Assistive chopsticks using joint mechanisms have been developed for people with disabilities and beginners. This joint mechanism can assist in food-serving using chopsticks. However, a suitable joint position for assisting chopstick operations has not yet been investigated. Thus, the purpose of this study was to investigate the effects of assistive chopsticks with two joint positions (top and grip) on food-serving tasks to find suitable joint positions. The participants were 10 young males. Participants moved 10 boiled soybeans to adjacent dishes using normal chopsticks (“control”) and assistive chopsticks with two joint positions (“grip position” and “top position”). To evaluate fatigue during chopstick operation, the activity of the flexor digitorum superficialis muscles was measured using an EMG sensor. The comfort of chopstick operations was investigated using a visual analog scale (VAS). The performance of the chopstick operation was evaluated based on the total required time for each operation. The results of the EMG sensor showed that the muscle activities of assistive chopsticks were lower than those of the control condition (normal chopsticks). In addition, the VAS results showed that the top joint caught beans more easily than in the grip position. Furthermore, there was no difference in the required time for performance in all conditions. These results indicate that assistive chopsticks with a joint mechanism on the top position are the most suitable for food-serving tasks. Furthermore, it is considered that the top position is better than the grip position for the joint mechanism of the assistive chopsticks.

Excessive trunk flexion of caregivers during patient handling causes lower back pain. Thus, the trunk flexion angle of caregivers should be monitored and improved in daily patient handling tasks. A single inertial sensor is considered a suitable wearable sensor for monitoring trunk posture during patient handling because it is installed on popular devices such as smartphones. However, the accuracy of a single inertial sensor has not been evaluated for trunk flexion measurements in patient handling. The objective of this study was to evaluate the accuracy of a single inertial sensor for trunk flexion measurements during patient handling. In the experiment, ten participants performed patient repositioning. The trunk flexion angle during patient repositioning was measured using an optical motion capture system as the ground truth, and a single inertial sensor on the trunk. The Madgwick filter was applied to calculate the trunk flexion angle using the acceleration and gyro data obtained from an inertial sensor. The correlation and root mean square error (RMSE) values between the optical motion capture system and inertial sensor were calculated to evaluate accuracy. The results showed that the correlation values between the inertial sensor and the ground truth were greater than 0.9. These results indicate that a single inertial sensor can be used to monitor temporal changes in trunk flexion during patient handling. On the other hand, the results showed that RMSE values were more than 10 degrees. In future work, these errors should be improved by developing novel signal processing methods.

Manual lifting causes low back pain due to lumbar load from an unsuitable posture. In particular, a stooping posture without knee movement is considered an unsuitable posture with large lumbar loads. In contrast, a squatting posture using knee flexion and extension is recommended as a suitable posture with small lumbar loads. From this background, the lifting posture should be continuously monitored and improved to prevent low back pain. Occupational postures are monitored by human observation or specific devices, such as optical motion capture systems. However, human observation has limitations owing to the repeatability and fatigue of the observers. In addition, specific devices, such as optical motion capture systems, are expensive for use in various occupational fields. Therefore, we developed a posture recognition method for stooping and squatting postures during manual lifting using a common monocular camera and machine learning. The purpose of this study was to develop a prototype lifting posture monitoring system using a posture recognition method to prevent low back pain. In addition, to develop the monitoring system, the proposed posture recognition method was modified to extract lifting postures from a movie. A prototype of the lifting posture monitoring system was implemented using HTML and JavaScript. The developed prototype system can recognize and display stooping and squatting lifting postures with different lumbar loads from real-time movies using a monocular camera. A modified posture recognition method was implemented using the MobileNetV2 model trained via Teachable Machine. The modified posture recognition method could recognize stooping lifting, squatting lifting, and standing (not lifting) with greater than 0.85 accuracy. This accuracy was comparable to that of human observations. These results indicate that the prototype lifting posture monitoring system can extract and recognize suitable and unsuitable postures from a movie to prevent low back pain.

Physiological monitoring of the heart is essential to know what condition our heart is going through. In this regard, wearable pressure and optoelectronic devices have received significant interest towards flexible and wearable healthcare applications such as pulse rate, blood oxygen level, and blood pressure monitoring. Therefore, we have developed a flexible capacitive-based pressure sensor for hemodynamic monitoring through an oscillometric waveform. This pressure sensor shows the potential to replace the existing rigid pressure sensor used in automated blood pressure devices currently available in the market. Since oscillometric techniques are operated intermittently, the photoplethysmography technique has emerged for continuous signal monitoring. However, available devices currently utilize inorganic photodetectors, which have limitations, such as rigid and high-cost manufacturing. As an alternative, organic photodiodes (OPDs) can also compensate for traditional inorganic photodetectors and provide additional features such as flexibility, low-cost manufacturing, and large-area scalability. This work also presents the design, development, and characterization of flexible OPD and their application in physiological monitoring through a comfortable and non-invasive technique. The photoplethysmogram (PPG) is recorded from the index finger in the transmission as well as reflection mode using red (630 nm) and green (530 nm) light, respectively. The collected PPG signals are used to calculate the hemodynamic parameters. Ultimately, this work demonstrates a flexible pressure sensor and an organic photodetector for arterial pulse monitoring and hemodynamic monitoring.

