Conductive Hydrogels Research Articles

Multifunctional PVA/PNIPAM conductive hydrogel sensors enabled human-machine interaction intelligent rehabilitation training

Multifunctional PVA/PNIPAM conductive hydrogel sensors enabled human-machine interaction intelligent rehabilitation training

Characterization of Schiff base self-healing hydrogels by dynamic speckle pattern analysis.

Self-healing hydrogels are emerging materials capable of restoring functionality after damage, making them highly suitable for biomedical applications, such as tissue engineering, wound healing, and drug delivery. In this study, we synthesize and characterize a novel biodegradable, conductive, and self-healing hydrogel. The synthesis is based on a Schiff base formed between gelatin and hyaluronic acid, and the dynamic reversible Schiff base bond provides the self-healing property. To characterize and assess the self-healing behavior of the hydrogel, dynamic speckle pattern (DSP) analysis is introduced as a non-destructive, non-contact, and easy-to-implement method. Speckle patterns are formed upon scattering of laser light from a diffusive matter and includes a huge overall information about the sample, to be extracted by statistical processing. DSP analysis is employed to monitor the self-healing process of the hydrogel at both macroscopic and microscopic scales. Experimental procedure involve in situ acquisition of speckle patterns over time under controlled environmental conditions, followed by statistical analysis to evaluate the internal dynamics of the healing process. Several statistical parameters are computed for real-time monitoring of the self-healing property of the hydrogel. The findings, on the one hand, underscore the potential of Schiff base hydrogels in advanced biomedical applications where self-healing properties are critical for sustained performance and longevity. On the other hand, the introduced analysis method shows its potential to serve as an effective approach for biomaterial characterization.

Polydopamine-modified MXene-integrated photothermal responsive hydrogel for constructing rapid photothermal and self-sensing gradi- ent hydrogel actuators

Abstract PNIPAm-based stimuli-responsive hydrogel actuators have made significant progress. By introducing responsive modules such as photothermal nanoparticles, the hydrogel can respond to environmental changes and construct anisotropic structures, allowing the hydrogel actuators to quickly bend and realize complex shape deformation. How-ever, there remains a need to enhance the mechanical properties of these hydrogels to accommodate multiple deformation actions and different application scenarios, and enhance the compatibility between nanoparticles and the hydrogels to improve the comprehensive performance of materials are still issues that need to be solved. In this study, we modified two-dimensional MXene nanosheets with polydopamine (PDA) to obtain P-MXene, which served as a photothermal agent and can be stably dispersed within the hydrogel system. We copolymerized thermosensitive N-isopropylacrylamide (NIPAm) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) in situ and used a direct current (DC) electric field to induce a concentration gradient distribution of P-MXene nanosheets within the hydrogel, resulting in the preparation of anisotropic gradient hydrogel actuators with good stretchability and conductivity. The hydrogel structure was characterized using scanning electron microscopy (SEM) and the Fourier transform infrared (FTIR) spectra. The swelling properties, mechani-cal properties and conductivity of the hydrogel were studied. The actuation behavior of P(NIPAm-DMAEMA)/P-MXene gradient hydrogel actuators under different thickness and electric field intensity was investigated. Additionally, the sensitivity and stability of the conductive hydrogel actuators were tested. and the functions of monitoring human health and information transmission were realized. It integrated with rapid photo responsiveness and self-sensing capabilities to monitor the defor-mation process of the actuators through real-time relative resistance changes during the actuations. This work is expected to expand the application field of soft hydrogel actuators and provide new insights into the design of a new generation of soft robots.

Advances in Electrically Conductive Hydrogels: Performance and Applications.

Electrically conductive hydrogels are highly hydrated 3D networks consisting of a hydrophilic polymer skeleton and electrically conductive materials. Conductive hydrogels have excellent mechanical and electrical properties and have further extensive application prospects in biomedical treatment and other fields. Whereas numerous electrically conductive hydrogels have been fabricated, a set of general principles, that can rationally guide the synthesis of conductive hydrogels using different substances and fabrication methods for various application scenarios, remain a central demand of electrically conductive hydrogels. This paper systematically summarizes the processing, performances, and applications of conductive hydrogels, and discusses the challenges and opportunities in this field. In view of the shortcomings of conductive hydrogels in high electrical conductivity, matchable mechanical properties, as well as integrated devices and machines, it is proposed to synergistically design and process conductive hydrogels with applications in complex surroundings. It is believed that this will present a fresh perspective for the research and development of conductive hydrogels, and further expand the application of conductive hydrogels.

