Browsing by Subject "Wireless monitoring"

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Open Access
Development of a distance-independent wireless passive RF resonator sensor and a new telemetric measurement technique for wireless strain monitoring
(Elsevier B.V., 2017) Alipour, A.; Unal, E.; Gokyar, S.; Demir, Hilmi Volkan
We proposed and developed a novel wireless passive RF resonator scheme that enables telemetric strain sensing avoiding the need for calibration at different interrogation distances. The specific architecture of the proposed structure allows for strong inductive coupling and, thus, a higher wireless signal-to-noise ratio. Here, in operation, the frequency scan of the sensor impedance was used to measure simultaneously both the impedance amplitude and resonance frequency. Using this wireless sensor, we further introduced a new telemetric monitoring modality that employs full electrical characteristics of the system to achieve correct strain extraction at any interrogation distance. In principle, any deformation of the sensor structure results in the resonance frequency shift to track strain. However, changing of the interrogation distance also varies the inductive coupling between the sensor and its pick-up antenna at the interrogation distance. Therefore, at varying interrogation distances, it is not possible to attribute an individual resonance frequency value solely to an individual strain level, consequently resulting in discrepancies in the strain extraction if the interrogation distance is not kept fixed or distance-specific calibration is not used. In this work, we showed that by using both the proposed passive sensor structure and wireless measurement technique, strain can be successfully extracted independent of the interrogation distance for the first time. The experimental results indicate high sensitivity and linearity for the proposed system. These findings may open up new possibilities in applications with varying interrogation distance for mobile wireless sensing. © 2017 Elsevier B.V.
Embargo
Self-poled piezoelectric nanocomposite fiber sensors for wireless monitoring of physiological signals
(American Chemical Society, 2024-06-28) Hasan, Md Mehdi; Rahman, Mahmudur; Sadeque, Md Sazid; Ordu, Mustafa
Self-powered sensors have the potential to enable real-time health monitoring without contributing to the ever-growing demand for energy. Piezoelectric nanogenerators (PENGs) respond to mechanical deformations to produce electrical signals, imparting a sensing capability without external power sources. Textiles conform to the human body and serve as an interactive biomechanical energy harvesting and sensing medium without compromising comfort. However, the textile-based PENG fabrication process is complex and lacks scalability, making these devices impractical for mass production. Here, we demonstrate the fabrication of a long-length PENG fiber compatible with industrial-scale manufacturing. The thermal drawing process enables the one-step fabrication of self-poled MoS2-poly(vinylidene fluoride) (PVDF) nanocomposite fiber devices integrated with electrodes. Heat and stress during thermal drawing and MoS2 nanoparticle addition facilitate interfacial polarization and dielectric modulation to enhance the output performance. The fibers show a 57 and 70% increase in the output voltage and current compared to the pristine PVDF fiber, respectively, at a considerably low MoS2 loading of 3 wt %. The low Young's modulus of the outer cladding ensures an effective stress transfer to the piezocomposite domain and allows minute motion detection. The flexible fibers demonstrate wireless, self-powered physiological sensing and biomotion analysis capability. The study aims to guide the large-scale production of highly sensitive integrated fibers to enable textile-based and plug-and-play wearable sensors.