Finger Bending Research Articles

Ultrasensitive iontronic pressure sensor based on microstructure ionogel dielectric layer for wearable electronics

Flexible pressure sensors show great promise for applications in such fields as electronic skin, healthcare, and intelligent robotics. Traditional capacitive pressure sensors, however, face the problem of low sensitivity, which limits their wider application. In this paper, a flexible capacitive pressure sensor with microstructured ionization layer is fabricated by a sandwich-type process, with a low-cost and simple process of inverted molding with sandpapers being used to form a thermoplastic polyurethane elastomer ionic film with double-sided microstructure as the dielectric layer of the sensor, with silver nanowires as electrodes. The operating mechanism of this iontronic pressure sensor is analyzed using a graphical method, and the sensor is tested on a pressure platform. The test results show that the sensor has ultrahigh pressure sensitivities of 3.744 and 1.689 kPa−1 at low (0–20 kPa) and high (20–800 kPa) pressures, respectively, as well as a rapid response time (100 ms), and it exhibits good stability and repeatability. The sensor can be used for sensitive monitoring of activities such as finger bending, and for facial expression (smile, frown) recognition, as well as speech recognition.

Hierarchical elastic and conductive multiwall carbon nanotube carboxymethylcellulose silica hybrid aerogel for strain sensors

Abstract Flexible and wearable piezoelectric pressure sensors have attracted extensive interest for their potential applications in human health monitoring. However, it remains a challenge to fabricate exceedingly elastic, conductive and steady strain-sensitive aerogels. Herein, an elastic and conductive carboxymethylcellulose sodium/methyltrimethoxysilane/multiwall carbon nanotube (CMC/MTMS/MWCNT) aerogel with interconnected porous microstructure was fabricated by a solution mixing and freeze-drying technique. Owing to covalent, ionic and hydrogen-bonding interactions between flexible CMC chains, MTMS and MWCNTs, the as-prepared CMC/MTMS/MWCNT hydrophobic aerogel with 50 wt% MWCNT loading exhibits good elasticity (1500 steady compression cycles at 30% strain), a broad pressure detection range (0–150 kPa) and reasonable compression sensitivity with gauge factor of 1.02 under 20%–30% strain. Additionally, the CMC/MTMS/MWCNT aerogel was used as a strain sensor and successfully demonstrated human motion detection—not only large-scale actions (finger bending) but also small-scale muscle movements (swallowing). With these results, our CMC/MTMS-50 aerogel is a promising candidate for utilization in flexible and wearable strain sensors.

Research on the Application of Flexible Pressure Sensors in Wearable Devices

The potential applications of transparent, adaptable electronic devices in the human body are driving up demand for them. For flexible and wearable electronics, such as medical surveillance devices and artificial skin, pressure sensing is mandatory. The flexibility and sensitivity of pressure sensors have advanced recently owing to developments in material and device structure. Moreover, their low manufacturing costs enable widespread implementation, leading to promising application prospects. The sensors utilize different materials and structures, including capacitive pressure sensors with ionically charged CFMs, magnetic particle-infused carbon sponges, CNT-PDMS composites, and MoSe2/MWNT combinations. These sensors offer advantages such as high sensitivity, wide pressure-detecting ranges, optical transparency, and energy efficiency. They can detect both large and subtle human movements, from walking and finger bending to breathing and eye blinking. The fabrication methods range from simple and cost-effective processes to more complex techniques like photolithography. Many of the sensors incorporate carbon nanotubes (CNTs) in various forms, exploiting their excellent electrical properties. The review highlights the potential of these sensors for healthcare monitoring, clinical diagnosis, and integration into wearable electronics, emphasizing their flexibility, biocompatibility, and ability to provide real-time, non-invasive measurements of physiological signals. Moreover, their low manufacturing costs enable widespread implementation, leading to promising application prospects.

Study on Highly Sensitive Capacitive Pressure Sensor Based on Silk Fibroin-Lignin Nanoparticles Hydrogel.

