Power System Using Renewable Energy Sources

The recent trends in the development of power systems are focused on the Self-Healing Grid technology fusing renewable energy sources. In the event of a failure of the power system, automated distribution grids should continue to supply energy to consumers. Unfortunately, there are currently a limited number of algorithms for rebuilding a power system with renewable energy sources. This problem is possible to solve by implementing restoration algorithms based on graph theory. This article presents the new modification of Prim’s algorithm, which has been adapted to operate on a power grid containing several power sources, including renewable energy sources. This solution is unique because Prim’s algorithm is ultimately dedicated to single-source graph topologies, while the proposed solution is adapted to multi-source topologies. In the algorithm, the power system is modeled by the adjacency matrices. The adjacency matrixes for the considered undirected graphs are symmetric. The novel logic is based on the original method of determining weights depending on active power, reactive power and active power losses. The developed solution was verified by performing a simulation on a test model of the distribution grid powered by a renewable energy source. The control logic concept was compared with the reference algorithms, which were chosen from the ideas representing available approaches based on graph theory present in the scientific publications. The conducted research confirmed the effectiveness and validity of the novel restoration strategy. The presented algorithm may be applied as a restoration logic dedicated to power distribution systems.

Technology Focus: Cementing and Zonal Isolation (May 2022)

Over the past year, the number of cementing and zonal-isolation papers was much lower than usual because of the cancellation and postponement of several conferences. The overall impact, however, was mitigated by the transformation of several conferences to online events. I attended one virtual event and was pleasantly surprised with the value of the technical discussions that immediately followed each paper presentation and the willingness of authors to follow up on discussions after the conference. The development of new technology can take a significant amount of time and resources, and full worldwide introduction may take many years, giving rise to a commercial risk for the technology developer. One paper published last year described the first case history of self-healing cement technology in one geographical area more than 10 years after the publication of the first field application of the technology. In the October 2021 issue of JPT, SPE President Kamel Ben-Naceur discussed the importance of collaboration in solving technical problems quickly and efficiently. Three of the papers selected in this section are from collaborations between multiple companies pooling their expertise and resources to develop solutions for complex problems that could not be addressed efficiently by individual companies. Papers SPE 204015 and SPE 208782 issue from consortia whose goals are to improve the efficiency and reliability of plugging-and-abandonment operations. Paper SPE 204103 is a jointly funded collaboration evaluating CO2-resistant cement with a new experimental methodology to accelerate chemical interactions between the cement and CO2, thus shortening the validation time. The commercial risks associated with the incremental developments of existing technology can be acceptable more readily to individual companies, although this does not mean that efficient internal teamwork is not required. The three other papers selected are all supported and authored by individual companies, but each is a collaboration between multiple people with different expertise—experimental and poromechanical modeling expertise in paper SPE 206144, chemical synthesis and microfluidics expertise in paper SPE 207472, and cement chemistry and experimental expertise in paper SPE 208679. Recommended additional reading at OnePetro: www.onepetro.org. SPE 204103 Evaluation of New Innovative Cement Blend for Enhanced CO2 and H2S Resistance by Gunnar Lende, Halliburton, et al. SPE 206144 Advanced Cement Mechanical Integrity for Thermal Wells by Manh-Huyen Vu, Curistec, et al. SPE 207472 Associative Microgels, New Self-Adaptive Systems To Control Fluid Loss in Well Cementing by Arnaud Cadix, Solvay, et al.

