A supersensitive wearable sensor constructed with PDMS porous foam and multi-integrated conductive pathways structure

In recent years, wearable multifunctional strain sensors have attracted attention for their promising applications in wearable electronics and portable devices. To achieve a high-performance wearable strain sensor with a wide sensing range and high gauge factor (GF), wisely choosing appropriate conductive materials and a rational structural design is essential. Herein, we develop a supersensitive sensor that contains one-dimensional conductive material CNT and two-dimensional material MXene built on a PDMS porous foam that is made based on a sugar template. The one-dimensional carbon nanotube (CNT) functionalizes as a conductive scale layer through solvent swelling and evaporation on the surface of the PDMS skeleton. The two-dimensional MXene is applied on top of the CNT layer to form final conductive pathways. The PDMS/CNT@MXene (PCM) sensor has a wide sensing range (150%), high sensitivity (GF = 26438), rapid response speed (response/recovery time of 60/71 ms), and exceptional durability (>1000 cycles) owing to its unique porous structure with scale layers and graded fracture of conductive pathways. Moreover, the PCM sensor is capable of monitoring subtle and significant human activities and is used for wireless sensing and medical diagnostics, even for solvent identification. The superior performance of the PCM sensor provides vast application potential in human movement, health monitoring, and warning devices.     

Highly sensitive flexible strain sensor based on carbon nanotube/styrene butadiene styrene@ thermoplastic polyurethane fiber with a double percolated structure

The combination of a high sensitivity and a wide strain detection range in conductive polymer composites-based flexible strain sensors is still challenging to achieve. Herein, a double-percolation structural fiber strain sensor based on carbon nanotubes (CNT)/styrene butadiene styrene (SBS)@thermoplastic polyurethane (TPU) composite was fabricated by a simple melt mixing and fused filament fabrication strategy, in which the CNT/SBS and TPU were the conductive and insulating phases, respectively. Compared with the sensor without the double percolated structure, the CNT/SBS@TPU sensor achieved a lower percolation threshold (from 2.0 to 0.5 wt%, a reduction of 75%), and better electrical and sensing performance. It is shown that the strain detection range of the CNT/SBS@TPU sensor increases with increasing CNT loading. An opposite trend was observed for the sensitivity. The 1%-CNT/SBS@TPU sensor exhibited a high conductivity (1.08 × 10⁻³ S/m), high sensitivity (gauge factor of 2.65 × 10⁶ at 92% strain), wide strain detection range (0.2%–92% strain), high degree of linearity (R² = 0.954 at 0–10% strain), broad monitoring frequencies (0.05–0.5 Hz), and excellent stability (2000 cycles). Moreover, the CNT/SBS@TPU sensor was shown to successfully monitor a range of human physiological activities and to be capable of tactile perception and weight distribution sensing.     

A novel graphene-like titanium carbide MXene/Au–Ag nanoshuttles bifunctional nanosensor for electrochemical and SERS intelligent analysis of ultra-trace carbendazim coupled with machine learning

A new bifunctional intelligent nanosensing platform based on graphene-like titanium carbide MXene (Ti₂C MXene)/Au–Ag nanoshuttles (NSs) for both electrochemical and surface-enhanced Raman scattering (SERS) intelligent analysis of ultra-trace carbendazim (CBZ) residues in tea and rice coupled with machine learning (ML) was successfully designed. Ti₂C MXene was synthesized by selectively etching Al layers of Ti₂AlC with hydrofluoric acid and high-temperature calcination. Ti₂C MXene/Au–Ag NSs prepared by the ultrasonic dispersion of graphene-like Ti₂C MXene into Au–Ag NSs solution under dark conditions displayed large and rough surface, enhanced conductivity, excellent electrochemical response, prominent Raman enhancement, and high stability. The ML via different algorithms such as artificial neural network, support vector machine, and relevance vector machine (RVM) for the intelligent analysis of CBZ was contrasted and discussed. RVM displayed more superiority for the electrochemical analysis of CBZ in a wide linear range of 0.006 – 9.8 μM with low limit of detection (LOD) of 0.002 μM and SERS detection of CBZ in the wide linear range of 0.033 – 10 μM with low LOD of 0.01 μM. This will provide a new bifunctional intelligent sensing platform via different ML algorithms for improving accuracy of sensor via mutual verification of two or more methods of detection and a new bifunctional nanosensing platform based on the development of graphene-like nanohybrid for food and agro-products safety.     

