A systematic review led by researchers Marielen Longhi, Vanessa Bueno Pereira, and Heitor Luiz Ornaghi Júnior has analyzed the development of self-healing elastomeric composites integrated with carbon dot-based supercapacitors for wearable sensor technology. Published in Discover Polymers, the investigation adhered to the established Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to address defined research questions while curbing procedural bias. The authors executed comprehensive literature searches across three primary academic indexing databases—Science Direct, Springer Nature Link, and IEEE Xplore—covering peer-reviewed studies published in English between 2016 and 2025. Initial search queries targeting elastomeric materials, carbon dots, and supercapacitors yielded thirty candidate publications, which were subsequently subjected to independent dual-reviewer screening by evaluating study titles and abstracts. Review articles, conference proceedings, and papers lacking all three designated abstract keywords were systematically excluded from consideration. Following duplicate elimination and rigorous eligibility appraisal, nineteen primary research investigations were incorporated into the final qualitative synthesis. The systematic assessment concentrated specifically on rheological, thermal, mechanical, biological, and electrical performance parameters, mapping documented experimental breakthroughs while isolating critical technical deficiencies across contemporary device designs.
The underlying rationale for developing self-healing wearable electronics rests on counteracting undetectable matrix damage, including brittle microcracks prompted by environmental stress, which compromises device functionality and prompts premature disposal. The review delineates two major classifications of repair behavior: autonomous extrinsic systems and externally assisted intrinsic mechanisms. Extrinsic strategies traditionally embed sacrificial capsules or intricate vascular conduits containing liquid healing agents that polymerize across ruptured interfaces upon cracking. Nevertheless, microcapsule approaches remain predominantly restricted to a single repair occurrence, are constrained by capsule dimensions spanning 100 to 200 micrometers, and depend strictly on precise stoichiometric ratios between monomers and hardeners. Vascular frameworks permit multiple autonomous healing cycles, but they present complex scaffold fabrication demands and risk channel blockage caused by prematurely solidified agents. In contrast, intrinsic self-healing mechanisms exploit reversible dynamic interactions within polymer networks—such as imine covalent exchange, hydrogen bonding, coordination complexes, and ionic associations—that permit repeated structural and functional restoration upon exposure to external thermal, optical, or mechanical inputs, although historically concentrated primarily within thermoplastic rather than thermoset architectures.
Material upcycling and sustainable raw material utilization represent prominent avenues within current elastomeric sensor development, as documented across several evaluated primary investigations. Utrera-Barrios and colleagues demonstrated an environmental approach by recycling polymer components from spent toner cartridges into functional thermoplastic elastomers. Their formulation blended carboxylated nitrile rubber as the elastomeric matrix with high-impact polystyrene recovered from cartridge casings, incorporating residual black toner powder composed of carbon black and silica as a functional reinforcing additive. The resulting composite achieved a tensile strength of 6.6 ± 0.2 MPa alongside complete mechanical recovery of 100% when subjected to thermal cycles. The inclusion of toner particles up to 20 parts per hundred rubber yielded a 50% increase in tensile strength compared to unfilled matrices by balancing mechanical stiffness against molecular chain mobility. This structural performance was governed by dual healing modes: an extrinsic phase transition of the recycled polystyrene phase and an intrinsic healing process driven by reversible ionic crosslinks formed between carboxyl groups on the nitrile rubber backbone and zinc oxide domains.
Progress in self-healing electrolytes has similarly expanded the capabilities of multi-responsive skin-attachable devices capable of operating without protective encapsulation. Kim and colleagues engineered a multi-responsive, air-stable ionogel incorporating the hydrophilic ionic liquid 1-ethyl-3-methylimidazolium ethyl sulfate within a poly(acrylic acid) network crosslinked with gold nanoparticles functionalized by N, N’-bis(acryloyl)cystamine. This conductive gel was combined with multi-walled carbon nanotube electrodes spray-deposited on graphite paper current collectors to assemble flexible supercapacitors alongside integrated strain sensors. The ionogel exhibited an intrinsic ionic conductivity of 1.91 mS cm⁻¹ at ambient temperature, increasing to 7.48 mS cm⁻¹ at 60 °C, while preserving an electrochemical operating window from −2.0 V to +2.0 V without significant leakage current. The fabricated supercapacitor achieved a maximum areal capacitance of 20.4 mF cm⁻² at 0.1 mA cm⁻², an energy density of 12.1 µWh cm⁻², and a power density of 2.45 mW cm⁻², retaining 87% of capacitance across 10,000 charge-discharge cycles and 95.3% across 5,000 bending cycles. Structural recombination via thermal treatment at 65 °C restored 99.3% of mechanical integrity within three hours, whereas near-infrared optical stimulation at 808 nm achieved 101.8% mechanical recovery in thirty minutes, enabling skin-mounted motion detection powered directly by on-board energy storage.
