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Multi-parameter sensing technology plays an important role in structural health monitoring. In this paper, a novel FBG sensor with a pendulum structure for simultaneous measurement of tilt and acceleration is proposed. The design, principle and performance of the FBG sensor is introduced and tested in detail. The results show that the tilt sensitivity and acceleration sensitivity of the proposed FBG sensor can reach 408.3 pm/° and 2.43 nm/(m/s2), respectively, and that it works below 32 Hz in weak vibration detection. The theory analysis and the test result are in good agreement with each other. A wavelet transform method is utilized to separate the tilt and acceleration from the original signal received by the proposed FBG sensor. Cross sensitization of tilt and acceleration can be avoided effectively using this method. Finally, a field test is conducted in a railway slope. The recorded data is analyzed, which confirms further that the proposed FBG sensor can detect tilt and acceleration simultaneously. This novel FBG sensor provides a new method for multi-parameter monitoring.

The advancement of age and the increased awareness of public health have resulted in increased demand for continuous vital sign monitoring devices. Therefore, we developed a noninvasive vital sign measurement device without physical resistance to the user using a fiber Bragg grating (FBG) sensor. The FBG sensor was fixed on the wrist, and a pulse wave signal was obtained. Additionally, we focused on the similarity between this pulse wave signal and the second derivative of the plethysmogram (SDPTG). Classifying this signal, we found that its shape changed according to the age and blood pressure. We found that the change in the shape of the pulse wave signal and the SDPTG have the same tendency. Therefore, it is feasible to estimate the vascular age and arteriosclerosis with the signal obtained by an FBG sensor. On the basis of these results, the FBG sensor system can measure multiple vital signs and monitor health more comprehensively.

We are working on the development of a sensor that can calculate various vital signs from the signals measured by installing a Fiber Bragg Grating (FBG) sensor at the pulsation point of a living body. In this paper, the influence of blood flow parameters and sensor installation conditions on the FBG sensor signal was verified using two blood flow simulation models. From the results of our study, the following observations were made. The fluid pressure increases, the wavelength shift of the FBG sensor beca me larger. By contrast, an increase in the viscosity of the fluid was seen to cause a decrease in the displacement length of the Bragg wavelength. Fluid pressure and viscosity were observed to opposite effects on the FBG sensor signal. The Bragg wavelength shift of the FBG sensor was observed to be larger when the installation direction of the FBG sensor was perpendicular to the blood flow direction than in the parallel direction. However, FBG sensor signals with higher signal-to-noise (S/N) ratio were measured at an angle of 75 degrees than at an angle of 90 degrees, which is perpendicular to the blood flow direction. From the above results, the installation condition of the FBG sensor on the measurement signal and the influence of each parameter of blood flow were established.

Structural health monitoring (SHM) of engineering structures plays a crucial role in ensuring their safety and integrity. Acoustic emissions (AE) can be one of the several ways to monitor the structural health. Fiber Bragg grating (FBG)-based AE measurement technique is emerging as a solution to assess cracks in structures remotely and has advantages of being less bulky and having low noise, high bandwidth and ease of implementation. This paper presents a study on the impact of AE signals on FBGs attached to a substrate, focusing on the directional sensitivity using different configurations. For ease of installation, the FBG sensors are metallically packaged similar to lead zirconium titanate (PZT) sensors in which they can withstand temperatures of up to 250 °C. The directional AE sensitivity of the packaged FBG sensor device is studied and compared with that of a surface attached FBG. Experimentally, the AE signals are generated by a metal ball drop impact on aluminum plate and are measured using an FBG AE interrogation system. A numerical simulation of the design was carried out using ANSYS explicit dynamics and the AE wave propagation in structure was analyzed and experimentally verified.

The deployment of the spinal needle of an appropriate gauge is highly essential in order to significantly reduce the side effects of lumbar puncture procedures performed for spinal anaesthesia and spinal surgeries. The gauge of the spinal needle used for the procedure plays a significant role in determining the force required for its insertion into the tissue and is chosen by the medical practitioner performing the procedure based on the expertise. The selection of the optimum gauge of the needle is subjective to the level of discretion exercised by the surgeon. This paper shows a comparative analysis of the force required for lumbar puncture with various tissue layers traversal by four different gauges of the spinal needle, making use of a real time dynamic force monitoring device which employs a fiber Bragg grating sensor. The fiber Bragg grating (FBG) force device (FBGFD) is used to measure the force variations on different gauges of spinal needle during the lumbar puncture procedure performed first on a simulator model and subsequently on a human cadaver specimen. The FBGFD facilitates dynamic measurement of force variation on the spinal needle during the penetration by the sensing bar mechanism which is acquired by the FBG sensor bonded over it with a resolution of 0.021 N. This comparative study of force may serve as a guideline for selection of proper gauge spinal needle during tissue puncture procedures minimizing post puncture effects on patients.

This paper presents a photonic system based on Fiber Bragg Gratings (FBGs) for application to wearable garments. The objective is spanning the FBGs over the whole area of the garments for acting as sensing elements. The FBGs are embedded on a polychloroethanediyl (polyvinyl chloride, commonly abbreviated as PVC) carrier in order to increase their sensitivity to strains and for improving the simultaneous acquisition of respiratory and cardiac frequencies with only one FBG sensor. The global structure comprising FBGs and carrier allow high strain cycles and at the same time present linear behavior with the temperature, 17 pm º C -1. The measurements show a stable structure for temperatures up to 100 º C. This brings excellent perspectives for measuring the temperature with high accuracy and range. A set of tests were done by subjecting the FBG/carrier structure (with FBG stretched and no curves) to strains up to 1.2 mm, and it was also observed a linear behaviour: e.g., displacements of 0.8 pm εμ-¹. Behind its sensing enhancement operation, the carrier makes easy to mount the sensing structures., (/0025/2008)