Conductive Hydrogel Materials for Flexible Supercapacitor Electrodes

Flexible supercapacitors (SCs), as promising energy storage devices, have shown great potential for both next-generation wearable electronics and addressing the global energy crisis. Conductive hydrogels (CHs) are suitable electrode materials for flexible SCs on account of their intrinsic characteristics and functional advantages, such as a unique 3D porous structure, remarkable conductivity, tunable chemical and physical properties, and outstanding mechanical properties. Herein, an overview of the fabrication strategies for CHs as electrode materials in flexible SCs, as well as their advantages and disadvantages, and perspectives on CH-based SCs is provided. First, the fabrication strategies for CHs are systematically introduced. Second, various multifunctional CH-based SCs are presented and discussed. Finally, this review concludes with insights into the challenges and opportunities related to CHs or CH-based SCs, indicating future research prospects and application orientations in this field.

Nanocellulose‐reinforced, anti‐freezing, highly conductive ionic organic hydrogels for flexible electronic devices

AbstractCurrently, flexible electronic devices based on ionic conductive hydrogels are receiving widespread attention in the field of human health detection. In this paper, a facile one‐pot method is proposed for the preparation of ionic organic hydrogels, in which polyvinyl alcohol (PVA), cellulose nanofiber (CNF), and graphene oxide (GO) are dissolved in dimethyl sulfoxide‐water (DMSO/H2O), and the organic hydrogel is obtained by a freezing–thawing process. The ionic organic hydrogel with excellent properties is then prepared by soaking the hydrogel in a calcium chloride (CaCl2) solution using a salting‐out strategy. The ionic organic hydrogel possesses good tensile (283%) and strength (0.3 MPa), super electrical conductivity (7.72 S/m), and high strain sensitivity [gauge factor (GF) up to 5.22]. Meanwhile, it has excellent anti‐freezing and moisturizing properties. In addition, the ionic organic hydrogels can be used in flexible strain sensors and triboelectric nanogenerators to realize real‐time monitoring of human motion, traceless writing, and energy conversion. It is foreseen that the prepared ionic organic hydrogels provide a feasible method for realizing the long‐term use of wearable electronic devices in extreme environments and daily life.

Mechanoresponsive self‐powered piezoelectric energy‐generating composite hydrogels based on carbon nanotube‐reinforced fungal‐carboxymethyl chitosan‐bacterial cellulose nanofibers for wearable electronics

AbstractDeveloping conductive hydrogels with both enhanced mechanical properties and superior sensing capabilities for wearable, flexible electronics remains challenging. Here, we developed mechanoresponsive self‐powered piezoelectric energy‐generating composite hydrogels. These hydrogels were prepared by blending fungal‐derived carboxymethyl chitosan (FC), carboxylate‐bacterial cellulose nanofibers (CBC‐NFs), and carbon nanotubes (CNTs) within a covalently crosslinked polyacrylamide (PAM) network (CNT‐FBCNF). The resulting hydrogels showed remarkable mechanical properties due to the molecular interactions between polymer chains. The hydrogels showed a self‐recoverable property and high stability under compressive mechanical force at 40% of strain (2000 cycles). The maximum compressive load (N) of 27.8 N was obtained for the optimized hydrogel, CNT‐FBCNF (1% CNT content). This hydrogel exhibited a good conductivity of 1.3 S/m, which was attributed to the homogeneous dispersion of CNTs within the hydrogel matrix and sufficient biocompatibility with skin fibroblasts. The hydrogel also exhibited impressive performance as a strain sensor, boasting a wide strain range (10–40%), excellent stability, and repeatability. Furthermore, strategic cutting and assembly of the hydrogel generated a flexible strain sensor capable of accurately monitoring finger and thumb pressure in real‐time. This study will significantly accelerate the development of hydrogel‐based sensors within the rapidly advancing field of wearable soft electronics.Highlights CNT‐reinforced composite hydrogel was developed The optimized hydrogel showed good electrical conductivity (1.3 S/m) The optimized hydrogel showed good self‐recovery properties The optimized hydrogel exhibited impressive strain‐sensing capability between 10% and 40% strain

Conductive polyphenol microneedles coupled with electroacupuncture to accelerate wound healing and alleviate depressive-like behaviors in diabetes

