Design and Fabrication of Liquid Pressure Sensor using FBG Sensor through Seesaw Hinge Mechanism

Pressure sensors are used in various industrial applications assisting in preventing unintended disasters. This paper presents the design and fabrication of a novel Seesaw device incorporating a diaphragm and Fiber Bragg Grating (FBG) sensor to measure the pressure of liquids. The designed sensor has been tested in a static water column. The proposed design enables the user to easily make and modify the diaphragm based on the required pressure range without interfering with the FBG sensor. The developed pressure sensor produces improved accuracy and sensitivity to applied liquid pressure in both low and high-pressure ranges without requiring sophisticated sensor construction. A finite element analysis has been performed on the diaphragm and on the entire structure at 10 bar pressure. The deformation of the diaphragm is comparable to theoretical deformation levels. A copper diaphragm with a thickness of 0.25 mm is used in the experiments. All experiments are performed in the elastic region of the diaphragm. The sensor’s sensitivity as 19.244 nm/MPa with the linearity of 99.64% is obtained based on the experiments. Also, the proposed sensor’s performance is compared with recently reported pressure sensors.publishedVersio

Wearable sensors for respiration monitoring: a review

This paper provides an overview of flexible and wearable respiration sensors with emphasis on their significance in healthcare applications. The paper classifies these sensors based on their operating frequency distinguishing between high-frequency sensors, which operate above 10 MHz, and low-frequency sensors, which operate below this level. The operating principles of breathing sensors as well as the materials and fabrication techniques employed in their design are addressed. The existing research highlights the need for robust and flexible materials to enable the development of reliable and comfortable sensors. Finally, the paper presents potential research directions and proposes research challenges in the field of flexible and wearable respiration sensors. By identifying emerging trends and gaps in knowledge, this review can encourage further advancements and innovation in the rapidly evolving domain of flexible and wearable sensors.This work was supported by the Spanish Government (MICINN) under Projects TED2021-131209B-I00 and PID2021-124288OB-I00.Peer ReviewedPostprint (published version

Serially Connected Cantilever Beam-Based FBG Accelerometers: Design, Optimization and Testing

We focus on the design, optimization, fabrication, and testing of fiber Bragg grating (FBG) cantilever beam-based accelerometers to measure vibrations from active seismic sources in the external environment. These FBG accelerometers possess several advantages, such as multiplexing, immunity to electromagnetic interference, and high sensitivity. Finite Element Method (FEM) simulations, calibration, fabrication, and packaging of the simple cantilever beam-based accelerometer based on polylactic acid (PLA) are presented. The influence of the cantilever beam parameters on the natural frequency and sensitivity are discussed through FEM simulation and laboratory calibration with vibration exciter. The test results show that the optimized system has a resonance frequency of 75 Hz within a measuring range of 5–55 Hz and high sensitivity of ±433.7 pm/g. Finally, a preliminary field test is conducted to compare the packaged FBG accelerometer and standard electromechanical 4.5-Hz vertical geophones. Active-source (seismic sledgehammer) shots are acquired along the tested line, and both systems’ experimental results are analyzed and compared. The designed FBG accelerometers demonstrate suitability to record the seismic traces and to pick up the first arrival times. The system optimization and further implementation offer promising potential for seismic acquisitions

Feasibility Analysis of Embedding Optical Fiber Sensor Into Additively Manufactured Part

The research tried to examine the viability of the embedment of optical fiber sensors in Additively built components, packaging the sensors within the components, and characterizing the sensors for sensing a specified measurement. Optical fiber sensors are popular due to their small size, resilience against electromagnetic radiation, and reliability in potentially dangerous conditions. Embedding fibers inside a product allows for the monitoring of critical areas, allowing for preemptive action in the case of a breakdown. Coupons of Inconel 718 were made using laser powder-bed fusion (LPBF), with the fabrication settings tuned to determine whether such a development was possible. After the FBG sensors were inserted in the channel, thermal epoxy was injected to seal the package. After the sample specimen was created, they were put through some tests like fatigue and thermal tests to determine their properties. This was done so that designers in the future would have a road map to follow when creating such a component, and so that we could learn whether the design was viable in general

