Stretchable Organohydrogel with Adhesion, Self-Healing, and Environment-Tolerance for Wearable Strain Sensors

Phytic acid/chitosan-assisted zwitterionic double-network hydrogels with enhanced mechanical properties, adhesion ability and ionic conductivity for wearable strain sensors

Ionic conductive hydrogels have recently attracted tremendous attention in flexible wearable strain sensors. However, achieving a combination of good mechanical properties, strong adhesion to various material surfaces, and remarkable ionic conductivity in a single ionic conductive hydrogel remains a challenge. Herein, new poly(acrylamide-co-sulfobetaine methacrylate)/chitosan/phytic acid (ASCP) ionic conductive hydrogels with double networks were prepared through free radical polymerization. The versatile functional groups from chitosan and phytic acid gave the hydrogels universal adhesion capabilities with a maximum adhesion strength of 18.7 kPa to paper. The obtained ASCP conductive hydrogels exhibited a large elongation of 675 % and a moderate tensile strength 52.8 kPa due to the synergy of chemical cross-linking and physical interactions. Phytic acid as the conductive component conferred the hydrogels with excellent ionic conductivity of 10.3 S m-1. Moreover, the incorporation of chitosan and phytic acid imparted the hydrogels with enhanced anti-drying capability, as evidenced by a residual mass ratio of 58.3 % after 10 days, and exhibited favorable anti-swelling behavior, with an equilibrium swelling ratio of 115 % in water after 4 days. The described ionic conductive hydrogels were assembled into wearable strain sensors to detect various human joint movements. This work offers a straightforward strategy to design multifunctional conductive hydrogels which envision prospective applications in wearable sensors and other flexible electronic devices.

High-Conductivity, Self-Healing, and Adhesive Ionic Hydrogels for Health Monitoring and Human-Machine Interactions Under Extreme Cold Conditions

Ionic conductive hydrogels (ICHs) are emerging as key materials for advanced human-machine interactions and health monitoring systems due to their unique combination of flexibility, biocompatibility, and electrical conductivity. However, a major challenge remains in developing ICHs that simultaneously exhibit high ionic conductivity, self-healing, and strong adhesion, particularly under extreme low-temperature conditions. In this study, a novel ICH composed of sulfobetaine methacrylate, methacrylic acid, TEMPO-oxidized cellulose nanofibers, sodium alginate, and lithium chloride is presented. The hydrogel is designed with a hydrogen-bonded and chemically crosslinked network, achieving excellent conductivity (0.49 ± 0.05 S m-1), adhesion (36.73 ± 2.28 kPa), and self-healing capacity even at -80 °C. Furthermore, the ICHs maintain functionality for over 45 days, showcasing outstanding anti-freezing properties. This material demonstrates significant potential for non-invasive, continuous health monitoring, adhering conformally to the skin without signal crosstalk, and enabling real-time, high-fidelity signal transmission in human-machine interactions under cryogenic conditions. These ICHs offer transformative potential for the next generation of multimodal sensors, broadening application possibilities in harsh environments, including extreme weather and outer space.

Natural polysaccharides-based smart sensors for health monitoring, diagnosis and rehabilitation: A review

With the rapid growth of multi-level health needs, precise and real-time health sensing systems have become increasingly pivotal in personal health management and disease prevention. Natural polysaccharides demonstrate immense potential in healthcare sensors by leveraging their superior biocompatibility, biodegradability, environmental sustainability, as well as diverse structural designs and surface functionalities. This review begins by introducing a variety of natural polysaccharides, including cellulose, alginates, chitosan, hyaluronic acid, and starch, and analyzing their structural and functional distinctions, which offer extensive possibilities for sensor design and construction. Further, we summarize several principal sensing mechanisms, such as piezoresistivity, piezoelectricity, capacitance, triboelectricity, and hygroelectricity, which provide a theoretical and technological foundation for developing high-performance healthcare sensing devices. Additionally, the review discusses the most recent applications of natural polysaccharide-based sensors in diverse healthcare contexts, including human body motion tracking, respiratory and heartbeat monitoring, electrophysiological signal recording, body temperature variation detection, and biomarker analysis. Finally, prospective development directions are proposed, such as the integration of artificial intelligence for real-time data analysis, the design of multifunctional devices that combine sensing with therapeutic functionalities, and advancements in remote monitoring and smart wearable technologies. This review aims to provide valuable insights into the development of next-generation healthcare sensors and propose novel research directions for personalized medicine and remote health management.