Flexible and high-sensitivity piezoresistive sensor based on MXene composite with wrinkle structure

Due to the portability, good flexibility and excellent sensing performance, flexible piezoresistive sensors have received great attention in the field of transient electronic skin, intelligent robots and human-machine interaction. However, achieving both high sensitivity and wide sensing range by low-cost and large-scale method still remains a key challenge for developing high performance piezoresistive sensors. Here, a flexible and highly sensitive piezoresistive sensor was designed and realized by combining the 2D MXene material with wrinkle structure. The MXene composite based sensor with wrinkle structure was fabricated by spraying the active material onto the surface of a pre-stretched polyacrylate tape, which is facile, efficient and low-cost. The MXene composite based sensor demonstrates high sensitivity (148.26 kPa⁻¹), wide pressure range (up to 16 kPa), short response time (120 ms) and excellent durability (>13000 cycles). Moreover, benefiting from the extraordinary sensing performance and flexibility, the sensor can detect human physiological signals, monitor intelligent robot postures and map spatial pressure distributions, thus exhibiting great potential in physiological analysis systems, humanoid robotics and biomedical prostheses.     

Multifunctional MXene/CNT-based layered film for icing detection,anti-icing,and deicing application

Icing phenomenon usually happens in our daily life, especially in the cold winter or in high altitude areas, which makes us feel inconvenient and greatly threats some fields such as civil aviation or the manufacturing industry. In this study, a multifunctional film with properties of icing detection, anti-icing and deicing was fabricated. One-dimensional material carbon nanotube (CNT) and two-dimensional material Ti₃C₂T_x MXene were combined by two-step vacuum filtration. Polydimethylsiloxane (PDMS) as the flexible hydrophobic materials was then used to encapsulate layered film. Additionally, PDMS curing process on the sandpaper could make the surface of MXene/CNT layered film possess micro-structures. The low surface energy material PDMS and rough surface structures endow MXene/CNT layered film with good water-repellency. Compared with pure PDMS film (103°), the contact angle of MXene/CNT layered film surface reaches 128°. The result exhibits that a waterdrop(100uL) on the layered film surface takes 1425s to be frozen, which takes longer time than glass and pure PDMS. Additionally, excellent sensibility of the layered film could be used to detect icing phenomenon. The result manifests that gauge factor (GF) of MXene/CNT film reaches 15051 so that different icing stages could be identified by layered film clearly. MXene/CNT layered film possesses good electric heating and photo-thermal properties. The result shows that surface temperature can reach 89 °C with the 2.5 V voltage supply, and temperature reaches 95 °C through the radiation of near-infrared lamp as well. The dual-driven heating of MXene/CNT layered film shows the ability of deicing. 1000 mg ice just takes 223s to be melted entirely by 2.5 V input voltage, and 269s by radiation of 200 mW/cm², respectively. The multifunctional MXene/CNT based layered film prepared by a simple fabrication method that integrates hydrophobicity, dual-driven heating, and sensibility together, which shows potential application in icing detection, anti-icing, and deicing.     

Blends of thermoplastic polyurethane (TPU) and polydimethyl siloxane rubber (PDMS), part-I: assessment of compatibility from torque rheometry and mechanical properties

Thermoplastic polyurethane (TPU) and polydimethyl siloxane rubber (PDMS) are two major polymers used extensively for biomedical applications. Blending of these polymers combines the superior mechanical properties, abrasion resistance, solvent resistance and aging resistance of TPU with chemical stability, inertness, flexibility and biocompatibility of PDMS. In the present investigation, an 80:20 blend of TPU and PDMS was selected for the preparation of an in situ compatibilized blend using ethylene methyl acrylate copolymer (EMA) as the compatibilizer. Effect of EMA on blends of ester type and ether type TPU with PDMS was studied. From the results obtained from torque rheometry, mechanical property evaluation, fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and scanning electron microscopy (SEM), it was concluded that 5 wt% of compatibilizer effectively compatibilized an 80:20 blend of ester type TPU and PDMS, whereas similar blend of ether type TPU required only 2 wt% compatibilizer.     

