Research on the influence of dimension and location of reflective film on the resonance frequency of quartz tuning fork

We studied the effected of dimension and location of reflective film on the resonance frequency. Simulation results indicate that the location of reflective film has a greater impact on the resonance frequency of QTF. The higher the position of reflective film, the lower the resonance frequency of QTF. Furthermore, the resonance frequency can also be affected by the dimension of reflective film. However, the reflective film in the middle of the QTF arm is not sensitive to the dimension of reflective film. The frequency is close to the resonance frequency of the QTF model without reflective film, it is about 30259Hz. We can increase the length and width of reflective film to improve the laser reflection on the QTF surface. Therefore, this position is suitable for the detection of photo-acoustic spectroscopy. The analysis results provide a theoretical basis for researching new photo-acoustic spectrum remote sensing device

Recent Developments in Modulation Spectroscopy for Methane Detection Based on Tunable Diode Laser

In this review, methane absorption characteristics mainly in the near-infrared region and typical types of currently available semiconductor lasers are described. Wavelength modulation spectroscopy (WMS), frequency modulation spectroscopy (FMS), and two-tone frequency modulation spectroscopy (TTFMS), as major techniques in modulation spectroscopy, are presented in combination with the application of methane detection

Research on the influence of dimension and location of reflective film on the resonance frequency of quartz tuning fork

We studied the effected of dimension and location of reflective film on the resonance frequency. Simulation results indicate that the location of reflective film has a greater impact on the resonance frequency of QTF. The higher the position of reflective film, the lower the resonance frequency of QTF. Furthermore, the resonance frequency can also be affected by the dimension of reflective film. However, the reflective film in the middle of the QTF arm is not sensitive to the dimension of reflective film. The frequency is close to the resonance frequency of the QTF model without reflective film, it is about 30259Hz. We can increase the length and width of reflective film to improve the laser reflection on the QTF surface. Therefore, this position is suitable for the detection of photo-acoustic spectroscopy. The analysis results provide a theoretical basis for researching new photo-acoustic spectrum remote sensing device

Development of a Robotic Arm Based Hydrogel Additive Manufacturing System for In-Situ Printing

In-situ printing is a promising injury repair technique that can be directly applied during surgical operations. This paper features a potential in-situ printing platform based on a small-scale robotic arm with a micro-sized dispenser valve. A double-light-source curing method was applied to print poly(ethylene glycol) diacrylate (PEGDA) with a 20% (weight/volume) ratio and the entire process was controlled automatically by a computer interface where droplet diameter, curing time, mechanical properties were measured and essential printing parameters (e.g., nozzle velocity, nozzle frequency) were determined. Three different two-dimensional (2D) plane models (namely, square, circular, and heart-shaped) were printed during initial printing trials. The feasibility study of in-situ printing on curved surfaces was tested using a three-dimensional (3D) printed defect model. The defect was successfully filled using both parallel and ring printing paths. In conclusion, the robotic arm printing platform and its forming method can achieve a rapid curing of PEGDA hydrogel on a curved surface and has the potential to be applied to in-situ printing

Coaxial Printing of Silicone Elastomer Composite Fibers for Stretchable and Wearable Piezoresistive Sensors

Despite the tremendous efforts dedicated to developing various wearable piezoresistive sensors with sufficient stretchability and high sensitivity, challenges remain pertaining to fabrication scalability, cost, and efficiency. In this study, a facile, scalable, and low-cost coaxial printing strategy is employed to fabricate stretchable and flexible fibers with a core–sheath structure for wearable strain sensors. The highly viscous silica-modified silicone elastomer solution is used to print the insulating sheath layer, and the silicone elastomer solutions containing multi-walled carbon nanotubes (CNTs) are used as the core inks to print the conductive inner layer. With the addition of silica powders as viscosifiers, silica-filled silicone ink (sheath ink) converts to printable ink. The dimensions of the printed coaxial fibers can be flexibly controlled via adjusting the extrusion pressure of the inks. In addition, the electro-mechanical responses of the fiber-shaped strain sensors are investigated. The printed stretchable and wearable fiber-like CNT-based strain sensor exhibits outstanding sensitivities with gauge factors (GFs) of 1.4 to 2.5 × 106, a large stretchability of 150%, and excellent waterproof performance. Furthermore, the sensor can detect a strain of 0.1% and showed stable responses for over 15,000 cycles (high durability). The printed fiber-shaped sensor demonstrated capabilities of detecting and differentiating human joint movements and monitoring balloon inflation. These results obtained demonstrate that the one-step printed fiber-like strain sensors have potential applications in wearable devices, soft robotics, and electronic skins

State estimation of lithium-ion batteries based on strain parameter monitored by fiber Bragg grating sensors