This study investigates the preparation of Pd/h-BNNSs/rGO composites and their application in ethanol electro-oxidation sensors. It begins with an introduction to direct ethanol fuel cells (DEFCs), highlighting the requirements for anode materials. The advantages of palladium (Pd) and platinum (Pt) as catalytic metals, along with the significance of carbon materials in catalysis, are discussed. This research innovatively integrates h-BN nanosheets with graphene oxide to develop a distinctive two-dimensional nanocomposite material, successfully loading Pd onto it for enhanced ethanol oxidation.The experimental section outlines the material preparation process, which includes synthesizing graphene oxide (GO), preparing h-BNNSs/rGO, and fabricating Pd/h-BNNSs/rGO composites. The structure and morphology of these composites are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). These analyses confirm the successful construction of the h-BNNSs/rGO composite and uniform loading of Pd. Additionally, Fourier-transform Raman spectroscopy (FT-Raman) and Fourier-transform infrared spectroscopy (FT-IR) further validate the structural characteristics.In electrochemical testing, 15% Pd/h-BNNSs/rGO demonstrates superior performance in alkaline environments compared to commercial Pd/C catalysts, exhibiting enhanced ethanol oxidation activity, greater electrochemical stability, and improved CO tolerance. Results from cyclic voltammetry and chronoamperometry corroborate these findings, indicating promising applications for this composite in ethanol electro-oxidation sensors. This study provides valuable insights for future research on sensors within ethanol fuel cells while contributing to advancements in high-performance ethanol electro-oxidation sensor technology.

The application of electrochromic technology in the field of sensors is an emerging and promising direction. It utilizes the reversible color change of a material when a voltage is applied to convert an electrical or chemical signal, which is difficult to observe directly, into an optical signal (color change) that is directly visible. This study develops a reversible electrochromic sensor based on proton-mediated regulation in NdNiO₃ thin films, enabling naked-eye visualization of weak electric field signals. The NdNiO₃ electrochromic sensor leverages electric-field-controlled insertion/extraction of hydrogen ions (H⁺) within the NdNiO₃ lattice to trigger a Mott transition. Under a positive electric field, H⁺ from the solution injects into the lattice, forming hydrogenated neodymium nickelate (HNdNiO₃). This alters the electronic orbital occupancy of Ni³⁺ (double eg orbital occupation), transitioning the material from a metallic state (low resistance, high reflectivity) to an insulating state (high resistance, high absorption), accompanied by a significant decrease in visible-light transmittance (54.5% optical modulation). Applying a reverse electric field extracts H⁺, restoring the original metallic state and achieving reversible optical/electrical switching. This mechanism converts imperceptible electrical signals into intuitive optical readouts, combining high sensitivity, rapid response kinetics, nanoscale spatial manipulation capability, as well as excellent cyclic stability (94.9% of the initial optical modulation is still retained after 1150 cycles). As such, it provides a groundbreaking tool for applications spanning marine exploration, biomedicine, and smart windows.

Photonic crystals are man-made submicron crystal structures consisting of two or more dielectric materials spatially arranged in a periodic manner.Photonic crystals have a unique photonic band gap (PBG) property. The position of the photonic bandgap can be modulated by change the lattice spacing or refractive index in order to control the propagation of light. Hydrogel is a 3D polymer matrix with large amount of water that can undergo a volume phase transition when stimulated by the external environment. By combining the optical characteristics of photonic crystals with the stimulatory response of hydrogels enables the conversion of chemical signals to optical signals and the detection of ions. In this work, polystyrene (PS) nano-spheres were uitlized to prepare photonic crystal templates with bright structural color by vertical deposition, and the mixture of hydroxyethyl methacrylate (HEMA) and vinyl imidazole (VIM) was injected into the photonic crystal templates and the hydrogel films were obtained by photo-polymerization under UV 365 nm exposure for 30 min. The obtained photonic crystal hydrogel films were sensitive to copper ion in buffer solution, the diffraction wavelengths blue-shifted with the copper ion concentration increased. The response time of photonic crystal hydrogel was 3 min, and the sensor film can be used for several times without property loss.