Enhanced sensing performance of flexible strain sensors prepared from biaxially stretched carbon nanotubes/polydimethylsiloxane nanocomposites

Flexible strain sensors from biaxially stretched carbon nanotubes (CNTs)/polydimethylsiloxane (PDMS) nanocomposites are fabricated in this study. It is shown that biaxial stretching promotes the homogeneous distribution and alignment of CNTs in the stretching plane, improving the sensing performance of the strain sensors. The optimized stretching ratios (SRs) of CNT/PDMS nanocomposites are determined. Compared to an unstretched CNT/PDMS-1.0 sensor (gauge factor [GF] value = 0.73, detectable range from 0 to 60%), the 1.5 wt% CNT/PDMS-1.5 sensor (SR = 1.5) exhibits enhanced strain sensitivity (GF = 2.8), a wider detectable range (0–370%) and better performance stability. The GF values of CNT/PDMS-2.0 and CNT/PDMS-2.5 sensors with SRs of 2.0 and 2.5, respectively, were 1.18 and 1.06, respectively, due to more significant conductive network reconstruction in the process of applying strain, leading to a decreasing GF. The possibility of sensors in the application of wearable electronic components is also demonstrated. The sensor shows a clear and stable signal output when different strain modes are applied, such as tensile, compressive, bending, and twisting.     

Enhanced Strain Sensing Performance of Polymer/Carbon Nanotube‐Coated Spandex Fibers via Noncovalent Interactions

Over the past decade, flexible strain sensors have been of tremendous interest due to their wide application in robotics, medical diagnostics, human motion detection, and healthcare. Herein, a fiber strain sensor is fabricated by continuously coating a layer of ultrathin multi‐walled carbon nanotube (MWCNT)/thermoplastic polyurethane (TPU) nanocomposites onto the surface of commercial spandex fiber. The effect of noncovalent functionalization of MWCNTs using 1‐pyrenecarboxylic acid (PCA) on the electrical conductivity as well as the sensing performance of the fiber sensor is investigated. The low‐cost strain sensor possesses a large workable strain (up to 200% strain), high sensitivity (gauge factor is 14 191.5 under 170–200% strain), and excellent stability (up to 1000 cycles), and regular signal responses within a wide measuring frequency range of 0.01–1 Hz are achieved with the introduction of PCA via enhanced nanotube dispersion and polymer–nanofiller interactions. Additionally, the resistance response to strain is fitted with a model based on tunneling theory to understand the sensing mechanism, and to prove that the fitted results are in agreement with the experimental results. Furthermore, the developed sensor is successfully applied in human motion detection, such as joint movement, facial microexpressions, and speech recognition.     

Strategy for improving the capacity and rate performance of LiNixCoyMn1−x−y electrode using Ti3C2Tx MXene additives

With the expanding range of applications for lithium-ion batteries, a great deal of research is being conducted to improve their capacity, stability, and charge/discharge rates. This study was performed to investigate the effects of MXene, which has a large surface area and metallic conductivity, as a conductive additive to the cathode, on electrochemical performance. The two-dimensional material MXene constructs a conductive network with zero-dimensional carbon black in plane-to-point mode to improve conductivity and contact area with active materials, thereby facilitating fast charge transfer. The conductive network reduces the internal resistance and polarization of the cathode and aids the diffusion of electrons. The electrode containing an appropriate amount of MXene showed improved rate performance, high discharge capacity (123.9 mAh g⁻¹ at 4 C), and excellent cycle stability at a high scan rate (125.8 mAh g⁻¹ at 2 C after 150 cycles) compared to pristine electrodes. Based on these results, Ti₃C₂T_x MXene is a promising conductive additive in the battery field.     

MXene Reinforced PAA/PEDOT:PSS/MXene Conductive Hydrogel for Highly Sensitive Strain Sensors

Conductive hydrogel has a vital application prospect in flexible electronic fields such as electronic skin and force sensors. Developing conductive hydrogel with significant toughness and high sensitivity is urgently needed for application research. In this work, a strong and sensitive strain sensor based on conductive hydrogel is demonstrated by introducing MXene (Ti3C2Tx) into the micelle crosslinked polyacrylic acid (PAA)/poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) hydrogel network. The functional polymer micelle crosslinkers can dissipate external stress by deformation, endowing the hydrogel with high strength. The combination of MXene both improves the polymer network structure and the conductive pathways, further enhancing the mechanical properties and sensing performance. Resultantly, the flexible strain sensor base on PAA/PEDOT:PSS/MXene conductive hydrogel exhibits excellent sensing performance with a high gauge factor of 20.86, a large strain detection range of 1000%, as well as good adhesion on different interfaces. Thus, it can be used to monitor various movements of the human body and identify all kinds of handwriting, showing great potential into wearable electronics.     