Biomaterials for reliable wearable health monitoring: Applications in skin and eye integration

Recent advancements in biomaterials have significantly impacted wearable health monitoring, creating opportunities for personalized and non-invasive health assessments. These developments address the growing demand for customized healthcare solutions. Durability is a critical factor for biomaterials in wearable applications, as they must withstand diverse wearing conditions effectively. Therefore, there is a heightened focus on developing biomaterials that maintain robust and stable functionalities, essential for advancing wearable sensing technologies. This review examines the biomaterials used in wearable sensors, specifically those interfaced with human skin and eyes, highlighting essential strategies for achieving long-lasting and stable performance. We specifically discuss three main categories of biomaterials-hydrogels, fibers, and hybrid materials-each offering distinct properties ideal for use in durable wearable health monitoring systems. Moreover, we delve into the latest advancements in biomaterial-based sensors, which hold the potential to facilitate early disease detection, preventative interventions, and tailored healthcare approaches. We also address ongoing challenges and suggest future directions for research on material-based wearable sensors to encourage continuous innovation in this dynamic field.

Hydrogen bonds-pinned entanglement double network alginate hydrogel for electrical application

In response to prevailing challenges encountered in electrical applications, including insufficient mechanical strength, subpar tensile properties, and limited adaptability to dynamic motion environments, we engineered a pioneering hydrogel adhesive. Simultaneously, we presented a novel interpretation of the application of ZnO in hydrogels. Our innovative approach entailed the intertwining of polyvinyl alcohol (PVA) and flexible sodium alginate (SA) double networks (DN) through cross-linking mechanisms, resulting in the formation of a hydrogen-bonding pinned DN hydrogel. This groundbreaking design substantially amplified the cohesive and adhesive properties of the hydrogel, while the incorporation of zinc oxide (ZnO) through modification served to enhance its electrical conductivity. Our hydrogel sensor demonstrated exceptional capabilities in monitoring human motion, adeptly meeting the demands of diverse motion scenarios. Furthermore, meticulous consideration had been given to the influence of perspiration on sensor performance, rendering our sensor exceptionally well-suited for real-world applications.

A self-healing, long-lasting adhesive, lignin-based polyvinyl alcohol organo-hydrogel for strain-sensing applications

Hydrogel-based flexible sensors have garnered considerable interest in the fields of soft electronics, robotics, and human-machine interfaces. For better practical applications, integrating multiple properties-such as self-adhesive, anti-freeze, anti-volatile, self-healing, and antibacterial-into a single gel for flexible sensors remains a challenge. In this paper, a multifunctional lignin-based polyvinyl alcohol gel, containing dynamic covalent bonds, hydrogen bonds, and coordination bonds, is constructed by a simple one-pot method, in which ethylene glycol/water chosen as a binary solvent and KI as a conductive medium. The resulting organogel exhibits self-healing, long-lasting adhesion, UV shielding, antibacterial properties, excellent frost resistance (-20 °C), and volatile resistance properties. In addition, the organogel-based sensor demonstrates satisfactory sensitivity in detecting joint movements and facial expressions. This study provides a new strategy for developing a versatile flexible sensor through the introduction of renewable and bio-based lignin, promising applications in the fields of wearable electronics.

Fully Physically Crosslinked Hydrogel with Ultrastretchability, Transparency, and Freezing-Tolerant Properties for Strain Sensor

Nowadays, conductive hydrogels show significant prospects as strain sensors due to their good stretchability and signal transduction abilities. However, traditional hydrogels possess poor anti-freezing performance at low temperatures owing to the large number of water molecules, which limits their application scope. To date, constructing a hydrogel-based sensor with balanced stretchability, conductivity, transparency, and anti-freezing properties via simple methods has proven challenging. Here, a fully physically crosslinked poly(hydroxyethyl acrylamide)-glycerol-sodium chloride (PHEAA-Gl-NaCl) hydrogel was obtained by polymerizing hydroxyethyl acrylamide in deionized water and then soaking it in a saturated NaCl solution of glycerol and water. The PHEAA-Gl-NaCl hydrogel had good transparency (~93%), stretchability (~1300%), and fracture stress (~287 kPa). Owing to the presence of glycerol and sodium chloride, the PHEAA-Gl-NaCl hydrogel had good anti-freezing properties and conductivity. Furthermore, the PHEAA-Gl-NaCl hydrogel-based strain sensor possessed good sensitivity and cyclic stability, enabling the detection of different human motions stably and in a wide temperature range. Based on the above characteristics, the PHEAA-Gl-NaCl hydrogel has broad application prospects in flexible electronic materials.

