Search Results (6)

Flexible sensors can measure various stimuli owing to their exceptional flexibility, stretchability, and electrical properties. However, the integration of multiple stimuli into a single sensor for measurement is challenging. To address this issue, the sensor developed in this study utilizes the natural biopolymers sodium alginate and carboxymethyl cellulose to construct a dual interpenetrating network, This results in a flexible porous sponge that exhibits a dual-modal response to strain and magnetic stimulation. The dual-mode flexible sensor achieved a maximum tensile strength of 429 kPa and elongation at break of 24.7%. It also exhibited rapid response times and reliable stability under both strain and magnetic stimuli. The porous foam sensor is intended for use as a wearable electronic device for monitoring joint movements of the body. It provides a swift and stable sensing response to mechanical stimuli arising from joint activities, such as stretching, compression, and bending. Furthermore, the sensor generates opposing response signals to strain and magnetic stimulation, enabling real-time decoupling of different stimuli. This study employed a simple and environmentally friendly manufacturing method for the dual-modal flexible sensor. Because of its remarkable performance, it has significant potential for application in smart wearable electronics and artificial electroskins. Full article

Urban environments are undergoing significant transformations, with pedestrian areas emerging as complex hubs of diverse mobility modes. This shift demands a more nuanced approach to urban planning and navigation technologies, highlighting the limitations of traditional, road-centric datasets in capturing the detailed dynamics of pedestrian spaces. In response, we introduce the DELTA dataset, designed to improve the analysis and mapping of pedestrian zones, thereby filling the critical need for sidewalk-centric multimodal datasets. The DELTA dataset was collected in a single urban setting using a custom-designed modular multi-sensing e-scooter platform encompassing high-resolution and synchronized audio, visual, LiDAR, and GNSS/IMU data. This assembly provides a detailed, contextually varied view of urban pedestrian environments. We developed three distinct pedestrian route segmentation models for various sensors—the 4K camera, stereocamera, and LiDAR—each optimized to capitalize on the unique strengths and characteristics of the respective sensor. These models have demonstrated strong performance, with Mean Intersection over Union (IoU) values of 0.84 for the reflectivity channel, 0.96 for the 4K camera, and 0.92 for the stereocamera, underscoring their effectiveness in ensuring precise pedestrian route identification across different resolutions and sensor types. Further, we explored audio event-based classification to connect unique soundscapes with specific geolocations, enriching the spatial understanding of urban environments by associating distinctive auditory signatures with their precise geographical origins. We also discuss potential use cases for the DELTA dataset and the limitations and future possibilities of our research, aiming to expand our understanding of pedestrian environments. Full article

Recently, flexible sensors have gained significant attention due to their potential applications in soft robotics and biomimetic intelligent devices. However, the successful production of favorable flexible sensors integrated with high flexibility, sensitivity and excellent environment adaptability toward multiple external stimuli is still an enormous challenge. Herein, a lightweight polymeric porous sponge capable of detecting an external magnetic field and strain excitations is proposed by assembling a sodium alginate/chitosan (SA/CHI) porous sponge with micron carbonyl iron and nanoscale Fe₃O₄ magnetic particles (MPs). Based on the double network structure, the SA/CHI sponge possesses preferable mechanical strength and hydrophilicity, demonstrating its high flexibility and deformability. More importantly, the electrical response of the SA/CHI sponge sensors can display remarkable variation under external magnetic and mechanical stimuli due to their superior magnetic characteristics and electrical conductivity. Meanwhile, their sensing properties can maintain relatively stable recoverability and repeatability towards the periodic excitations and releases. Additionally, a potential mechanism is provided to investigate their stimuli-sensitive behavior. It is highly dependent on the microstructure variations in MPs and conductive multi-walled carbon nanotube (MWCNTs) networks. Due to its exceptional magnetic controllability and appropriate electrical sensitivity, the proposed sensor shows high potential in wearable multi-sensing electronics and intelligent transport devices. Full article

In this article, a multi-sensing technique on surface-mounted PZT sensors is proposed. The investigation was performed on concrete structures to detect and localize structural damage. Multiple smart sensing units (SSU) were adhesively bonded on the top surface of a concrete beam. As each PZT sensor features a small zone of influence, the use of multiple smart sensors is recommended for effective damage detection. The conductance signatures were obtained at different stages in the frequency range of 0–450 kHz. This article also presents an effective methodology for damage localization, which assumes the parallel connection of SSUs in MISO mode. The methodology adopted for structural damage detection is effective, as it is verified by the experimental results performed on concrete structures with multiple surface-mounted PZT sensors. Full article

In this paper, an approach to measure both the refractive index (RI) and the pressure simultaneously using two Whispering-Gallery Modes (WGMs) in a microdisk resonator is theoretically proposed. Due to the difference in the energy distribution of the first and second order WGMs, the sensitivity of two modes toward the variation of RI and pressure applied to the device show differences. An RI sensitivity of 29.07 nm/RIU and pressure sensitivity of 0.576 pm/kPa for WGM (1,36), and an RI sensitivity of 38.68 nm/RIU and a pressure sensitivity of 0.589 pm/kPa for WGM (2,28) are obtained through the 3D finite-difference time-domain (3D-FDTD) simulation. Dual parametric sensing can be achieved by solving the second-order inverse sensitivity matrix. Therefore, strain–optical coupling behavior is effectively eliminated. The dual sensing scheme we proposed provides a novel approach to overcome the difficulty of multi-sensing applications based on the flexible photonic device. Full article

A novel optical fiber array-type of sensing instrument with temperature compensation for real-time detection was developed to measure oxygen, carbon dioxide, and ammonia simultaneously. The proposed instrument is multi-sensing array integrated with real-time measurement module for portable applications. The sensing optical fibers were etched and polished before coating to increase sensitivities. The ammonia and temperature sensors were each composed of a dye-coated single-mode fiber with constructing a fiber Bragg grating and a long-period filter grating for detecting light intensity. Both carbon dioxide and oxygen sensing structures use multimode fibers where 1-hydroxy-3,6,8-pyrene trisulfonic acid trisodium salt is coated for carbon dioxide sensing and Tris(2,2′-bipyridyl) dichlororuthenium(II) hexahydrate and Tris(bipyridine)ruthenium(II) chloride are coated for oxygen sensing. Gas-induced fluorescent light intensity variation was applied to detect gas concentration. The portable gas sensing array was set up by integrating with photo-electronic measurement modules and a human-machine interface to detect gases in real time. The measured data have been processed using piecewise-linear method. The sensitivity of the oxygen sensor were 1.54%/V and 9.62%/V for concentrations less than 1.5% and for concentrations between 1.5% and 6%, respectively. The sensitivity of the carbon dioxide sensor were 8.33%/V and 9.62%/V for concentrations less than 2% and for concentrations between 2% and 5%, respectively. For the ammonia sensor, the sensitivity was 27.78%/V, while ammonia concentration was less than 2%. Full article