Multisensory and artificial intelligence approaches are key tools to achieve intelligent management of future battery systems. Strain monitoring using optical fiber sensors is an important role of multi-sensing in batteries. In this paper, the strain of batteries is monitored by fiber Bragg grating sensors, and the strain data are used to estimate the state of charge (SoC) and state of health (SoH) of batteries. A Kalman filtering (KF) model is proposed for SoC estimation based on strain signal of cells. Moreover, this work employs an artificial neural network (NN) for SoC estimation based on the strain data. The experimental data are acquired from commercial lithium-ion cells under two operating conditions. The KF model is established based on multiple regression between strain and SoC, which shows good performance in estimation for the static cycles. For NN estimators, input variables with strain parameter can enhance the accuracy of SoC estimation. A KF model based on the peak strain is developed to estimate the capacity degradation of battery, and the results show that strain can be used as an indicator to estimate SoH. The results present an encouraging outcome that SoC estimation can be achieved using non-electrical parameters solely, and the strain signal can also be used as an auxiliary parameter to improve the accuracy of SoC estimation. This new exploration provides a basis for multi-parameter cooperative estimation of battery state in the future battery system with a multisensory approach.This work was supported by the National Natural Science Foundation of China (52075429 and 92060110) , Natural Science Foundation of Jiangxi Province (20202BAB204019)

Recent Progress on Electromagnetic Field Measurement Based on Optical Sensors

Electromagnetic field sensors are widely used in various areas. In recent years, great progress has been made in the optical sensing technique for electromagnetic field measurement, and varieties of corresponding sensors have been proposed. Types of magnetic field optical sensors were presented, including probes-based Faraday effect, magnetostrictive materials, and magnetic fluid. The sensing system-based Faraday effect is complex, and the sensors are mostly used in intensive magnetic field measurement. Magnetic field optical sensors based on magnetic fluid have high sensitivity compared to that based on magnetostrictive materials. Three types of electric field optical sensors are presented, including the sensor probes based on electric-optic crystal, piezoelectric materials, and electrostatic attraction. The majority of sensors are developed using the sensing scheme of combining the LiNbO3 crystal and optical fiber interferometer due to the good electro-optic properties of the crystal. The piezoelectric materials-based electric field sensors have simple structure and easy fabrication, but it is not suitable for weak electric field measurement. The sensing principle based on electrostatic attraction is less commonly-used sensing methods. This review aims at presenting the advances in optical sensing technology for electromagnetic field measurement, analyzing the principles of different types of sensors and discussing each advantage and disadvantage, as well as the future outlook on the performance improvement of sensors

Spatial-Temporal Changes of Soil Organic Carbon Content in Wafangdian, China

Soil organic carbon (SOC) plays an important role in soil fertility and the global carbon cycle. A better understanding of spatial-temporal changes of SOC content is essential for soil resource management, emission studies, and carbon accounting. In this study, we used a boosted regression trees (BRT) model to map distributions of SOC content in the topsoil (0–20 cm) and evaluated its temporal dynamics from 1990–2010 in Wafangdian City, northeast of China. A set of 110 (1990) and 127 (2010) soil samples were collected and nine environment variables (including topography and vegetation) were used. A 10-fold cross-validation was used to evaluate model performance as well as predictive uncertainty. Accuracy assessments showed that R2 of 0.53 and RMSE (Root-mean-square error) of 9.7 g∙kg−1 for 1990, and 0.55, and 5.2 g∙kg−1 for 2010. Elevation and NDVI (Normalized Difference Vegetation Index) were the two important variables affecting SOC distribution. Results showed that mean SOC content decreased from 19 ± 14 to 18 ± 8 g∙kg−1 over a 20 year period. The maps of SOC represented a decreasing trend from south to north across the study area in both periods. Rapid urbanization and land-use changes were accountable for declining SOC levels. We believe predicted maps of SOC can help local land managers and government agencies to evaluate soil quality and assess carbon sequestration potential and carbon credits

Design and Fabrication of a MEMS Electromagnetic Swing-Type Actuator for Optical Switch

A microelectromechanical systems system (MEMS) electromagnetic swing-type actuator is proposed for an optical fiber switch in this paper. The actuator has a compact size of 5.1 × 5.1 × 5.3 mm3, consisting of two stators, a swing disc (rotator), a rotating shaft, and protective covers. Multi-winding stators and a multipole rotator were adopted to increase the output torque of the actuator. The actuator’s working principle and magnetic circuit were analyzed. The calculation results show that the actuator’s output torque is decisive to the air gap’s magnetic flux density between the stators and the swing disc. NiFe alloy magnetic cores were embedded into each winding center to increase the magnetic flux density. A special manufacturing process was developed for fabricating the stator windings on the ferrite substrate. Six copper windings and NiFe magnetic cores were electroplated onto the ferrite substrates. The corresponding six magnetic poles were configured to the SmCo permanent magnet on the swing disc. A magnetizing device with a particular size was designed and fabricated to magnetize the permanent magnet of the swing disc. The actuator prototype was fabricated, and the performance was tested. The results show that the actuator has a large output torque (40 μNm), fast response (5 ms), and a large swing angle (22°)