Effects of Enteromorpha prolifera sulfated polysaccharide and aluminium ion addition on the multifunctional property of conductive hydrogel for wearable strain sensing

Although introducing Enteromorpha prolifera sulfated polysaccharide (SPEP) enhances the mechanical properties of hydrogels significantly, little is known about the effects of polysaccharide and ion addition on morphological and physicochemical properties of conductive hydrogel. Therefore, the Poly (acrylic acid)/SPEPn/Al3+m (PAA/SPEPn/Al3+m) hydrogels with different SPEP and Al3+ addition were synthesized by simple one-pot method. The porosity, tensile strength, and swelling ration increased, while compressive strength, elongation at break, self-healing, self-adhesion properties increased first and then decreased as SPEP addition increased from 0 % to 3.80 %. The Al3+ addition increased from 0.08 % to 0.30 %, both tensile and compressive strength increased first and then decreased, while elongation at break kept increasing. Unexpectedly, both increasing SPEP and Al3+ addition reduced the electrical conductivity, while SPEP increased the gauge factor of hydrogel. The hydrogel exhibited optimal comprehensive properties when SPEP and Al3+ addition were 2.31 % and 0.24 %, respectively. The PAA/SPEP2.31%/Al3+0.24% hydrogel showed high tensile strength (107.60 kPa), elongation at break (2426.67 %), strain self-healing rate (81.87 %), adhesion strength (21.61 kPa), and conductivity (3.60 S/m). Overall, the properties of PAA/SPEPn/Al3+m hydrogels can be regulated through tailoring SPEP and Al3+ addition, which can be used as on-demand strategy to improve the performance of PAA/SPEPn/Al3+m hydrogels for each application.

A hydrogel sensor based on cellulose nanofiber/polyvinyl alcohol with colorimetric-fluorescent bimodality for non-invasive detection of urea in sweat

The concentration of urea in sweat serves as a valuable indicator of an individual's overall health. In this study, we present a novel hydrogel sensor (BAF-CPu), based on cellulose nanofiber and polyvinyl alcohol, designed to achieve non-invasive in situ and highly sensitive detection of urea in sweat by combining the dual-mode response of colorimetric and ratiometric fluorescence techniques. The bright red fluorescent gold‑copper bimetallic nanoclusters and green fluorescent fluorescein isothiocyanate-modified cellulose nanofibers endowed BAF-CPu with proportional fluorescence responsive properties. Under the catalytic action of urease, the hydrolysis of urea raises the pH, resulting in diminished red fluorescence along with enhanced green fluorescence, and the fluorescence color of BAF-CPu changes from red to green. Moreover, BAF-CPu hydrogel encapsulates pH-responsive bromothymol blue (BTB), which changes from yellow to blue in the presence of urea. Importantly, BAF-CPu absorbs sweat by adhering directly to the skin surface, avoiding the complicated sampling process and improving the maneuverability of the detection process. With both ratiometric fluorescence and colorimetric modes, BAF-CPu is not only able to detect sweat in situ, but also can reduce the interference of the complex sweat environment on the urea detection, and realize the high sensitivity detection of urea in sweat.

Recent Advances of Stretchable Nanomaterial-Based Hydrogels for Wearable Sensors and Electrophysiological Signals Monitoring

Electrophysiological monitoring is a commonly used medical procedure designed to capture the electrical signals generated by the body and promptly identify any abnormal health conditions. Wearable sensors are of great significance in signal acquisition for electrophysiological monitoring. Traditional electrophysiological monitoring devices are often bulky and have many complex accessories and thus, are only suitable for limited application scenarios. Hydrogels optimized based on nanomaterials are lightweight with excellent stretchable and electrical properties, solving the problem of high-quality signal acquisition for wearable sensors. Therefore, the development of hydrogels based on nanomaterials brings tremendous potential for wearable physiological signal monitoring sensors. This review first introduces the latest advancement of hydrogels made from different nanomaterials, such as nanocarbon materials, nanometal materials, and two-dimensional transition metal compounds, in physiological signal monitoring sensors. Second, the versatile properties of these stretchable composite hydrogel sensors are reviewed. Then, their applications in various electrophysiological signal monitoring, such as electrocardiogram monitoring, electromyographic signal analysis, and electroencephalogram monitoring, are discussed. Finally, the current application status and future development prospects of nanomaterial-optimized hydrogels in wearable physiological signal monitoring sensors are summarized. We hope this review will inspire future development of wearable electrophysiological signal monitoring sensors using nanomaterial-based hydrogels.

