scholarly journals Dynamic Characterisation of Fibre-Optic Temperature Sensors for Physiological Monitoring

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 221
Author(s):  
Joanna M. Coote ◽  
Ryo Torii ◽  
Adrien E. Desjardins
Keyword(s):  
Flow Measurement ◽  
Biomedical Applications ◽  
Temperature Sensors ◽  
Transfer Model ◽  
Thermal Treatments ◽  
Fibre Optic ◽  
The Finite Element Method ◽  
Fibre Optics ◽  
Optical Heating ◽  
Thermal Techniques

Fast, miniature temperature sensors are required for various biomedical applications. Fibre-optics are particularly suited to minimally invasive procedures, and many types of fibre-optic temperature sensors have been demonstrated. In applications where rapidly varying temperatures are present, a fast and well-known response time is important; however, in many cases, the dynamic behaviour of the sensor is not well-known. In this article, we investigate the dynamic response of a polymer-based interferometric temperature sensor, using both an experimental technique employing optical heating with a pulsed laser, and a computational heat transfer model based on the finite element method. Our results show that the sensor has a time constant on the order of milliseconds and a −6 dB bandwidth of up to 178 Hz, indicating its suitability for applications such as flow measurement by thermal techniques, photothermal spectroscopy, and monitoring of thermal treatments.

YAG : R3+ (R = Ce, Dy, Yb) nanophosphor-based luminescent fibre-optic sensors for temperature measurements in the range 20–500 °C

2022 ◽  
Vol 52 (1) ◽  
pp. 94-99
Author(s):  
S K Evstropiev ◽  
V V Demidov ◽  
D V Bulyga ◽  
R V Sadovnichii ◽  
G A Pchelkin ◽  
...  
Keyword(s):  
Thermal Quenching ◽  
Signal Amplitude ◽  
Temperature Sensors ◽  
Yttrium Aluminium Garnet ◽  
Optical Fibres ◽  
Fibre Optic ◽  
Excitation Light ◽  
Yttrium Aluminium ◽  
Increasing Temperature ◽  
Silica Capillary

Abstract We report the development of a group of luminescent fibre-optic temperature sensors that use Ce3+-, Dy3+-, and Yb3+-doped yttrium aluminium garnet (YAG) nanophosphors as thermosensitive materials. The nanophosphors have been prepared in the form of powders with a crystallite size from 19 to 27 nm by a polymer ? salt method and exhibit bright luminescence at 550 (YAG : Ce3+), 400, 480 (YAG : Dy3+), and 1030 nm (YAG : Yb3+). The sensor design includes a silica capillary, partially filled with a nanophosphor, and two large-aperture multimode optical fibres located in the capillary, which deliver excitation light and receive and transmit the photoluminescence signal. The photoluminescence signal amplitude of all the sensors decreases exponentially with increasing temperature, pointing to characteristic thermal quenching of photoluminescence and adequate operation of the devices up to 500 °C. The highest temperature sensitivity among the fibre-optic sensors is offered by the YAG : Ce3+ nanophosphor-based devices.

scholarly journals A 1D Model for Predicting Heat and Moisture Transfer through a Hemp-Concrete Wall Using the Finite-Element Method

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6903
Author(s):  
Maroua Benkhaled ◽  
Salah-Eddine Ouldboukhitine ◽  
Amer Bakkour ◽  
Sofiane Amziane
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Moisture Transfer ◽  
Construction Material ◽  
Climatic Conditions ◽  
Vapor Permeability ◽  
Transfer Model ◽  
The Finite Element Method ◽  
Concrete Wall ◽  
Element Method