Inflammation and depression are serious complications of diabetes that interact to form a feedback loop and may hinder diabetic wound healing. They share a common pathophysiological basis of abnormal interactions between diabetic wounds and the brain. Here, we propose a strategy combining electroacupuncture (EA) stimulation of the Dazhui acupoint (GV14) with polyphenol-mediated conductive hydrogel microneedles to promote diabetic wound healing and alleviate depression through local wound–brain interactions. The conductive microneedles comprised methacrylated gelatin, dopamine (DA), DA-modified poly(3,4-ethylenedioxythiophene), and Lycium barbarum polysaccharide. EA at GV14 activated the vagus–adrenal axis to inhibit systemic inflammation while DA coupled electrical signals for long-term inhibition of local wound inflammation. EA at GV14 was also found to elevate 5-hydroxytryptamine levels in rats with diabetic wounds, consequently mitigating depressive-like behaviors. Additionally, the polyphenol-mediated conductive hydrogel microneedles, and coupled with EA stimulation promoted healing of wound tissue and peripheral nerves. This strategy regulated both local and systemic inflammation while alleviating depressive-like behaviors in diabetic rats, providing a new clinical perspective for the treatment of diabetes-related and emotional disorders.

Ultrasensitive conductive hydrogels conferred by nanoscale synergistic effect

Ultrasensitive conductive hydrogels conferred by nanoscale synergistic effect

Silver Nanoparticle-Decorated Cellulose Nanocrystal Reinforced Ionic Polymer Hydrogel With High Conductivity and Environmental Tolerance for Multifunctional Sensing and Emergency Alarm System.

Conductive hydrogels hold great promise for flexible electronics. However, the simultaneous achievement of satisfactory mechanical strength, outstanding environmental tolerance, high sensitivity, and multiple sensing applications in a single conductive hydrogel remains a significant challenge. Herein, ionic polymer-based hydrogels with a double conductive network consisting of [2-(methacryloyloxy)ethyl] trimethyl ammonium chloride (DMC), 2-hydroxyethyl acrylate (HEA) and silver nanoparticle decorated cellulose nanocrystal (CNC@Ag) are prepared by a facile one-pot method. The resultant hydrogel (CDH) exhibits high stretchability, satisfactory self-adhesion, excellent environment tolerance (from -60 to 60°C), long-term stability (60 days), effective UV-shielding, and strong antibacterial properties. Significantly, the CDH hydrogel displays high conductivity and rapid response due to its double conductive network of ionic polymer and CNC@Ag. Therefore, the CDH-assembled sensor can accurately detect signals from both strain and pressure deformations, exhibiting outstanding sensitivity and reliability for human motion detection, signal transmission, object recognition, and tactile sensing. More interestingly, collaborating with a development board, the CDH-based sensor can be developed as an emergency alarm to realize prompt alarms in dangerous situations. Overall, this work presents a strategy for the fabrication of conductive hydrogel with remarkable properties, making it possible for multifunctional sensing applications in wearable electronics.

Alphabet Handwriting Recognition: From Wood-Framed Hydrogel Arrays Design to Machine Learning Decoding.

Handwriting recognition is a highly integrated system, demanding hardware to collect handwriting signals and software to deal with input data. Nonetheless, the design of such a system from scratch with sustainable materials and an easily accessible computing network presents significant challenges. In pursuit of this goal, a flexible, and electrically conductive wood-derived hydrogel array is developed as a handwriting input panel, enabling recognizing alphabet handwriting assisted by machine learning technique. For this, lignin extraction-refill, polypyrrole coating, and polyacrylic acid filling, endowing flexibility, and electrical conduction to wood are sequentially implemented. Subsequently, these woods are manufactured into a 5×5 array, creating a matrix of signals upon handwriting. Efficient handwritten recognition is then achieved through appropriate manual feature extraction and algorithms with low complexity within a computing network, as demonstrated in this work, the strategic choice of expertise-based feature engineering and simplified algorithms effectively boost the overall model performance on handwriting recognition. With potential adaptability, further applications in customized wearable devices and hands-on healthcare appliances are envisioned.