Temperature-Tolerant Versatile Conductive Zwitterionic Nanocomposite Organohydrogel toward Multisensory Applications

Conductive hydrogels (CHs) are emerging materials for next generation sensing systems in flexible electronics. However, the fabrication of competent CHs with excellent stretchability, adhesion, self-healing, photothermal conversion, multisensing, and environmental stability remains a huge challenge. Herein, a nanocomposite organohydrogel with the above features is constructed by in situ copolymerization of zwitterionic monomer and acrylamide in the existence of carboxylic cellulose nanofiber-carrying reduced graphene oxide (rGO) plus a solvent displacement strategy. The synergy of abundant dipole-dipole interactions and intermolecular hydrogen bonds enables the organohydrogel to exhibit high stretchability, strong adhesion, and good self-healing. The presence of glycerol weakens the formation of hydrogen bonds between water molecules, endowing the organohydrogel with excellent environmental stability (-40 to 60 °C) to adapt to different application scenarios. Importantly, the multimodal organohydrogel presents excellent sensing behavior, including a high gauge factor of 16.3 at strains of 400-1440% and a reliable thermal coefficient of resistance (-4.2 °C-1) over a wide temperature widow (-40 to 60 °C). Moreover, the organohydrogel displays a highly efficient and reliable photothermal conversion ability due to the favorable optical absorbing behavior of rGO. Notably, the organohydrogel can detect accurate human activities at ambient temperature, demonstrating potential applications in flexible intelligent electronics.

Extreme condition-tolerant stretchable flexible supercapacitor and triboelectric nanogenerator based on carrageenan-enhanced gel for energy storage, energy collection and self-powered sensing

As flexible electronics devices for energy storage, mechanical energy collection and self-powered sensing, stretchable flexible supercapacitor and triboelectric nanogenerator (TENG) have attracted extensive attention. However, it is difficult to satisfy the requirements of high safety and resistance to extreme conditions. Dual roles of mechanical and electrical enhancement of inorganic salt are put forward, and a carrageenan (CG) enhanced poly (N-hydroxyethyl acrylamide)/CG/lithium chloride/glycerol (PCLG) conductive gel is prepared by designing hydrogen bonding self-crosslinking and chain entanglement. A high concentration and rapid deposition strategy is proposed to prepare a PCLG gel-based stretchable flexible all-in-one supercapacitor for energy storage, and a single electrode PCLG gel-based TENG is designed for mechanical energy collection, self-powered strain and tactile sensing. The supercapacitor has high capacitance, excellent cycling stability. The TENG possesses efficient energy harvesting with high and stable output voltage and power density, and sensitive and stable self-powered strain and tactile sensing without external power supply. Even under extreme conditions such as low temperatures, self-healing after damage, prolonged placement, deformation, post-deformation, multiple continuous work, pinprick and burning, the supercapacitor and TENG still have excellent properties. Therefore, we provide novel ideas to design flexible supercapacitor and TENG used under extreme conditions for future wearable electronics.

Humidity Adaptive Antifreeze Hydrogel Sensor for Intelligent Control and Human-Computer Interaction

Conductive hydrogels have emerged as ideal candidate materials for strain sensors due to their signal transduction capability and tissue-like flexibility, resembling human tissues. However, due to the presence of water molecules, hydrogels can experience dehydration and low-temperature freezing, which greatly limits the application scope as sensors. In this study, an ionic co-hybrid hydrogel called PBLL is proposed, which utilizes the amphoteric ion betaine hydrochloride (BH) in conjunction with hydrated lithium chloride (LiCl) thereby achieving the function of humidity adaptive. PBLL hydrogel retains water at low humidity (<50%) and absorbs water from air at high humidity (>50%) over the 17 days of testing. Remarkably, the PBLL hydrogel also exhibits strong anti-freezing properties (-80 °C), high conductivity (8.18 S m-1 at room temperature, 1.9 S m-1 at -80 °C), high gauge factor (GF approaching 5.1). Additionally, PBLL hydrogels exhibit strong inhibitory effects against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), as well as biocompatibility. By synergistically integrating PBLL hydrogel with wireless transmission and Internet of Things (IoT) technologies, this study has accomplished real-time human-computer interaction systems for sports training and rehabilitation evaluation. PBLL hydrogel exhibits significant potential in the fields of medical rehabilitation, artificial intelligence (AI), and the Internet of Things (IoT).