Plant-based concrete is a construction material which, in addition to having a very low environmental impact, exhibits excellent hygrothermal comfort properties. It is a material which is, as yet, relatively unknown to engineers in the field. Therefore, an important step is to implement reliable mass-transfer simulation methods. This will make the material easy to model, and facilitate project design to deliver suitable climatic conditions. In recent decades, numerous studies have been carried out to develop models of the coupled transfers of heat, air and moisture in porous building envelopes. Most previous models are based on Luikov’s theory, considering mass accumulation, air and total pressure gradient. This theory considers the porous medium to be homogeneous, and therefore allows for hygrothermal transfer equations on the basis of the fundamental principles of thermodynamics. This study presents a methodology for solving the classical 1D (one-dimensional) HAM (heat, air, and moisture) hygrothermal transfer model with an implementation in MATLAB. The resolution uses a discretization of the problem according to the finite-element method. The detailed solution has been tested on a plant-based concrete. The energy and mass balances are expressed using measurable transfer quantities (temperature, water content, vapor pressure, etc.) and coefficients expressly related to the macroscopic properties of the plant-based concrete (thermal conductivity, specific heat, water vapor permeability, etc.), determined experimentally. To ensure this approach is effective, the methodology is validated on a test case. The results show that the methodology is robust in handling a rationalization of the model whose parameters are not ranked and not studied by their degree of importance.

Characterization and Modeling of Micro Swimmers With Helical Tails and Cylindrical Heads Inside Circular Channels

2013 ◽  
Author(s):  
Alperen Acemoglu ◽  
F. Zeynep Temel ◽  
Serhat Yesilyurt
Keyword(s):  
Biomedical Applications ◽  
Stokes Equations ◽  
Relative Size ◽  
The Finite Element Method ◽  
Robot Interaction ◽  
Free Swimming ◽  
Micro Robot ◽  
Angular Velocities ◽  
Minimal Damage ◽  
Surgical Operations

Micro swimming robots offer many advantages in biomedical applications, such as delivering potent drugs to specific locations in targeted tissues and organs with limited side effects, conducting surgical operations with minimal damage to healthy tissues, treatment of clogged arteries, and collecting biological samples for diagnostic purposes. Reliable navigation techniques for micro swimmers need to be developed to improve the localization of robots inside the human body in future biomedical applications. In order to estimate the dynamic trajectory of magnetically propelled micro swimmers in channels, that mimic blood vessels and other conduits, fluid-micro robot interaction and the effect of the channel wall must be understood well. In this study, swimming of one-link robots with helical tails is modeled with Stokes equations and solved numerically with the finite element method. Forces acting on the robot are set to zero to enforce the force-free swimming and obtain forward, lateral and angular velocities that satisfy the constraints. Effects of the number of helical waves, wave amplitude, relative size of the cylindrical head of micro swimmer and the radial position on angular and linear velocity vectors of micro swimmer are presented.

Amorphous Silicon Temperature Sensors Integrated with Thin Film Heaters for Thermal Treatments of Biomolecules

2017 ◽  
pp. 183-193
Author(s):  
Nicola Lovecchio ◽  
Domenico Caputo ◽  
Giulia Petrucci ◽  
Augusto Nascetti ◽  
Marco Nardecchia ◽  
...  
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Temperature Sensors ◽  
Thermal Treatments

Estimation of the Heat Flux Through Furnace Side Walls Protected with Water Cooled Cooling Devices

2007 ◽  
Vol 553 ◽  
pp. 130-135
Author(s):  
Gabriel Plascencia ◽  
Torstein A. Utigard ◽  
Juliana Gutiérrez ◽  
David Jaramillo ◽  
Vicente Mayagoitia ◽  
...  
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Three Dimensional ◽  
Transfer Model ◽  
The Finite Element Method ◽  
Numerical Heat Transfer ◽  
Cooling Devices ◽  
Side Walls ◽  
Set Up ◽  
The Mathematical Model

A three dimensional numerical heat transfer model has been developed to estimate the heat flux trough furnace side walls protected with water cooled cooling fingers. The model was set up by means of the finite element method. Materials with different thermal conductivity were modelled and the results obtained with the mathematical model were compared with experimental data. In every case, it was found excellent agreement between the experimental data and the model computations.

Sign in / Sign up

Export Citation Format

Share Document