Permanently-Installed Distributed Pressure Sensors for Downhole Applications

Technology advancements (e.g., hydraulic fracturing and horizontal drilling) to recover unconventional oil and gas (UOG) resources are critical in maintaining future U.S. oil and gas production levels. Permanently installed distributed downhole pressure sensors could monitor fracture propagation, assess the effectiveness of hydraulic fracturing, and optimize hydraulic fracturing placement so that overall UOG recovery efficiency can be increased. However, the harsh environment (high temperatures, high pressures, strong vibration, and presence of brine, mud, debris, hydrate, and various gases), the long data telemetry distance, and the requirements of reliability and service lifetime make the downhole monitoring a very challenging task. To combat these challenges, this thesis presents three sensing systems for downhole pressure monitoring. First, A microwave-photonic low-coherence interferometry (MPLCI) system is proposed for optical fiber based distributed sensing. The system can be used to interrogate the intrinsic Fabry–Pérot interferometers (IFPIs) based distributed downhole pressure sensors. Assisted by an unbalanced Michelson interferometer (MI), a low-coherence laser source is used to interrogate IFPIs along with an optical fiber for a dark zone-free (or spatially continuous) distributed measurement. By combining the advantages of microwaves and photonics, the MPLCI system can synergistically achieve high sensitivity and high spatial resolution. Second, to solve the packaging and drift problems in optical fiber sensors, an all-digital sensing method based on an electrical encoder is developed for downhole pressure monitoring. The key innovation of the all-digital sensor concept is the built-in nonelectric analog-to-digital converter (ADC), which eliminates the need for downhole electronics for signal conditioning and telemetry in conventional electrical downhole sensors. As such, the sensors are more robust, less expensive, and have less drift in comparison with the existing sensors. Because the sensor outputs are digital in nature, the developed sensors can be remotely logged over a long distance, and many sensors can be digitally multiplexed for distributed sensing using a single surface instrument. The all-digital pressure sensors and their surface instrument were designed, engineered, fabricated, and calibrated. The integrated sensing system was tested/validated at both laboratory and research wellbores. Third, to solve the hysteresis problem induced by the electrical encoder, a non-contact optical encoder based all-digital pressure sensor for downhole applications is proposed. The proposed sensor combines the advantages of both optical fiber and all-digital sensing method. The noncontact-type encoder, which is composed of an encoding pad and an all-glass optical fiber sensing head. A glass additive and subtractive manufacturing (ASM) system was used to embed the multi-channel optical fibers into a bulk-fused silica glass substrate with high positioning accuracy and good thermal stability even at elevated temperatures. The optical fiber only serves as the telemetry channel to directly transmit the data in digital format, such that the system has long-distance telemetry capability as well as low drift. The proposed pressure sensor was manufactured and experimentally verified to have a high SNR, linear pressure response, and good long-term stability. In addition, a mathematical model to study the relationships between the sensor’s performances and design parameters was established