Life cycle assessment of self-healing products

Self-healing products sense and repair damage and should help to improve product circularity and safety. Such products are at an early stage in research and development. Existing models for product life extension in life cycle assessment (LCA) were not developed for self-healing products. It is timely and urgent therefore to develop a framework for life cycle assessment for self-healing products so that their environmental impact can be optimised early at the design stage. This paper presents a new framework for LCA, based on a restoration of a product’s function, and thus linking self-healing to product life extension and user acceptance. The model used within this framework uses the probabilities of self-healing, failure and user acceptance at the end of each life to quantify a product’s service life extension and consequential avoided or delayed new production. The model takes into consideration multiple healing cycles with varying healing efficiencies. A case study scenario of self-healing propeller blades of an unmanned air vehicle employed for site inspection was used to test the application of the framework. The paper shows the positive contribution of self-healing in reducing life cycle impact. Sensitivity analysis revealed a tipping point where the benefits of avoided emissions outweigh the embedded impacts of self-healing technology. This clearly shows the importance of the life cycle assessment framework to understand under which conditions the environmental gains of using self-healing products are maximised.

Synthesis and characterization of layered double hydroxides hybrid microcapsules for anticorrosion via self-healing and chloride ion adsorption

Self-healing and corrosion resistance microcapsule (S/CMC) was fabricated by solvent evaporation method with tung oil (TO) as core, layered double hydroxides (LDH) as corrosion inhibitor and ethyl cellulose (EC) as wall. The average particle size of microcapsule increased with the increase of LDH content when LDH was less than 20 wt%. LDH component was present in the wall of S/CMC by surface loading, the chlorine adsorption performance of microcapsule in neutral environment was superior to that in alkaline environment. LDH was hybridized in EC to form stable wall structure. The LDH embedded in hybrid wall captured chloride ion by surface adsorption and ion exchange to improve the corrosion resistance of steel bar. This study provides a solution for the compatibility of anti-corrosion and self-healing technology, and provides a new perspective for the anti-corrosion application of microcapsule.

Assessing the suitability of self-healing rubber glove for safe handling of pesticides

Rubber gloves used for protection against chemicals or hazards are generally prone to tearing or leaking after repeated use, exposing the worker to potentially hazardous agents. Self-healing technology promises increased product durability and shelf life appears to be a feasible solution to address these issues. Herein, we aimed to fabricate a novel epoxidized natural rubber-based self-healable glove (SH glove) and investigate its suitability for handling pesticides safely. In this study, breakthrough time analysis and surface morphological observation were performed to determine the SH glove’s ability to withstand dangerous chemicals. The chemical resistance performance of the fabricated SH glove was compared against four different types of commercial gloves at different temperatures. Using malathion as a model pesticide, the results showed that the SH glove presented chemical resistance ability comparable to those gloves made with nitrile and NR latex at room temperature and 37 °C. The self-healing test revealed that the SH glove could be self-healed and retained its chemical resistance ability close to its pre-cut value. Our findings suggested that the developed SH glove with proven chemical resistance capability could be a new suitable safety glove for effectively handling pesticides and reducing glove waste generation.

Preparation and performance analysis of dopamine hydrochloride functionalized E-51@MPF/SiO2 double-wall microcapsules for microcracks self-healing in cement-based materials

With the widespread application of cement-based materials, the self-healing problem of microcracks has become increasingly prominent. Self-healing microcapsule technology has received widespread attention due to its excellent healing properties. However, traditional single-walled microcapsules have a series of defects in the actual application process. To better solve this problem, this study used the method of secondary wall construction to prepare dopamine hydrochloride functionalized E-51@MPF/SiO2 double-walled self-healing microcapsules. By combining in situ polymerization and the sol–gel method, based on single-walled MPF, polydopamine-loaded nano-SiO2 particles are introduced to form a double-layer coating structure. Subsequently, a series of microcharacterization experiments were carried out to analyze in detail the morphology, functional groups, particle size, and thermal stability of the functionalized double-walled microcapsules. A uniaxial compression experiment was performed to verify the healing properties of the microcapsules. The results show that dopamine hydrochloride-functionalized double-walled self-healing microcapsules have good compactness, temperature resistance, and healing properties and have excellent particle size. To further analyze the microscopic synthesis mechanism, molecular dynamics simulation was used to elaborate on the two angles of mean square displacement and density distribution. This research innovated self-healing microcapsule technology and improved the safety of cement-based materials in the application process.