Room temperature NH3 gas sensor based on PMMA/RGO/ZnO nanocomposite films fabricated by in-situ solution polymerization

Effective detection of ammonia gas is of great importance due to its detrimental effects on human health, environment, and ecosystem. High-performance composite gas sensors are vital in accomplishing this goal. Herein, we investigate the performance of an ammonia (NH₃) gas sensor fabricated via dip-coating the silver interdigitated electrode for PMMA/RGO/ZnO (PRZ) nanocomposite solution with acetone as a solvent. The PRZ ternary nanocomposite was synthesized using the in-situ solution polymerization method and the resistive properties of the films assembled on the interdigitated electrode were analyzed, with respect to the fixed and varying ammonia gas concentrations, using LCR meter. When the sensor is operated in the controlled chamber containing ammonia gas at room temperature, the sensor responds rapidly to ammonia with a fast recovery of 13.02 s at a gas concentration of 350 ppm. The PRZ sensor exhibits high sensing percentage response (527%), excellent repeatability (four times), high sensitivity at low concentrations (less than 10 ppm), swift response and recovery times (1.94 s/13.02 s), and long-term stability (up to 90 days) with fluctuation of 3.2%, which signifies PRZ composite as a potential material for ammonia gas sensor. Aspects such as simplicity of the synthesis process and fabrication, excellent sensing performance, as well as fast response-recovery time at a particular gas concentration are noteworthy in this study. These features can be utilized for the detection of ammonia gas in chemical and biological fields.     

Microstructure Engineering of Stretchable Resistive Strain Sensors with Discrimination Capabilities in Transverse and Longitudinal Directions

Featuring simple device structure, high sensitivity, and excellent reliability, stretchable resistive sensors have developed rapidly due to the high demand for flexible and wearable electronics. Nevertheless, it remains critically challenging to evaluate external stimuli using one simple device for diverse application scenarios. Here, a microstructure is engineered for a stretchable sensor by a facile replication/transferring and a prestretching/releasing process, enabling the device to have discrimination capabilities in the transverse direction (X-axis) and longitudinal direction (Y-axis). Consisting of silver nanowires (Ag NWs)/transition metal carbides (MXene)/poly(3,4-ethylenedioxythiophene):poly (styrene-sulfonate) (PEDOT:PSS) conducting layer and polydimethylsiloxane (PDMS)/Ecoflex elastomer, the microstructured sensor has a broad strain range of 120% along the X-axis and a large gauge factor (GF) of 37.44 along the Y-axis, and shows good stability during 1000 stretching/releasing cycles along two directions, indicating the excellent interfacial connection between the sensing layer and elastomer. As a result, taking advantages of distinct performance along two directions, the proposed stretchable sensor is demonstrated to monitor a variety of human movements and physical stimuli as a wearable and flexible device, revealing its promising potential in diverse application scenarios.     

Synthesis and characterization of layered Nb2C MXene/ZnS nanocomposites for highly selective electrochemical sensing of dopamine

MXenes, due to their exceptional properties, are tagged as materials of future in the field of two dimensional (2D) materials. Niobium carbide (Nb₂C) is an important member of MXene family having vast application in the field of lithium ion batteries and supercapacitors. However, its applications in the field of sensing have not been explored yet. This research work reports the synthesis and application of Nb₂C/ZnS nanocomposite for the sensing of dopamine (DA) for the first time. The etching of Nb₂C from parent MAX phase (Nb₂AlC) was performed at 55 °C. The application of Nb₂C electrode for the electrochemical sensing of DA was employed through differential pulse voltammetry (DPV). Zinc sulphide (ZnS) nanoparticles were synthesized hydrothermally to enhance the electrochemical properties of Nb₂C. The characterization of these prepared samples was done with the help XRD, SEM, EDS, and of FTIR spectroscopy. The MXene-ZnS nanocomposite modified glassy carbon electrode (GCE) proved to be a very effective electrode material to detect dopamine electrochemically with a wide linear detection range of 0.09–0.82 mM, a very low detection limit of 1.39 μM and excellent sensitivity of 12.1 μAμM^-1. The modified glassy carbon electrode also proved to be exceptionally selective towards dopamine in the presence of interfering agents like ascorbic acid, citric acid and glucose.     