Liquid-free ionic conductive elastomers with high mechanical properties and ionic conductivity for multifunctional sensors and triboelectric nanogenerators

Liquid-free ionic conductive elastomers (ICEs) are ideal materials for constructing flexible electronic devices by avoiding the limitations of liquid components. However, developing all-solid-state ionic conductors with high mechanical strength, high ionic conductivity, excellent healing, and recyclability remains a great challenge. Herein, a series of liquid-free polyurethane-based ICEs with a double dynamic crosslinked structure are reported. As a result of interactions between multiple dynamic bonds (multi-level hydrogen bonds, disulfide bonds, and dynamic D-A bonds) and lithium-oxygen bonds, the optimal ICE exhibited a high mechanical strength (1.18 MPa), excellent ionic conductivity (0.14 mS cm-1), desirable healing capacity (healing efficiency >95%), and recyclability. A multi-functional wearable sensor based on the novel ICE enabled real-time and rapid detection of various human activities and enabled recognizing writing signals and encrypted information transmission. A triboelectric nanogenerator based on the novel ICE exhibited an excellent open-circuit voltage of 464 V, a short-circuit current of 16 μA, a transferred charge of 50 nC, and a power density of 720 mW m-2, enabling powering of small-scale electronic products. This study provides a feasible strategy for designing flexible sensor products and healing, self-powered devices, with promising prospects for application in soft ionic electronics.

Multiple physical crosslinked highly adhesive and conductive hydrogels for human motion and electrophysiological signal monitoring

Hydrogel-based flexible electronic devices serve as a next-generation bridge for human-machine interaction and find extensive applications in clinical therapy, military equipment, and wearable devices. However, the mechanical mismatch between hydrogels and human tissues, coupled with the failure of conformal interfaces, hinders the transmission of information between living organisms and flexible devices, which resulted in the instability and low fidelity of signals, especially in the acquisition of electromyographic (EMG) and electrocardiographic (ECG) signals. In this study, we designed an ion-conductive hydrogel (ICHgel) utilizing multiple physical interactions, successfully applied for human motion monitoring and the collection of epidermal physiological signals. By incorporating fumed silica (F-SiO2) nanoparticles and calcium chloride into an interpenetrating network (IPN) composed of polyvinyl alcohol (PVA) and polyacrylamide (AAm)/acrylic acid (AA) chains, the ICHgel exhibited exceptional tunable stretchability (>1450% strain) and conductivity (10.58 ± 0.85 S m-1). Additionally, the outstanding adhesion of the ICHgel proved to be a critical factor for effective communication between epidermal tissues and flexible devices. Demonstrating its capability to acquire stable electromechanical signals, the ICHgel was attached to different parts of the human body. More importantly, as a flexible electrode, the ICHgel outperformed commercial Ag/AgCl electrodes in the collection of ECG and EMG signals. In summary, the synthesized ICHgel with its outstanding conformal interface capabilities and mechanical adaptability paves the way for enhanced human-machine interaction, fostering the development of flexible electronic devices.

A nanocomposite hydrogel loaded with Ag nanoparticles reduced by aloe vera polysaccharides as an antimicrobial multifunctional sensor

Developing high-performance hydrogels with anti-freeze, and antimicrobial properties is crucial for the practical application of flexible sensors. In this study, we prepared silver nanoparticles (AgNPs) with aloe polysaccharide (AP) as a reducing agent. Then, the AP/AgNPs were added to a system of polyvinyl alcohol and borax crosslinked in water/glycerol to obtain a multifunctional conductive hydrogel. The incorporated AgNPs improved the conductivity (0.39 S/m) and mechanical properties (elongation at break: 732.9 %, fracture strength: 1267.6 kPa) of the hydrogel. In addition, resultant hydrogel exhibited potential for sensing strain, temperature, and humidity. When used as a strain sensor, the hydrogel system exhibited low detection limit (0.1 %), and fast response (0.08 s). The resistance of the hydrogel decreased with an increase in the absorbed moisture content, enabling humidity detection (25-95 %) to monitor breathing status. As a temperature sensor, the hydrogel supported a wide detection range (-50 to +90 °C) and sensitivity (-30-0 °C, temperature coefficient of resistance (TCR) = -5.64 %/°C) to detect changes in the ambient temperature. This study proposes a simple method for manufacturing multifunctional hydrogel sensors, which broadens their application prospects in wearable sensing and electronic products.