Hydrogel platforms have likewise advanced through the incorporation of nanohybrid fillers that simultaneously address typical trade-offs between electrical conductivity, mechanical elasticity, and autonomous self-repair speeds. Han and co-workers developed electro-conductive hydrogels by embedding carbon nanotube and cellulose nanofiber hybrids into a polyvinyl alcohol-borax matrix. The cellulose nanofibers served as uniform dispersants that stabilized suspended carbon nanotubes, establishing a conductive and reinforcing dual network. The resulting composite hydrogel exhibited a compression stress of approximately 93 kPa at 90% strain and a storage modulus of roughly 7.12 kPa, reflecting values 2.7 and 1.9 times greater than those of control hydrogels devoid of carbon nanotubes. The hydrogel possessed an ambient density of 1.1 g cm⁻³, a water fraction of approximately 95%, and autonomous mechanical recovery within 20 seconds, regaining over 93% of its original strength without external stimuli. Dynamic complexation between borate ions and hydroxyl groups on the polymer and nanohybrid backbones allowed severed gel segments to re-establish interface continuity rapidly. Supercapacitors built from these materials delivered a specific capacitance of 117.1 F g⁻¹, retaining 96.4% capacitance after 1,000 galvanostatic cycles and 98.2% capacitance after ten sequential cutting and healing operations.
The review highlights room-temperature intrinsic healing systems designed to eliminate requirements for elevated thermal exposure or specialized laser equipment. Min and colleagues synthesized conductive composites featuring reversible imine covalent bonds reinforced with carbon nanotubes and carbon black. These composites recorded an ultimate mechanical strength of 6.6 MPa and an electrical resistivity of 108 Ω·m, achieving room-temperature healing efficiencies of 96% for mechanical recovery and 93% for electrical conductivity through reversible imine bond exchanges. In parallel, Li and collaborators formulated polyacrylamide hydrogels crosslinked in situ with polydopamine-functionalized carbon nanotubes for multifunctional biometric monitoring. Catecholamine groups on the modified nanotubes promoted dynamic π–π stacking, cationic-π interactions, and hydrogen bonding, providing 97.3% mechanical healing efficiency after six hours of interfacial contact at ambient temperature. Wearable strain sensors derived from this nanocomposite demonstrated gauge factors of 1.99 across strains up to 200% and 3.93 across strains between 200% and 400%, maintaining rapid response times of 95 ms and recovery times of 76 ms. Triboelectric nanogenerators based on this material demonstrated linear pressure-voltage relationships, facilitating self-powered tactile sensing and Morse code signal transmission across healthcare interfaces.
Environmental durability across broad temperature fluctuations has emerged as another essential benchmark evaluated within the reviewed literature. Jung and colleagues developed an organohydrogel electrolyte utilizing water and ethylene glycol solvent mixtures incorporating functionalized carbon nanotubes, creating a resilient dual-function supercapacitor and strain sensor. The inclusion of ethylene glycol suppressed water freezing down to −49 °C and limited evaporation up to 80 °C through intensified hydrogen bonding with polyvinyl alcohol chains. The resulting supercapacitor demonstrated gravimetric capacitances of 123.4 F g⁻¹ at −20 °C, 147.0 F g⁻¹ at 25 °C, and 156.2 F g⁻¹ at 80 °C, fully recovering initial capacitance after three cycles between these thermal extremes and maintaining capacitance over 10,000 cycles. Concurrently, the integrated strain sensor retained stable gauge factors of 1.61 at −20 °C, 1.77 at 25 °C, and 1.50 at 80 °C. Similarly, Chen and associates synthesized conductive elastomers by combining amino-functionalized cellulose nanofibers with glycidyl methacrylate and deep eutectic solvents, generating a dual crosslinked network that demonstrated a tensile strength of 3.24 MPa, an elongation at break of 1698.99%, and a high storage modulus of 7.7 × 10⁵ Pa, operating effectively across challenging environmental conditions.