Self-healable Hydroxyl-terminated Polybutadiene based Polyurethane for Sustainable Development

Self-healing technology provides a promising road for the sustainable development of the environment, which can extend the service life of materials, thereby reducing the waste of natural resources. As is known to all, it is difficult to obtain a polymer with fast room-temperature self-healing properties without any external stimuli. In this work, a series of polyurethanes with fast room-temperature self-healing capability were designed and prepared by combining the hydrogen bonds and the aromatic disulfide bonds. Owing to their synergistic effect, the obtained polyurethane exhibited high self-healing efficiency of 95.2% for SPU-1, and 98.4% for SPU-2. It is excepted that this design strategy may be potential applications in sustainable development for applied materials.

Concept of self-healing in polymeric materials

Polymer composites are prone to failure as a result of cracks formed during their lifetime. The growth of these cracks may possibly result to tragic failure. Microcracks in structural materials are to be uncovered to ensure that the polymer structures are reliable in terms of performance, cost-effectiveness and safety. Detection of cracks in structural materials are often difficult and the processes of repair are too complicated. Based on the foregoing, the concept of self-healing technology has been developed to find a possible solution to these issues. The self-healing materials have the capability to heal themselves after ruptures have been experienced. From the biological point of view, self-healing polymeric materials with autonomic healing response triggered by rupture have been introduced. This paper aims to discuss the classes of materials, self-healing polymeric materials and self-healing properties and characteristics of the microcapsules.

Interactive mechanism of manufacturing factors on the properties of microbial cementing slurry

In recent years, there has been an increasing interest in microbial self-healing technology in the field of well cementation due to its environmentally friendly, high efficiency, low maintenance cost, and intelligent characteristics. Previous studies have proved that the mechanical strength, setting time, and permeability are the fundamental properties of self-healing cementing slurry which determine the quality of well cementation and the recovery of oil and gas. However, limited research was reported on the effect of manufacturing factors on those basic properties of microbial self-healing cementing slurry in the field of well cementation. In the process of preparation, the air is introduced into the microbial self-healing cementing slurry, causing macropores in the cement stone. Besides, the ammonia produced by microorganisms also results in pores with various size in the microbial cement stone. Those pores which are not conducive to the development of mechanical strength of cement stone might develop into cracks, leading to the failure of well cementation, even causing severely fluids channeling in the wellbore. Therefore, it is of great significance for us to explore the cause of pores in microbial cement stone and choose the proper manufacturing parameters for the field application. In this paper. we studied the influence of manufacturing factors including stirring rate, defoamer dosage and curing ages on the mechanical strength and durability of microbial cement stone. Besides, we explored the interaction mechanism between micro pore structure parameters and macro properties such as compressive strength and permeability of microbial cement stone by the computed tomography technology. The results showed that the number of pores in the microbial cementing slurry was increased with the stirring rate, whereas it was reduced with the increase of defoamer dosage and the extension of curing ages. We also found that there was a poor correlation between the pore structure parameters such as porosity, radius of pores and throats, pore throat ratio and mechanical strength, but a positive correlation between the pore throat ratio and permeability. Moreover, the optimal manufacturing parameters were suggested for the possible field application in this paper. These findings provide a theoretical guidance for the fabrication and application of microbial self-healing cementing slurry in the underground construction buildings besides the well cementation.

Flexible and recyclable bio-based transient resistive memory enabled by self-healing polyimine membrane

The recyclable, self-healing and easily-degradable transient electronic technology has aroused tremendous attention in flexible electronic products. However, integrating the above advantages into one single flexible electronic device is still a huge challenge. Herein, we demonstrate a flexible and recyclable bio-based memory device using fish colloid as the resistive switching layer on a polyimine substrate, which affords reliable mechanical and electrical properties under repetitive conformal deformation operation. This flexible bio-based memory device presents potential analog behaviors including memory characteristics and excitatory current response, which undergoes incremental potentiation in conductance under successive electrical pulses. Moreover, this device is expected to greatly alleviate the environmental problems caused by electronic waste. It can be decomposed rapidly in water and well recycled, which is a promising candidate for transient memories and information security. We believe that this study can provide new possibilities to the field of high-performance transient electronics and flexible resistive memory devices.