Silk fibroin (SF) hydrogel has been proven to have excellent applications in the field of pressure sensors, but its sensing performance still needs improvement. A flexible hydrogel prepared from natural macromolecular materials was developed, and lignin nanoparticles (LNPs) were introduced during the preparation of the SF hydrogel. When LNPs account for 3% of SF, the sensing unit of the SF-LNPs3% hydrogel exhibits high stress sensitivity (1.32 kPa-1), fast response speed (<0.1 s), and superior cycle stability (≥8000 cycles). The sensor can detect human motion information, such as finger bending, elbow bending, and pulse signals. When worn at the vocal cord position, it can detect the peak value of the characteristic signal during the wearer speaks. This work demonstrates that the SF-LNPs3% hydrogel has high sensitivity and shows great potential in the field of pressure sensors.

Triboelectric Bending Sensors for AI-Enabled Sign Language Recognition.

Human-machine interfacesand wearable electronics, as fundamentals to achieve human-machine interactions, are becoming increasingly essential in the era of the Internet of Things. However, contemporary wearable sensors based on resistive and capacitive mechanisms demand an external power, impeding them from extensive and diverse deployment. Herein, a smart wearable system is developed encompassing five arch-structured self-powered triboelectric sensors, a five-channel data acquisition unit to collect finger bending signals, and an artificial intelligence (AI) methodology, specifically a long short-term memory (LSTM) network, to recognize signal patterns. A slider-crank mechanism that precisely controls the bending angle is designed to quantitively assess the sensor's performance. Thirty signal patterns of sign language of each letter are collected and analyzed after the environment noise and cross-talks among different channels are reduced and removed, respectively, by leveraging low pass filters. Two LSTM models are trained using different training sets, and four indexes are introduced to evaluate their performance, achieving a recognition accuracy of 96.15%. This work demonstrates a novel integration of triboelectric sensors with AI for sign language recognition, paving a new application avenue of triboelectric sensors in wearable electronics.

Flexible and Stable GaN Piezoelectric Sensor for Motion Monitoring and Fall Warning.

Wearable devices have potential applications in health monitoring and personalized healthcare due to their portability, conformability, and excellent mechanical flexibility. However, their performance is often limited by instability in acidic or basic environments. In this study, a flexible sensor with excellent stability based on a GaN nanoplate was developed through a simple and controllable fabrication process, where the linearity and stability remained at almost 99% of the original performance for 40 days in an air atmosphere. Moreover, perfect stability was also demonstrated in acid-base environments, with pH values ranging from 1 to 13. Based on its excellent stability and piezotronic performance, a flexible device for motion monitoring was developed, capable of detecting motions such as finger, knee, and wrist bending, as well as swallowing. Furthermore, gesture recognition and intelligent fall monitoring were explored based on the bending properties. In addition, an intelligent fall warning system was proposed for the personalized healthcare application of elders by applying machine learning to analyze data collected from typical activities. Our research provides a path for stable and flexible electronics and personalized healthcare applications.

TacFR-Gripper: A Reconfigurable Fin-Ray-Based Gripper with Tactile Skin for In-Hand Manipulation

This paper introduces the TacFR-Gripper, a novel reconfigurable soft robotic gripper inspired by the Fin-Ray effect and equipped with tactile skin. The gripper incorporates a four-bar mechanism for accurate finger bending and a reconfigurable design to change the relative positions between the fingers and palm, enabling precise and adaptable object grasping. This 5-Degree-of-Freedom (DOF) soft gripper can facilitate dexterous manipulation of objects with diverse shapes and stiffness and is beneficial to the safe and efficient grasping of delicate objects. An array of Force Sensitive Resistor (FSR) sensors is embedded within each robotic fingertip to serve as the tactile skin, enabling the robot to perceive contact information during manipulation. Moreover, we implemented a threshold-based tactile perception approach to enable reliable grasping without accidental slip or excessive force. To verify the effectiveness of the TacFR-Gripper, we provide detailed workspace analysis to evaluate its grasping performance and conducted three experiments, including (i) assessing the grasp success rate across various everyday objects through different finger configurations, (ii) verifying the effectiveness of tactile skin with different control strategies in grasping, and (iii) evaluating the in-hand manipulation capabilities through object pose control. The experimental results indicate that the TacFR-Gripper can grasp a wide range of complex-shaped objects with a high success rate and deliver dexterous in-hand manipulation. Additionally, the integration of tactile skin is demonstrated to enhance grasp stability by incorporating tactile feedback during manipulations.