Anti-freezing hydrogel regulated by ice-structuring proteins/cellulose nanofibers system as flexible sensor for winter sports

Conductive hydrogels are widely used as sensors in wearable devices. However, hydrogels cannot endure harsh low-temperature environments. Herein, a new regulatory system based on natural ice-structuring proteins (ISPs) and cellulose nanofibers (CNFs) is introduced into hydrogel network consisting of chemically crosslinked network of copolymerized acrylamide and 2-acrylamide-2-methylpropanesulfonic acid, and physically crosslinked polyvinyl alcohol chains, affording an anti-freezing hydrogel with high conductivity (2.63 S/m). These hydrogels show excellent adhesion behavior to various matrices (including aluminum, glass, pigskin, and plastic). Their mechanical properties are significantly improved with the increase in CNF content (tensile strength of 106.4 kPa, elastic modulus of 133.8 kPa). In addition, ISPs inhibit the growth of ice. This endows the hydrogels with anti-freezing property and allows them to maintain satisfactory mechanical properties, conductivity and sensing properties below zero degrees. Moreover, this hydrogel shows high sensitivity to tensile and compressive deformation (GF = 5.07 at 600-800 % strain). Therefore, it can be utilized to develop strain-type pressure sensors that can be attached directly to human skin for detecting various body motions accurately, reliably, and stably. This study proposes a simple strategy to improve the anti-freezing property of hydrogels, which provides new insights for developing flexible hydrogel electronic devices for application in winter sports.

Highly Sensitive and Wide Detection Range Thermoplastic Polyurethane/Graphene Nanoplatelets Multifunctional Strain Sensor with a Porous and Crimped Network Structure

High-performance flexible strain sensors have tremendous potential applications in wearable devices and health monitoring. However, developing a flexible strain sensor with high sensitivity over a wide strain range remains a significant challenge. In this study, a fibrous membrane with a porous and crimped structure was designed as the substrate material for TPU/GNPs flexible strain sensors. This structural design effectively balances sensitivity with the strain range. The TPU-PEO fibrous membrane prepared using electrospinning with water washing, resulted in a porous fibrous membrane with a TPU framework. Subsequently, the fibrous membrane was subjected to anhydrous ethanol stimulation to obtain a porous and crimped network structure. GNPs were modified on the TPU fibrous membrane through ultrasonic treatment. The produced flexible strain sensor exhibited high sensitivity (GF = 4047.5) within a large strain range (350%) and demonstrated excellent sensing performance, stability, and durability (>10,000 cycles). It not only captured basic movements but also efficiently recognized and measured bending angles, enabling a more sophisticated human-machine interaction experience. This advancement opens up possibilities for future intelligent wearable technology and human-machine interaction, contributing to the evolution of these fields.

Fabrication of anti-freezing and self-healing nanocomposite hydrogels based on phytic acid and cellulose nanocrystals for high strain sensing applications

For hydrogel-based flexible sensors, it is a challenge to enhance the stability at sub-zero temperatures while maintaining good self-healing properties. Herein, an anti-freezing nanocomposite hydrogel with self-healing properties and conductivity was designed by introducing cellulose nanocrystals (CNCs) and phytic acid (PA). The CNCs were grafted with polypyrrole (PPy) by chemical oxidation, which were used as the nanoparticle reinforcement phase to reinforce the mechanical strength of hydrogels (851.8%). PA as a biomass material could form strong hydrogen bond interactions with H2O molecules, endowing hydrogels with prominent anti-freezing properties. Based on the non-covalent interactions, the self-healing rate of the hydrogels reached 92.9% at -15 °C as the content of PA was 40.0 wt%. Hydrogel-based strain sensors displayed high sensitivity (GF = 0.75), rapid response time (350 ms), good conductivity (3.1 S m-1) and stability at -15 °C. Various human movements could be detected by using them, including small (smile and frown) and large changes (elbow and knee bending). This work provides a promising method for the development of flexible wearable sensors that work stably in frigid environments.