Bio-Engineered Concrete: A Critical Review on The Next Generation of Durable Concrete

Concrete is a prerequisite material for infrastructural development, which is required to be sufficiently strong and durable. It consists of fine, coarse, and aggregate particles bonded with a fluid cement that hardens over time. However, micro cracks development in concrete is a significant threat to its durability. To overcome this issue, several treatments and maintenance methods are adopted after construction, to ensure the durability of the structure. These include the use of bio-engineered concrete, which involved the biochemical reaction of non-reacted limestone and a calcium-based nutrient with the help of bacteria. These bio-cultures (bacteria) act as spores, which have the ability to survive up to 200 years, as they are also found to start the mineralization process and the filling of cracks or pores when in contact with moisture. Previous research proved that bio-engineered concrete is a self-healing technology, which developed the mechanical strength properties of the composite materials. The mechanism and healing process of the concrete is also natural and eco-friendly. Therefore, this study aims to critically analyze bio-engineered concrete and its future potentials in the Structural Engineering field, through the use of literature review. The data analysis was conducted in order to provide gradual and informative ideas on the historical background, present situation, and main mechanism process of the materials. According to the literature review, bio-engineered concrete has a promising outcome in the case of strength increment and crack healing. However, the only disadvantage was its less application in the practical fields. The results concluded that bio-engineered concrete is a new method for ensuring sustainable infrastructural development. And also, it indicated that more practical outcome-based analysis with extensive application in various aspects should be conducted, in order to assess the overall durability.

Simulated and Experimental Investigation of the Mechanical Properties and Solubility of 3D-Printed Capsules for Self-Healing Cement Composites.

In the concrete industry, various R&D efforts have been devoted to self-healing technology, which can maintain the long-term performance of concrete structures, which is important in terms of sustainable development. Cracks in cement composites occur and propagate because of various internal and external factors, reducing the composite’s stability. Interest in “self-healing” materials that can repair cracks has led researchers to embed self-healing capsules in cement composites. Overcoming the limitations of polymer capsules produced by chemical manufacturing methods, three-dimensional (3D) printing can produce capsules quickly and accurately and offers advantages such as high material strength, low cost, and the ability to fabricate capsules with complex geometries. We performed structural analysis simulations, experimentally evaluated the mechanical properties and solubility of poly(lactic acid) (PLA) capsules, and examined the effect of the capsule wall thickness and printing direction on cement composites embedded with these capsules. Thicker capsules withstood larger bursting loads, and the capsule rupture characteristics varied with the printing angle. Thus, the capsule design parameters must be optimized for different environments. Although the embedded capsules slightly reduced the compressive strength of the cement composites, the benefit of the encapsulated self-healing agent is expected to overcome this disadvantage.

Thermal and Mechanical Properties of Calcium Alginate Capsules for Self-Healing Asphalt Concrete

The key physical and mechanical property is the strength of the capsules, which ensure the implementation of the self-healing technology, in which the capsules are not destroyed during the compaction of the asphalt concrete mixture, but are destroyed during the formation of defects in the asphalt concrete. An increase in the content of the reducing agent in the composition of the alginate emulsion leads to a decrease in the breaking load during compression of the capsules, which is explained by an increase in their diameter. But the change in the content of sodium alginate does not have a significant effect on mechanical properties. As a result of exposure to a temperature of 170 °C, a decrease in the strength of the capsules by 22 % after 1 hour of exposure in the burning oven is observed, and with an increase in the time to 4 hours, the strength decreases by 46.9 %. The maximum decrease in the strength index after 4 hours of exposure at a temperature of 160 °C reaches 29.9 %. A decrease in temperature to 150 °C leads to a decrease in the loss of strength. The strength of the capsules decreases by 4 % after 4 hours of exposure at 150 °C. Exposure of capsules to a temperature of 140 °C has no significant effect on strength.