Piezoelectric Energy Harvesting and Body Motion Sensing of a Pair of 0D Chiral Hybrid Metal Halides.

Chiral hybrid metal halides have received considerable attention in circularly polarized luminescence and spintronics due to their structural diversity, ease of synthesis, and chemical versatility. However, only a limited number of chiral metal halides have been utilized in piezoelectric energy harvesters and motion sensors. Furthermore, the exploration of 0D chiral piezoelectric materials is still in their early stage, offering substantial potential for further development. Herein, a pair of enantiomorphic hybrid metal halide piezoelectrics, R-(1-2-NEA)2CdCl4 and S-(1-2-NEA)2CdCl4 (1-2-NEA+ = 1-(2-naphthyl) ethylamine cation), were synthesized and structurally characterized. In addition, the devices comprising R-(1-2-NEA)2CdCl4/PDMS or S-(1-2-NEA)2CdCl4/PDMS (PDMS = polydimethylsiloxane) composite films were fabricated, and the energy harvesting performance of the devices with varying halide contents was explored. The results demonstrate that the devices comprising 10 wt% R-(1-2-NEA)2CdCl4/PDMS or S-(1-2-NEA)2CdCl4/PDMS exhibit significant energy harvesting capabilities, with an open-circuit voltage and a short-circuit current up to 8.24 V and 0.72 μA, respectively. Furthermore, the devices display exceptional mechanical durability after 4500 cycles and demonstrate excellent sensitivity in detecting various human body movements, such as walking, elbow bending, and finger bending. This study highlights the considerable potential of chiral hybrid metal halides for use in energy harvesting and wearable sensors.

Development of a Nano-toughened multifunctional composite hydrogel based on chitosan and its applications in catalytic and flexible sensors.

In this study, we developed a novel composite catalytic hydrogel, which integrates excellent mechanical properties, catalytic activity, and sensing performance. Discarded hydrogel sensors are reused as templates for in-situ generation of metal nanoparticles, and multifunctional hydrogels combining sensing and catalysis are realized. Polyacrylamide (PAM) provides a three-dimensional network structure, while octadecyl methacrylate (SMA) acts as a hydrophobic association center, enhancing the structural stability of the hydrogel. Dopamine coated with silica (PDA@SiO₂) nanoparticles act as nanoreinforcement points, further improving the mechanical strength of the hydrogel. Graphene(GN) imparts the hydrogel with good electrical conductivity and sensing capabilities. The hydrogel exhibits a strain of 1878 %, a tensile strength of 668 kPa, and toughness of 5615.2 kJ/m3, while also demonstrating excellent sensing performance, with gauge factor (GF) of 7.49 and response time of 168 ms, enabling a quick response to external strain. It effectively detects human motions, such as finger bending and joint movement. Additionally, PDA@SiO₂ acts as an active site for the synthesis of Ag NPs, facilitating the reduction of Rhodamine B at 25 °C with a catalytic rate constant of 0.504 min-1. After five catalytic cycles, the hydrogel retains over 99 % efficiency, demonstrating excellent cyclic stability and recyclability.