This study reports the development of two innovative paper-based thermal devices—temperature sensors and microheaters—fabricated using two custom-formulated, water-based conductive inks. The first ink consisted of reduced graphene oxide (rGO), while the second comprised a composite of carbon black (CB) and reduced graphene oxide (CB/rGO). Both inks were deposited onto glossy paper substrates via the rod coating technique, with variations in the number of coating passes (single and double) implemented to investigate the influence of film thickness on device performance. Electrical characterization revealed stable, ohmic behavior across all samples, with double-pass coatings exhibiting significantly lower sheet resistance, indicative of improved electrical conductivity. The temperature-sensing capabilities were evaluated through determination of the temperature coefficient of resistance (TCR), yielding values of –7.37×10^-3 °C^-1 for rGO-based sensors and –3.94×10^-3 °C^-1 for CB/rGO composites, both of which are consistent with theoretical predictions. The CB/rGO ink demonstrated enhanced performance as a printed microheater, exhibiting improved power efficiency and superior thermal uniformity. This enhancement is attributed to the incorporation of larger carbon black particles, which contribute to more effective thermal management and uniform heat distribution. These results underscore the potential of hybrid carbon-based inks for the fabrication of cost-effective, disposable, and environmentally sustainable thermal devices. The utilization of cellulose-based paper substrates in conjunction with graphene-derived functional materials presents a scalable, eco-friendly platform for the development of flexible, printed thermal electronics. The fabrication approach is compatible with large-area, low-cost production methods, thereby advancing the field of printed electronics with respect to performance, environmental compatibility, and manufacturability.

The visualization sensor based on the hydrogel photonic crystal (PC) is hot spot of the electronic skin research. The PC with structural colors can be stabilized by the hydrogel network and then the change of the network structure affects the arrangement of the crystal lattice of PC. In this research, polyvinyl alcohol (PVA) and sodium alginate (SA) with excellent biocompatibility were blended to prepare PVA/SA hydrogel, and their mechanical and mechanical properties were characterized. When the mass ratio of PVA to SA is 2:1, the maximum breaking elongation of the hydrogel can reach 163%, and the maximum tensile strength can reach 0.18 MPa. Further, the optimized PVA/SA hydrogel was combined with PC that self-assembled from monodisperse polystyrene colloids. The as prepaerd PVA/SA-PC showd bright structure colors. Then, Ca²⁺with good mixing mass ratio and conductivity were selected to test the mechanical and electrical properties of PVA/SA-PC films. Finally, a visual sensor was prepared that can detect Ca²⁺ ions as the hydrogel provides a carrier for the photonic crystals. The response results to Ca²⁺indicate that PVA/SA-PC film has good signal detection ability. Through observing the color change of the film, the purpose of real-time monitoring and real-time feedback can be achieved. Therefore, this film has great potential for development in the field of visual sensing.

2D molybdenum disulfide has great potential for use in advanced electronic and optoelectronic devices because of its unique properties. Due to the layered structure of MoS2, it is possible to control the electronic properties by varying the number of layers. This material has shown advantages in gas sensors such as a low detection limit. However, the stability of its characteristics needs improvement. One common method for creating 2D structures is mechanical exfoliation, which has low reproducibility. A different method used in this study is hydrothermal synthesis.

Sodium molybdate dihydrate, oxalic acid dihydrate and thiourea were used as precursors. The precursors were dissolved in distilled water and placed in an autoclave for 14 hours at 200°C. Chemical exfoliation of the produced particles was performed using zinc nitrate hexahydrate and hydrochloric acid. The nanoparticles were analyzed using scanning electron microscopy and X-ray photoelectron spectroscopy. The resulting powders were deposited onto sensor platform by spin-coating.

The gas-sensitive properties were studied using impedance spectroscopy. Sensitivity to isopropyl alcohol vapors was studied at room temperature, at different gas concentrations. The value of the sensor response was calculated using the formula for the real and imaginary components separately. It was found that, when 500 ppm of isopropyl alcohol vapor was applied, the maximum response in the real component was 2.6. With an increase in frequency above 4 kHz a decrease in sensitivity was observed. For the imaginary component, the maximum value was 5.3. A decrease in sensitivity is observed after 9kHz. The same parameters were measured at concentrations of 1000 ppm and 2000 ppm.

Thus, MoS₂ flower-like nanoparticles were synthesized using the hydrothermal method. By impedance spectroscopy, it was shown that the produced sensor layers can detect volatile organic compounds in air at room temperature.