A dynamic supercritical carbon dioxide foaming method for fabricating wrinkled surface to enhance triboelectric nanogenerator performance

Triboelectric nanogenerator (TENG) is a promising energy harvester to overcome the energy depletion issue. The surface structure has been considered as an effective way to enhance the triboelectric performance. Herein, a dynamic supercritical carbon dioxide (scCO₂) foaming method, which introduced a scCO₂ flow field during scCO₂ saturation, was proposed to fabricate thermoplastic polyurethane (TPU) foams with surface wrinkly structures. The size of the surface wrinkles could be regulated in the range of 1.8–10 μm by varying the foaming pressure. The surface wrinkled TPU film with wrinkle wave length of 2.4 μm demonstrated an excellent enhancement in output voltage (130%), current (180%), and maximum transfer charge (130%) when paired with surface structured polydimethylsiloxane film in a TENG. Due to the excellent durability and flexibility of the composing materials, the developed TENG showed outstanding stability in long-term continuous operation. With a high power density of 0.5 W/m² achieved on a 10⁷ Ω external load, the flexible TENG could be used to charge capacitors, power light-emitting-diodes, and served as a self-powered sensor to detect various human movement behaviors. This work provides a new path for the fabrication of surface wrinkled films for the sustainable development of high performance TENGs.     

Perovskite-SrTiO3/TiO2/PDA as photoelectrochemical glucose biosensor

The complexity of the biological sample to be tested requires the sensor to have a wide monitoring range, accurate selectivity, and excellent environmental tolerance. Here, we report a new strategy of in situ transformation of perovskite to form a heterojunction and combined with bioactive enzyme protective substances, thereby achieving a collection of multiple sensing properties. Through in situ conversion of TiO₂ to SrTiO₃ to form a heterojunction to provide high oxidation activity and protection for GOx through PDA, the TiO₂/SrTiO₃/PDA/GOx biosensor achieves an ultra-wide linear detection range of 0–32 mM. Such a range can effectively monitor the physical condition of people with high blood sugar levels (above 20 mM). Good stability, anti-interference, environmental tolerance, and accurate human blood detection all prove the excellent sensing performance and practical application potential of the TiO₂/SrTiO₃/PDA/GOx biosensor.     

3D-Printed Flexible Piezoresistive Sensors for Stretching and Out-of-Plane Forces

Conductive polymer composites (CPCs) of carbon nanotubes (CNTs) and graphite nanosheet (GNP)-filled thermoplastic polyurethane (TPU) are 3D-printed into flexible piezoresistive sensors via fused filament fabrication. The sensor, with a customized lever-cross structure, allows detection of stretching and out-of-plane forces of different magnitudes and frequencies. The out-of-plane force direction is obtained by combing the relative electrical resistance change in the cross section of the sensor with a force analysis. The 75-CNT/25-GNP sensor (CNT-to-GNP mass ratio of 75%-to-25%) demonstrates excellent sensing performance at a total nanoparticle loading of 3 wt%. The linearity of the 75-CNT/25-GNP sensor is 0.98, while those of the 100-CNT and 50-CNT/50-GNP sensors are 0.93 and 0.86, respectively. The gauge factor of the 75-CNT/25-GNP sensor is 52% higher than that of the 100-CNT sensor, and its sensing strain range is 79% above that of the 50-CNT/50-GNP sensor. Excellent sensing stability is demonstrated for the 75-CNT/25-GNP sensor after 1500 stretching (out-of-plane force) cycles. The synergistic effect of CNTs and GNPs on sensing performance of piezoresistive sensors is clearly shown in this study.     

Cu/Cu2O nanoparticles modified Ti3C2 MXene with in-situ formed TiO2-X for detection of hydrogen peroxide

Hydrogen peroxide (H₂O₂) is frequently used in various chemical reactions, the food industry, environmental protection, and the medical and biological fields. Cost-effective, simple, and quick detection technologies with great sensitivity are highly desired. The emerging two-dimensional MXene is favorable in the sensing field due to its outstanding conductivity, stability, and large surface area. Moreover, the in-situ generated TiO_2-X on Ti₃C₂ MXene has been proven an excellent biosensor material due to its biocompatibility. Herein, we decorated Cu/Cu₂O nanoparticles onto Ti₃C₂ MXene with in-situ generated TiO_2-X nanoparticles, forming heterojunction through a simple one-step hydrothermal process. The Cu/Cu₂O/TiO_2-X/Ti₃C₂ (Cu/Cu₂O/TT) exhibits good electrochemical sensing capability toward H₂O₂, with a linear range up to 28.328 mM, a sensitivity of 312 μA mM^?1 cm^?2, and a detection limit (LOD) of 0.42 μΜ. The synergistic interactions between Cu/Cu₂O nanoparticles and TiO_2-X/Ti₃C₂ heterojunction not only improved electron transfer and electrocatalytic activity, but also facilitated the mobility of targeting molecules on the catalyst due to the abundance of exposed catalytic sites. Therefore, compared to TiO_2-X/Ti₃C₂, Cu/Cu₂O/TT has a lower LOD, faster reaction, and five times the sensitivity. Additionally, the outstanding photoelectrochemical (PEC) sensing performance is demonstrated of Cu/Cu₂O/TT for H₂O₂ detection, displaying a low LOD, long-term stability, repeatability, and selectivity. This report may expand the application of MXene-based materials as electrochemical sensors.     