Flame-induced performance enhancement of MXene-based nanocomposite sponge for infrared stealth and strain sensing

Assembling MXene nanofillers on a macroscopic carrier via the non-covalent bonding forces is one of the most efficient paths for preparing the MXene-based nanocomposites with multi functions and hierarchical structure. However, the frequently-used substrates, such as cotton fabric, synthetic textile, and polymer sponge are highly flammable, severely restricting the practical applications in some highly integrated scenarios. Herein, we report a facile design strategy that enables us to readily achieve the flame retardant MXene-based nanocomposites for highly efficient infrared stealth and strain sensing even when used in high-temperature environments. In particular, a phosphorus-nitrogen rich compound (HPTCP) was intercalated into the laminates of Ti3C2Tx-MXene to construct a hybrid flame retardant that was coated on the skeletons of melamine sponge by repeated dip-coating procedures. As a result of the synergistic effect among multicomponent, the Ti3C2Tx-HPTCP coated sponge displays excellent structural stability in real fire. In this case, flame treatment was adopted to create micro-/nano-scale cracks in the coated sponge and skeletons, significantly enhancing the sensitivity (∼0.20 kPa−1) and shortening the response time (69 ms) to strain. The burned sponge sensor can be employed for monitoring various human motions, from tiny throat vibrations and facial expressions to large-scale finger and knee bending. Besides, the burned sample still maintains the superior infrared stealth performance with a wide stealth temperature range, a large reduction in radiation temperature of 154 °C for the object temperature of 300 °C, and long-term working stability at high temperatures. Given the simple fabrication process, multilevel structural design, and stable performance, this work provides a promising strategy for addressing the flammability issue of template-based composite materials

Post-Transition Metal Dichalcogenide SnS2 Nanoflower/PVDF Composite: A Smart Wearable Self-Powered Mechanosensor.

The escalating demand for wearables has led to a surge in the development of portable and flexible electronics. Consequently, exploring different materials for the efficient design of the device has become an inevitable aspect of this particular research area. Therefore, in this work, we present post-transition metal dichalcogenide tin disulfide (SnS2) nanoflowers, to effectively engineer the polyvinylidene fluoride (PVDF) functional layer, which serves as the heart of the device. These hydrothermally grown SnS2 nanoflowers can significantly nurture the physiochemical properties of the PVDF matrix. Consequently, the assembled optimized device is capable of generating an output voltage of 60 ± 4 V, with an output current of 8 ± 0.4 μA, while maintaining a good output power density of 87.11 μW·cm-2. The device successfully harvested mechanical energies from several biomechanical movements including finger, elbow, neck, and wrist bending. Furthermore, the optimized device demonstrated a high efficiency in static and dynamic pressure sensing. This utilization of post-transition metal dichalcogenides paves the way for groundbreaking improvements in the fields of biomechanical energy harvesting and static and dynamic pressure sensing.

Self-healing and transparent ionic conductive PVA/pullulan/borax hydrogels with multi-sensing capabilities for wearable sensors

Conductive hydrogels as wearable sensors have been used for numerous applications in human motion detection, personal healthcare monitoring and other diverse scenarios. However, it remains a challenge to integrate self-healing ability, multiple sensing capabilities, and transparency in one single unit. In this work, multifunctional polyvinyl alcohol (PVA)/Pullulan/Borax conductive hydrogels were fabricated by introducing borate ester bonds and hydrogen bonds. The described hydrogels showed fast self-healing properties, which could autonomously completely recover within 15 s. The hydrogels possessed high optical transparency (92.9%) in the visible light range and had multi-sensing capabilities, such as strain, temperature and humidity sensing. The assembled hydrogel sensor displayed a high strain sensitivity of 2.74 within the strain range of 300%, and it could be used to monitor human motions such as finger and wrist bending. In addition, the hydrogel sensor could sense temperature variations with a temperature coefficient of resistance of −0.914 °C−1 over 28–46 °C. Besides, the hydrogel sensor demonstrated the humidity sensing ability and can recognize human inhale and exhale. The overall sensing performance of the PVA/Pullulan/Borax hydrogel was satisfactory and repeatable. This conductive hydrogel shows great potential in wearable electronics and personal healthcare and inspires a new generation of multifunctional hydrogel sensors.