Biocompatibility and cellular non-toxicity remain strict prerequisites for wearable biosensors intended for epidermal placement, as highlighted across multiple biological assays compiled by the authors. Ghaffari-Bohlouli and co-workers synthesized bio-elastomers based on poly(glycerol-sebacate-itaconic acid) crosslinked with polypyrrole and nanoclay, recording a Young’s modulus of 0.68 to 2.5 MPa and tensile strengths up to 1.75 MPa, parameters well matched to soft biological tissues. In vitro MTT assays utilizing mouse L929 fibroblasts established that composites containing 3 wt% clay and 3 wt% polypyrrole exhibited no cytotoxicity, displaying 22% higher cell viability than unmodified polyester matrices after seven days due to enhanced surface hydrophilicity. In related investigations, Li and colleagues demonstrated a 90% increase in L929 cell density over a three-day culture on polydopamine-modified hydrogels. Zhang and colleagues introduced polyvinyl alcohol aerogels incorporating cellulose nanocrystals, graphene nanosheets, and silver nanoparticles, demonstrating 74 MPa tensile strength, 1.8 MPa compressive strength, and clear antibacterial activity against Escherichia coli and Staphylococcus aureus via silver ion concentration gradients. Guan and colleagues verified epidermal safety for hydrophobic paper-based MXene sensors, observing an absence of skin irritation or inflammation across seven days of human epidermal contact.
Piezoresistive sensing precision and electromechanical stability across prolonged deformation regimens were consistently documented among paper and biopolymer composites. Panwar and co-workers synthesized cost-effective ionic polymer nanocomposites by reducing silver nitrate in aqueous polyvinyl alcohol using liquid sugarcane extract, which served simultaneously as a natural reducing agent and ionic conduction medium. Their optimized formulation with a 1/0.3 precursor ratio generated uniformly distributed metallic nanoparticles ranging from 18 to 53 nm in diameter. This architecture produced an ionic conductivity of 1.0 × 10⁻⁴ S/cm, a dielectric constant up to 100 times higher than unmodified ionic polymers, a current density of 14 mA/cm², and a capacitance of 700 mF/cm², achieving a gauge factor of 307 and a sensitivity of 5.7 to monitor pulse waveforms, respiration, coughing, and finger flexion over 6,000 cycles. Complementing this, Guan and colleagues created breathable paper-based strain sensors coated with conductive MXene and hydrophobic biomass sizing agents, achieving a contact angle of 133.4°, air permeability of 154.08 mm/s, a gauge factor of 161 across bending angles from 0° to 120°, and sustained functionality across 100,000 bending cycles at 30°.
Looking toward commercial integration, the authors note economic projections forecasting that the global supercapacitor market will expand to US$ 4.86 billion by 2036, advancing at a compound annual growth rate of 15.3% as demand shifts from automotive start-stop mechanisms toward renewable grid stabilization and industrial electronics. However, the systematic review concludes that widespread deployment of self-healing elastomeric wearables remains constrained by significant technological obstacles. Syntheses frequently involve complex reaction pathways, costly starting reagents, and volatile intermediates such as amines, isocyanates, and free radicals that restrict chemical shelf life. Many existing intrinsic systems continue to demand rigorous external interventions, including elevated temperatures or targeted irradiation, failing to execute autonomous repair under unassisted ambient conditions. Extended operational exposure also prompts progressive property degradation, as ambient dust or atmospheric moisture occupies dynamic bond sites, slowing molecular chain mobility. The authors emphasize that future research must prioritize developing multi-network molecular architectures—balancing sacrificial non-covalent interactions for healing efficiency against robust dynamic covalent bonds for load-bearing strength—while establishing standardized testing metrics and demonstrating scalable, cost-efficient manufacturing routes.
Subject of Research: Systematic review of self-healing elastomeric composites and supercapacitors for wearable sensors
Article Title: A comprehensive review on self-healing polymeric composites based wearable sensor
Article References: Longhi, M., Pereira, V. B., & Ornaghi Júnior, H. L. (2026). A comprehensive review on self-healing polymeric composites based wearable sensor. Discover Polymers, 3(1), Article 7. https://doi.org/10.1007/s44347-026-00045-9
Image Credits: AI Generated
DOI: 10.1007/s44347-026-00045-9
Keywords: wearable sensors, self-healing polymers, supercapacitors, elastomeric composites, carbon dots, flexible electronics, materials science, systematic review, comprehensive, review, self-healing, polymeric