Electrospun green fluorescent-highly anisotropic conductive Janus-type nanoribbon hydrogel array film for multiple stimulus response sensors

A new strategy aimed at significantly enhancing the anisotropic conductivity of hydrogel materials, along with a simple construction technology and design concept, are proposed. Anisotropic conductive hydrogel materials have attracted much attention from researchers in the field of flexible electronics for their inherent excellent properties. However, the anisotropic conductivity of the existing conductive hydrogels is not high and the preparation methods are complex. Herein, fluorescent-highly conductive anisotropic Janus-type nanoribbon hydrogel array film (named JNHAF) is successfully prepared using a combination of parallel electrospinning and post-polymerization as an example of the study. Highly oriented [2,7-dibromo-9-fluorenone (DF)/gelatin (GE)]//[carbon black (CB)/GE] Janus-type nanoribbon is used as the building block. The composition as well as the arrangement of Janus-type nanoribbons are microscopically designed and regulated to effectively separate the conductive and insulating materials, so that the samples can achieve highly anisotropic conductivity and obvious green fluorescence. When the mass ratio of GE to CB is 1:0.1, the conductive anisotropy ratio of JNHAF can reach 1.12 × 105. The degree of anisotropic conductivity of JNHAF is significantly improved compared with existing reported anisotropic conductive hydrogels, and the preparation method is simple. JNHAF responds quickly to light, tensile strain, and temperature, making it suitable for assembling multi-stimulus responsive sensors. JNHAF has excellent flexibility, degradability, mechanical properties and a certain degree of sensitivity (gauge factor of 4.29), and is used for human joint motion detection with an obvious response signal. The design idea and construction technology of this hydrogel breaks through the technical bottleneck of the low degree of anisotropy of conductive hydrogels, which will lead and expand the scientific frontiers of anisotropic conductive hydrogel materials, and provide novel design ideas and theoretical values for new hydrogel materials.

Human Muscle Inspired Anisotropic and Dynamic Metal Ion-Coordinated Mechanically Robust, Stretchable and Swelling-Resistant Hydrogels for Underwater Motion Sensing and Flexible Supercapacitor Application.

Mechanically robust and anisotropic conductive hydrogels have emerged as crucial components in the field of flexible electronic devices, since they possess high mechanical properties and intelligent sensing capabilities. However, the hydrogels often swell on exposure to aqueous medium because of their hydrophilicity, which compromises their mechanical properties. Additionally, the hydrogels' isotropic polymeric networks demonstrate isotropic ion transport, which significantly diminishes the sensing capabilities of electrical devices based on hydrogels. These factors greatly limit their use in flexible and wearable sensors. In this study, we have developed poly(acrylamide-co-maleic acid-co-butyl acrylate) based anisotropic hydrogels by prestretching and drying, followed by ionic cross-linking to fix the alignment. The anisotropic arrangement of the polymer network resulted in significant improvements in mechanical performance and electrical conductivity along the prestretching direction. This anisotropic hydrogel combines hydrophobic and metal ion-ligand interactions, enhancing the maximum tensile strength up to 11 MPa along the prestretching direction, about 3 times higher than in the perpendicular direction. The optimized 200% prestretched hydrogel exhibited high tensile strength (7 MPa), flexibility (fracture strain 370%), high toughness (16 MJ m-3) and antiswelling behavior in water (equilibrium swelling ratio 2% after 15 days). alongside higher conductivity (3 times higher) and strain sensing ability (4 times higher gauge factor) along the prestretching direction. The hydrogel demonstrated efficient and stable underwater sensing for underwater communication and to monitor human limb position and movement. The anisotropic hydrogel electrolyte-based flexible supercapacitor exhibited 117 Fg-1 specific capacitance at 0.5 Ag-1, and maximum energy density 5.85 Whkg-1, significantly higher than the corresponding values for the isotropic hydrogel-based device (88 F g-1 and 4.4 Whkg-1, respectively). This hydrogel mimics the structural design of unidirectionally oriented muscle fibers, showing better direction dependent functional properties than the corresponding isotropic hydrogel. The anti-swelling ability and retention of mechanical and conductive properties of these hydrogels in aqueous environment suggest long-term usage capability of these functional materials.

Stretchable, self-adhesive, and conductive hemicellulose-based hydrogels as wearable strain sensors

Conductive hydrogels have recently gained impressive attention in flexible sensing. However, their low sensing limit and poor interface matching have raised great concern during the practical application. Therefore, incorporating excellent stretchability and adhesiveness into conductive hydrogel is highly desirable but still be a huge challenge. In this study, we synthesized composite hydrogels with desired properties by utilizing the synergistic role of hemicellulose (HC) and conductive two-dimensional material MXene. As a result, the synthesized hydrogels showed good self-adhesion (3.12 KPa on the skin), great stretchability (>1700 %), and satisfactory electrical conductivity. These multifunctional hydrogels operated as adaptable sensors, adeptly capturing the nuanced signals emanating from an array of human motions. They exhibited an expansive strain tolerance, swift reactivity, and an enhanced acuity in detecting even the slightest deformations (GF = 2.1). Our research provides new insights for creating stretchable, self-adhesive, and functional hydrogels for sensing applications.