Layered Ti-based oxide hierarchical nanocomposites derived from flash oxidation of MXene with enhanced photocatalytic and microwave transparent performance

Ti-based oxide hierarchical nanocomposites assembled into a two-dimensional structure were synthesized via a facile, flash oxidation of MXene (Ti₃C₂T_x) at 200–900 °C for 1 or 3 min. The oxidation temperature primarily controlled the phase composition. Particularly, TiOF₂ nanoparticles decorated MXene sheets formed at low oxidation temperatures (200 and 400 °C) and exhibited preferable activity in methylene blue (MB) photodegradation, reaching a ～90 % and ～56 % removal under ultraviolet and visible light illumination for 3 h, respectively. Due to the excellent electronic conductivity of MXene, the decreasing bandgap energy extended absorption in the visible range of the solar spectrum, suggesting a promising candidate for wide-range responsive photocatalytic applications. In contrast, TiO₂ nanoparticles assembled into 2D morphology formed at high temperatures (500–900 °C), possessing good microwave transparent performance because of low imaginary permittivity and dielectric loss tangent.     

High performance H2 sensor based on rGO-wrapped SnO2–Pd porous hollow spheres

Hydrogen (H₂) sensors based on metal oxide semiconductors (MOS) are promising for many applications such as a rocket propellant, industrial gas and the safety of storage. However, poor selectivity at low analyte concentrations, and independent response on high humidity limit the practical applications. Herein, we designed rGO-wrapped SnO₂–Pd porous hollow spheres composite (SnO₂–Pd@rGO) for high performance H₂ sensor. The porous hollow structure was from the carbon sphere template. The rGO wrapping was via self-assembly of GO on SnO₂-based spheres with subsequent thermal reduction in H₂ ambient. This sensor exhibited excellently selective H₂ sensing performances at 390 °C, linear response over a broad concentration range (0.1–1000 ppm) with recovery time of only 3 s, a high response of ～8 to 0.1 ppm H₂ in a minute, and acceptable stability under high humidity conditions (e. g. 80%). The calculated detection limit of 16.5 ppb opened up the possibility of trace H₂ monitoring. Furthermore, this sensor demonstrated certain response to H₂ at the minimum concentration of 50 ppm at 130 °C. These performances mainly benefited from the special hollow porous structure with abundant heterojunctions, the catalysis of the doped-PdO_x, the relative hydrophobic surface from rGO, and the deoxygenation after H₂ reduction.     

Highly Stretchable,Transparent, and Bio‐Friendly Strain Sensor Based on Self‐Recovery Ionic‐Covalent Hydrogels for Human Motion Monitoring

Stretchable, flexible, and strain‐sensitive hydrogels have gained tremendous attention due to their potential application in health monitoring devices and artificial intelligence. Nevertheless, it is still a huge challenge to develop an integrated strain sensor with excellent mechanical properties, broad sensing range, high transparency, biocompatibility, and self‐recovery. Herein, a simple paradigm of stretchable strain sensor based on multifunctional hydrogels is prepared by constructing synergistic effects among polyacrylamide (PAM), biocompatible macromolecule sodium alginate (SA), and Ca ion in covalently and ionically crosslinked networks. Under large deformation, the dynamic SA‐Ca²⁺ bonds effectively dissipate energy, serving as sacrificial bonds, while the PAM chains bridge the crack and stabilize the network, endowing hydrogels with outstanding mechanical performances, for instance, high stretchability and compressibility, as well as excellent self‐recovery performance. The hydrogel is assembled to be a transparent and wearable strain sensor, which has good sensitivity and very wide sensing range (0–1700%), and can precisely detect dynamic strains, including both low and high strains (20–800% strain). It also exhibits fast response time (800 ms) and long‐time stability (200 cycles). The sensor can monitor and distinguish complicated human motions, opening up a new route for broad potential applications of eco‐friendly flexible strain‐sensing devices.