Sensores de fibra ótica para arquiteturas e-Health

In this work, optical fiber sensors were developed and optimized for biomedical applications in wearable and non-intrusive and/or invisible solutions. As it was intended that the developed devices would not interfere with the user's movements and their daily life, the fibre optic sensors presented several advantages when compared to conventional electronic sensors, among others, the following stand out: size and reduced weight, biocompatibility, safety, immunity to electromagnetic interference and high sensitivity. In a first step, wearable devices with fibre optic sensors based in Fiber Bragg gratings (FBG) were developed to be incorporated into insoles to monitor different walking parameters based on the analysis of the pressure exerted on several areas of the insole. Still within this theme, other sensors were developed using the same sensing technology, but capable of monitoring pressure and shear forces simultaneously. This work was pioneering and allowed monitoring one of the main causes of foot ulceration in people with diabetes: shear. At a later stage, the study focused on the issue related with the appearance of ulcers in people with reduced mobility and wheelchair users. In order to contribute to the mitigation of this scourge, a system was developed composed of a network of fibre optic sensors capable of monitoring the pressure at various points of the wheelchair. It not only measures the pressure at each point, but also monitors the posture of the wheelchair user and advises him/her to change posture regularly to reduce the probability of this pathology occurring. Still within this application, another work was developed where the sensor not only monitored the pressure but also the temperature in each of the analysis points, thus indirectly measuring shear. In another phase, plastic fibre optic sensors were studied and developed to monitor the body posture of an office chair user. Simultaneously, software was developed capable of monitoring and showing the user all the acquired data in real time and warning for incorrect postures, as well as advising for work breaks. In a fourth phase, the study focused on the development of highly sensitive sensors embedded in materials printed by a 3D printer. The sensor was composed of an optical fibre with a FBG and the sensor body of a flexible polymeric material called "Flexible". This material was printed on a 3D printer and during its printing the optical fibre was incorporated. The sensor proved to be highly sensitive and was able to monitor respiratory and cardiac rate, both in wearable solutions (chest and wrist) and in "invisible" solutions (office chair).Neste trabalho foram desenvolvidos e otimizados sensores em fibra ótica para aplicações biomédicas em soluções vestíveis e não intrusivas/ou invisíveis. Tendo em conta que se pretende que os dispositivos desenvolvidos não interfiram com os movimentos e o dia-a-dia do utilizador, os sensores de fibra ótica apresentam inúmeras vantagens quando comparados com os sensores eletrónicos convencionais, de entre várias, destacam-se: tamanho e peso reduzido, biocompatibilidade, segurança, imunidade a interferências eletromagnéticas e elevada sensibilidade. Numa primeira etapa, foram desenvolvidos dispositivos vestíveis com sensores de fibra ótica baseados em redes de Bragg (FBG) para incorporar em palmilhas de modo a monitorizar diferentes parâmetros da marcha com base na análise da pressão exercida em várias zonas da palmilha. Ainda no âmbito deste tema, adicionalmente, foram desenvolvidos sensores utilizando a mesma tecnologia de sensoriamento, mas capazes de monitorizar simultaneamente pressão e forças de cisalhamento. Este trabalho foi pioneiro e permitiu monitorizar um dos principais responsáveis pela ulceração dos pés em pessoas com diabetes: o cisalhamento. Numa fase posterior, o estudo centrou-se na temática relacionada com o aparecimento de úlceras em pessoas com mobilidade reduzida e utilizadores de cadeiras de rodas. De modo a contribuir para a mitigação deste flagelo, procurou-se desenvolver um sistema composto por uma rede de sensores de fibra ótica capaz de monitorizar a pressão em vários pontos de uma cadeira de rodas e não só aferir a pressão em cada ponto, mas monitorizar a postura do cadeirante e aconselhá-lo a mudar de postura com regularidade, de modo a diminuir a probabilidade de ocorrência desta patologia. Ainda dentro desta aplicação, foi publicado um outro trabalho onde o sensor não só monitoriza a pressão como também a temperatura em cada um dos pontos de análise, conseguindo aferir assim indiretamente o cisalhamento. Numa outra fase, foi realizado o estudo e desenvolvimento de sensores de fibra ótica de plástico para monitorizar a postura corporal de um utilizador de uma cadeira de escritório. Simultaneamente, foi desenvolvido um software capaz de monitorizar e mostrar ao utilizador todos os dados adquiridos em tempo real e advertir o utilizador de posturas incorretas, bem como aconselhar para pausas no trabalho. Numa quarta fase, o estudo centrou-se no desenvolvimento de sensores altamente sensíveis embebidos em materiais impressos 3D. O sensor é composto por uma fibra ótica com uma FBG e o corpo do sensor por um material polimérico flexível, denominado “Flexible”. O sensor foi impresso numa impressora 3D e durante a sua impressão foi incorporada a fibra ótica. O sensor demonstrou ser altamente sensível e foi capaz de monitorizar frequência respiratória e cardíaca, tanto em soluções vestíveis (peito e pulso) como em soluções “invisíveis” (cadeira de escritório).Programa Doutoral em Engenharia Físic