Conductive hydrogels: Intelligent dressings for monitoring and healing chronic wounds

Abstract Conductive hydrogels (CHs) represent a burgeoning class of intelligent wound dressings, providing innovative strategies for chronic wound repair and monitoring. Notably, CHs excel in promoting cell migration and proliferation, exhibit powerful antibacterial and anti-inflammatory properties, and enhance collagen deposition and angiogenesis. These capabilities, combined with real-time monitoring functions, play a pivotal role in accelerating collagen synthesis, angiogenesis, and continuous wound surveillance. This review delves into the preparation, mechanisms, and applications of CHs in wound management, highlighting their diverse and significant advantages. It emphasizes the effectiveness of CHs in treating various chronic wounds, such as diabetic ulcers, infected wounds, temperature-related injuries, and athletic joint wounds. Additionally, it explores the diverse applications of multifunctional intelligent CHs in advanced wound care technologies, encompassing self-powered dressings, electrically-triggered drug delivery, comprehensive diagnostics and therapeutics, and scar-free healing. Furthermore, the review highlights the challenges to their broader implementation, explores the future of intelligent wound dressings, and discusses the transformative role of CHs in chronic wound management, particularly in the context of the anticipated integration of artificial intelligence (AI). Additionally, this review underscores the challenges hindering the widespread adoption of CHs, delves into the prospects of intelligent wound dressings, and elucidates the transformative impact of CHs in managing chronic wounds, especially with the forthcoming integration of artificial intelligence (AI). This integration promises to facilitate predictive analytics and tailor personalized treatment plans, thereby further refining the healing process and elevating patient satisfaction. Addressing these challenges and harnessing emerging technologies, we postulate, will establish CHs as a cornerstone in revolutionizing chronic wound care, significantly improving patient outcomes.

High-strength polyvinyl alcohol/gelatin/LiCl dual-network conductive hydrogel for multifunctional sensors and supercapacitors

The synthesis of conductive hydrogels with high mechanical strength, toughness, optimal fracture growth rate and the capability to detect diverse human body movements poses a significant challenge in the realm of flexible electronics. In this study, a one-pot technique utilized effectively to fabricate conductive materials by doping LiCl into a mixture of polyvinyl alcohol (PVA) and gelatin. The PVA/gelatin/LiCl0.3(PGL) conductive hydrogel demonstrates exceptional robustness, flexibility, and resistance to deformation, enabling the monitoring of various physiological signals such as temperature and humidity. Additionally, the PGL demonstrates exceptional elongation properties (up to 1111.32 %), high lifting capacity (up to 25 kg), resistance to deformation, and sustained stability of peak signals even after 300 cycles at 50 % strain. The hydrogel electrolyte exhibits a conductivity of 2.114 S/m at 25 °C and a specific capacitance of up to 48.75 F/g, along with favorable mechanical and electrochemical characteristics. These findings suggest that the PVA/gelatin/LiCl0.3 hydrogel supercapacitor (PGLSC) conductive hydrogel shows significant potential for integration into flexible electronics and wearable technology devices.

Construction of high strength PVA/cellulose conductive hydrogels based on sodium citrate/aluminium chloride dual ions regulation

Hydrogels used for flexible sensing usually require a good balance between mechanical strength and conductivity. In this study, polyvinyl alcohol/carboxymethyl cellulose/cellulose nanofibers (PVA/CMC/CNF) hydrogels with multi-hierarchical structures were firstly prepared by adjusting the CNF content. Then, PVA/CMC/CNF-xM with excellent mechanical properties and conductivity were prepared by cyclic freezing-thawing and sodium citrate/aluminium chloride (Na3Cit/AlCl3) dual ions salt equilibrium methods. Results showed that at an ion concentration of 3 mol/L, PVA/CMC/CNF-3 M hydrogel exhibited a tensile strength, elongation at break and conductivity of 3.41 MPa, 1271 % and 0.35 S/m, respectively. The structural evolution of PVA/CMC/CNF-xM conductive hydrogels were studied, and the results indicated that Cit3− formed numerous intermolecular hydrogen bonds, while Al3+ could strongly coordinate with carboxyl and hydroxyl groups between the polysaccharide chains. Meanwhile, PVA/CMC/CNF-3 M possessed a low strain detection limit of 1 %, making it not only can be used for human motion monitoring, but also information encoding and transmission. This work may provide a facile approach for preparing high-strength and conductive hydrogels, which can be applied in flexible wearable electronic devices and information transmission.