Bio-inspired carbon-based artificial muscle with precise and continuous morphing capabilities

Abstract In the face of advancements in micro-robotics, intelligent control, and precision medicine, artificial muscle actuation systems must meet demands for precise control, high stability, environmental adaptability, and high integration miniaturization. Carbon materials, with their lightweight, high strength, conductivity, and flexibility, show great potential for artificial muscles. Inspired by the butterfly's proboscis, we have developed a carbon-based artificial muscle, HsGDY-M, fabricated efficiently using an emerging hydrogen-substituted graphdiyne (HsGDY) film with an asymmetrical surface structure. This muscle features reversible, rapid, and continuously adjustable deformation capabilities similar to the butterfly's proboscis, triggered by the conversion of carbon bonds. The size of the HsGDY-M can be tuned by tailoring the HsGDY film width from ∼1 cm to 100 µm. Our research demonstrates HsGDY-M's stability and adaptability, maintaining performance at temperatures as low as -25°C. This artificial muscle was successfully integrated into a robotic mechanical arm, allowing it to swiftly adjust its posture and lift objects up to 11 times its own weight. Its beneficial responsiveness is transferable, enabling the transformation of “inert” objects like copper foil into actuators via surface bonding. Since its super sensitive and rapid deformation, HsGDY-M was applied to create a real-time tracking system for human finger bending movements, achieving real-time simulation and large-hand-to-small-hand control. Our study indicates that HsGDY-M holds significant promise for advancing smart robotics and precision medicine.

Solution‐Processable MOF‐on‐MOF System Constructed via Template‐Assisted Growth for Ultratrace H2S Detection

AbstractConductive metal–organic frameworks (c‐MOFs) hold promise for highly sensitive sensing systems due to their conductivity and porosity. However, the fabrication of c‐MOF thin films with controllable morphology, thickness, and preferential orientation remains a formidable yet ubiquitous challenge. Herein, we propose an innovative template‐assisted strategy for constructing MOF‐on‐MOF (Ni3(HITP)2/NUS‐8 (HITP: 2,3,6,7,10,11‐hexamino‐tri (p‐phenylene))) systems with good electrical conductivity, porosity, and solution processability. Leveraging the 2D nature and solution processability of NUS‐8, we achieve the controllable self‐assembly of Ni3(HITP)2 on NUS‐8 nanosheets, producing solution‐processable Ni3(HITP)2/NUS‐8 nanosheets with a film conductivity of 1.55×10−3 S ⋅ cm−1 at room temperature. Notably, the excellent solution processability facilitates the fabrication of large‐area thin films and printing of intricate patterns with good uniformity, and the Ni3(HITP)2/NUS‐8‐based system can monitor finger bending. Gas sensors based on Ni3(HITP)2/NUS‐8 exhibit high sensitivity (LOD~6 ppb) and selectivity towards ultratrace H2S at room temperature, attributed to the coupling between Ni3(HITP)2 and NUS‐8 and the redox reaction with H2S. This approach not only unlocks the potential of stacking different MOF layers in a sequence to generate functionalities that cannot be achieved by a single MOF, but also provides novel avenues for the scalable integration of MOFs in miniaturized devices with salient sensing performance.

Solution-Processable MOF-on-MOF System Constructed via Template-Assisted Growth for Ultratrace H2S Detection.