Efficient preparation and characterization of calcium alginate-attapulgite composite capsules for asphalt self-healing

Calcium alginate capsules encapsulating rejuvenator are a promising self-healing technology for asphalt pavement, but the high cost and low preparation efficiency of the capsules cannot meet the requirements of application. This research proposed an efficient method for preparing low-cost calcium alginate capsules using industrial calcium sodium and self-developed reaction kettle. To enhance the strength and assure the survival of the capsules in asphalt mixture, attapulgite was incorporated in different proportions to form composite shell capsules, and their microstructure, thermal stability, mechanical strength, and release behavior of the rejuvenator were investigated. It was found that the composite shell capsules prepared with 2.0 wt% industrial sodium alginate solution and industrial sodium alginate to attapulgite ratio 1:1 had clear multi-cavity structure, high thermal stability, and sufficient mechanical strength for their use in asphalt mixture. The multi-cavity composite shell capsules within asphalt mixture can gradually release the rejuvenator inside in wheel tracking test. The test result showed that the capsules can release 82.67% of the rejuvenator and significantly soften the binder when they suffered 115,200 cycles of compression loading (equivalent to 7 years traffic loading on capsules within a medium traffic grade pavement), indicating that the rapid prepared composite capsules can release rejuvenator to soften asphalt binder and enhance the crack-healing property of asphalt pavement during the service life.

Experimental Investigation of a Novel Formulation of a Cyanoacrylate-Based Adhesive for Self-Healing Concrete Technologies

The selection of an appropriate healing agent is critical to the success of vascular and mini-vascular networks. In self-healing concrete technology, commercially available cyanoacrylate (CA) adhesives have been shown to produce good strength recoveries; however, their rapid curing rate and short shelf-life make them unsuitable for site application. The aim of this study was to develop a modified cyanoacrylate (n-CA) with an extended shelf-life suitable for incorporation in a self-healing system. A series of n-CAs were formed from a commercial Ethyl Cyanoacrylate adhesive mixed with acrylic acid (AA) and nitro-anthraquinone (nAq) in varying ratios. When encapsulated within 3D printed mini-vascular networks (MVNs), the n-CAs remained dormant in liquid form for up to 5 days. The contact angle between the n-CAs and the cement mortar substrate, as measured via the sessile drop technique, decreased significantly with increasing AA content. The mechanical properties (bond strength) and the polymerization hardening of the n-CAs were evaluated over a curing period of 7–21 days, via a series of pull-off tests using cement mortar cubes. The 4:1:02 (CA:AA:nAq) n-CA formulation showed a significant increase in bond strength from 14 to 21 days, with a ceiling value of 2.6 MPa, while the 2:1 (CA:AA) n-CA formulation exhibited a good bond strength after 21 days (1 MPa). Nuclear Magnetic Resonance (NMR) conducted on the n-CAs suggested the formation of several new polymeric species, whilst differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) on the pre- and post-printed MVN material confirmed no significant changes in chemistry with no evidence of polymer degradation. Considered together, the experimental results show the potential for different n-CA formulations to act efficiently as a healing agent.

Quality Control and Communication in Smart Grid Using IED & PLCC

In the era of growing power demand and power networks, continuous supply of power and data exchanges is inevitable nurturing the implementation of smart grid technology. The smart grid is a self-healing technology which promises the electricity consumers to be an active participant. However, Intelligent Electronic Device (IED) supports the SG as the backbone for operation imparting the functionalities such as protection and monitoring the power networks. But the limitations of the common IED are its finite allocation of functions without modifying its hardware. Moreover, these IEDs confront the communication problems during natural calamities and other network failures as it adopts the cellular communication topology. The limitations mentioned above can be overcome by adopting the flexible IEDs integrated with signal conditioning, filtering and discretization functions along with the implementation of Power Line Carrier communication. The flexible IED and the PLCC extends the scalability of the most reliable and highly efficient smart grid architecture.