Preparation and characterization of neural stem cell-loaded conductive hydrogel cochlear implant electrode coatings

Sensorineural deafness is a hearing impairment resulting from damage to the auditory nerve or inner ear hair cells. Currently, cochlear implants (CIs) are widely used as hearing aids for sensorineural deafness patients. A fundamental limitation of cochlear implants (CIs) is that spiral ganglion neurons (SGNs) cannot be replenished. This greatly restricts the rehabilitation of sensorineural deafness. Additionally, the insertion of CIs can cause secondary cochlear damage, worsening the condition of the patients' cochlear. Therefore, a new type of neural stem cells (NSCs) loaded graphene oxide-polyaniline/GelMA (GO-PAni/GelMA) conductive hydrogel electrode for cochlear implant was fabricated via in-situ radical polymerization and cyclic UV curing technique. On the one hand, the hydrogel electrode, as a direct contact layer, helps to avoid the physical hurt for cochlear. On the other hand, NSCs were supplemented via the hydrogel carrier and neuronal differentiation was induced by electrical stimulation, which was validated by the experimental results of immunofluorescence, Phalloidin Staining and RT-qPCR. Furthermore, based on RNA sequencing and transcriptome analysis, we hypothesized that the neuronal differentiation of NSCs was adjusted by the calcium signaling pathway and GABAergic synapse. Overall, our cell loading conductive hydrogel electrode may be an effective solution to sensorineural deafness. The revelation of the mechanism of neuronal differentiation promoted by electrical stimulation provides a basis for further sensorineural deafness treatment using conductive hydrogel CI electrode.

Self-adhesive, mechanically strong, and conductive organogel for flexible/wearable electronics and underwater electronic skin

Due to their flexibility, self-healing ability, and biocompatibility, conductive hydrogels have become excellent candidates for flexible electronics. However, challenges remain, such as water evaporation when exposed to air, resulting in a loss of flexibility and conductivity. Additionally, traditional hydrogels quickly swell underwater, which causes irreversible damage to their structure and electrical properties. As a promising alternative, organogels have gained attention for overcoming these drawbacks. Here, we report a transparent, multifunctional organogel using ultraviolet-initiated polymerization, which exhibits excellent adhesion, robustness, electrical and interfacial stability, and super stretchability. By adjusting the concentration of the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), the conductivity of organogel could be easily regulated from non-conductive to conductive, obtaining non-conducting elastomer (NCE, without LiTFSI) and ion-conducting elastomer (ICE, with LiTFSI) with identical mechanical properties and superior adhesion due to the same composing polymer chains. This unique characteristic overcomes the interface mismatch problem of traditional flexible electronic devices. Moreover, a high-performance triboelectric nanogenerator (TENG) was designed (ICE-TENG) to achieve a maximum power density of 151.3 μW cm−2, which was utilized to power small electronics. Additionally, a strain sensor was constructed using the ICE, realizing underwater sensing and communication with high stability. This multifunctional organogel is promising for multi-functional human–machine interaction.

Environmentally stable and multi-functional conductive gelatin/PVA/black wattle bark tannin based organogel as strain, temperature and bioelectric sensor for multi-mode sensing

Conductive hydrogels are regarded as ideal candidates for the application of flexible sensors owing to their excellent flexibility, portability and conductivity. However, it is still challenging and meaningful to prepare multifunctional (self-healing, adhesion, anti-freezing, biocompatibility, antibacterial and conductivity properties) and multi-mode sensing hydrogel-based sensors. Herein, we developed an environmentally stable and multi-functional conductive organogel via dynamic crosslinks based on biomass materials gelatin, black wattle bark tannin and PVA in the propylene glycol/water binary solvent system. Thanks to the dynamic interactions in the system, the good mechanical strength and self-healing performance of the obtained organogel are simultaneously realized. Meanwhile, the organogel integrates many crucial properties such as adhesion, environmental stability (anti-freezing and water retention), biocompatibility, antibacterial behavior and conductivity capacity. Significantly, the organogel can be assembled as three-mode sensors for strain, bioelectricity and temperature sensing. This three-mode sensor can effectively monitor human health data, resulting in providing supplement human health information and conditions. This work displays an interesting approach to construct an intelligent multi-functional conductive biomass organogel based multi-mode flexible sensors.