Conductive metal-organic frameworks (c-MOFs) hold promise for highly sensitive sensing systems due to their conductivity and porosity. However, the fabrication of c-MOF thin films with controllable morphology, thickness, and preferential orientation remains a formidable yet ubiquitous challenge. Herein, we propose an innovative template-assisted strategy for constructing MOF-on-MOF (Ni3(HITP)2/NUS-8 (HITP: 2,3,6,7,10,11-hexamino-tri (p-phenylene))) systems with good electrical conductivity, porosity, and solution processability. Leveraging the 2D nature and solution processability of NUS-8, we achieve the controllable self-assembly of Ni3(HITP)2 on NUS-8 nanosheets, producing solution-processable Ni3(HITP)2/NUS-8 nanosheets with a film conductivity of 1.55×10-3 S ⋅ cm-1 at room temperature. Notably, the excellent solution processability facilitates the fabrication of large-area thin films and printing of intricate patterns with good uniformity, and the Ni3(HITP)2/NUS-8-based system can monitor finger bending. Gas sensors based on Ni3(HITP)2/NUS-8 exhibit high sensitivity (LOD~6 ppb) and selectivity towards ultratrace H2S at room temperature, attributed to the coupling between Ni3(HITP)2 and NUS-8 and the redox reaction with H2S. This approach not only unlocks the potential of stacking different MOF layers in a sequence to generate functionalities that cannot be achieved by a single MOF, but also provides novel avenues for the scalable integration of MOFs in miniaturized devices with salient sensing performance.

High-Performance Flexible Pressure Sensor with Micropyramid Structure for Human Motion Signal Detection and Electromagnetic Interference Shielding.

Flexible pressure sensors have a wide range of applications in the field of human motion signal detection, but the electromagnetic radiation generated during the monitoring process has become an unavoidable problem. Nowadays, it is still a challenge to develop high-performance pressure sensors with excellent electromagnetic interference (EMI) shielding performance. Herein, the Ti3C2TX MXene/carbon fiber/multiwalled carbon nanotube/polydimethylsiloxane (MXene/CMP) films with a micropyramidal structure were developed by the technology of vacuum high-temperature hot pressing and spray deposition. Benefiting from the dielectric loss of the conductive fillers and the presence of the microstructure, the MXene/CMP film exhibits excellent EMI shielding performance, and the EMI shielding efficiency (SE) can reach 49.37 dB. Besides, the introduction of CF effectively improves the mechanical properties of the MXene/CMP films, and the MXene nanosheets deposited on the surface of the film can reduce stress concentration, which in turn delays the expansion of cracks. Furthermore, the MXene/CMP sensor exhibits high sensitivity (89.76 kPa-1) and fast response/recovery time (61/60 ms). The deformation of microstructure and the construction of conductive networks enable the sensor to realize the monitoring of human motion signals (such as finger bending, knee bending, wrist bending, etc.). Meanwhile, the sensor maintains sensing stability even after 2000 pressure cycles, which can be attributed to the improvement in mechanical properties. In summary, the developed high-performance flexible pressure sensor with micropyramid structure has great application prospects in wearable devices and healthcare.

Next-gen strain sensors: Self-healing, ultra-sensitive, lightweight, and durable MWCNT-silicone rubber for advanced human motion tracking

Strain sensors that have flexible wearable forms can be applied in different aspects, such as in soft robotics, human-computer interaction, motion monitoring, and medical treatment process. The main challenge is creating lightweight, flexible sensors with high sensitivity. In this study, we developed flexible strain sensors using a simple sandwich manufacturing method. To achieve this, multi-walled carbon nanotubes (MWCNTs) were chosen for their excellent conductivity, while silicone rubber (SR) provided a flexible and durable substrate. Advanced SEM-EDX and FTIR analyses were conducted to assess the material structure. Furthermore, the electromechanical performance of the sensors was thoroughly evaluated, highlighting their potential in real-world applications. Electromechanical performance evaluation showed that the SR/0.7-MWCNT/SR sensor in the 0–90 % strain range had a sensitivity of 34.47, an increase of 53.35 %, and a linearity of 0.978, an increase of 10 % compared to the SR/0.5-MWCNT/SR sensor. In addition, the sensor has extremely fast response and recovery times of 65 ms and 60 ms, respectively. The sensor is also able to withstand up to 1.200 cycles of stretching, twisting, and bending. The sensor also exhibited good autonomous electromechanical self-healing properties against physical damage. The sensor developed in the present study are proven to be used to detect human movements such as finger bending, wrist, elbow, and knee movements.

Leveraging wearable sensors and machine learning for posture-based detection of carpal tunnel syndrome

Abstract Carpal tunnel is associated with long-term use of the wrist and hand for various activities such as typing, welding, or poor working postures. Carpal Tunnel Syndrome (CTS) may cause severe pain and discomfort in the hand and wrist, and in some circumstances, surgery becomes inevitable. The objective of this study is to prevent typing postures, which can be ascertained as predisposing subjects to CTS development. The data used in this study is an array of wrist wearable sensors to capture flexion, extension, and bending of fingers while using a keyboard or mouse. Machine learning is employed on the data in order to identify risk factors indicative of a high probability of CTS. The analyzed models are linear regression, Support Vector Machine, Random Forest, Multilayer Perceptron, Convolution Neural Network, and Long Short Term Memory. The conditions for assessing the performance of the data models include RMS error, coefficients of determination, and mean absolute percentage error. In this research, I conducted an exploratory data analysis (EDA) to gain an initial understanding of the dataset. Following the exploratory phase, I applied feature extraction techniques, specifically Principal Component Analysis (PCA). As put forward for the proposed research, the strategies to prevent risky occupations have broad potential at the present time, especially in the case of CTS when preventing repetitive wrist movements.

Dual‐active‐layer flexible piezoresistive sensor based on wrinkled microstructures and electrospun fiber network for human‐related motion sensing applications

AbstractFlexible pressure sensors with high sensitivity and a wide detection range must be developed for practical applications. In this study, a dual‐active‐layer flexible piezoresistive sensor was developed. A reduced graphene oxide film with wrinkled microstructures was prepared by a simple and low‐cost substrate pre‐stretching method and used as the first active layer. A thermoplastic polyurethane electrospun fiber membrane was modified by fast polydopamine coating and ultrasonication with multi‐walled carbon nanotubes and used as the second active layer. Owing to the continuously changing conductive pathways created by the wrinkled microstructures and fiber network under pressure deformation, the sensor achieved a detection range of 0–100 kPa, with sensitivities of 8.5, 1.35, and 0.39 kPa−1 in the ranges of 0–1, 1–20, and 20–100 kPa, respectively. Additionally, the sensor exhibited a low detection limit (2 Pa), response and recovery times of 105 and 85 ms, respectively, and reliable service performance over 10,000 loading/unloading cycles. The sensor enabled real‐time monitoring of finger and wrist bending, beaker‐holding, and fingertip‐sliding on a touch screen, demonstrating its feasible applications in wearable electronics and human–machine interface devices.

Preparation and application of organic hydrogels incorporating polyacrylamide/sodium alginate/DMSO for enhanced anti-drying, anti-freezing, and self-healing properties

The double-network hydrogel comprises two asymmetrically structured cross-linked networks, demonstrating exceptional mechanical properties and possessing significant potential for application in the field of flexible sensors. However, conventional hydrogels primarily disperse in water as a medium and continuously lose moisture in natural environments, rendering them incapable of retaining hydration over extended periods and unsuitable for utilization under low-temperature conditions. In this study, we devised an organic hydrogel based on polyacrylamide (PAM), sodium alginate (SA), and dimethyl sulfoxide (DMSO). Through hydrogen bonding interactions among DMSO molecules, polyacrylamide, and sodium alginate, this organic hydrogel not only exhibits anti-drying and anti-freezing properties but also demonstrates self-healing characteristics. Moreover, the organic hydrogel showcases remarkable mechanical properties and conductivity capabilities that render it suitable for constructing flexible strain sensors to monitor human movements such as finger bending, elbow flexion, knee joint bending, and ankle extension. Additionally, the sensor exhibits excellent stability and durability.