Fiber Bragg Grating Sensors in biomedical science

Biomechanical engineering experiences rapid development as a result of FBG sensor application to strain and deformation measurements. The use of fiber Bragg grating sensors in biomedicine is a promising new method of enhancing biomechanical studies.

Fiber Bragg gratings were proposed for use in medical applications at the end of the 20th century. Some of the applications were monitoring ultrasound fields, monitoring the temperature inside nMRI devices, foot pressure monitoring in diabetic patients, etc.

One of the first uses of FBG sensors in biomedicine was an electrically assisted ventilation device triggered by an FBG sensor. A deformable strap was placed on the patient’s chest; the strap had FBG sensors embedded into it that were measuring chest deformations that were caused by air inspiration. A threshold level was set to produce a trigger signal to stimulate the phrenic nerve. Nowadays FBG sensors are used in medical-grade textiles for healthcare monitoring.

Fiber Bragg grating sensors provide several advantages over traditional methods of measuring ligament and tendon deformation and strain, namely an opportunity to record the deformations under several postures. For example, a foot pressure sensing system with embedded FBG was presented; it contains several carefully calibrated FBG sensors in an optical fiber strand. The distribution of transversal pressure and its analysis help to indicate abnormal standing gait in diabetic patients.

The research suggests that FBG sensors are superior to traditionally used strain gauges in soft tissue strain measurement. FBGS easily adhere to a bone or a curved surface; their dimensions are more compatible with bone size than those of the strain gauges; they are easily implantable, highly accurate, and less invasive.

The use of fiber Bragg grating sensors in intervertebral disc pressure measurements is very promising as it is significantly more sensitive than other measuring methods. Moreover, the FBG sensors are more compact which allows them to be inserted through a needle, and to be used for small discs, e.g. cervical or biodegenerated.

Fiber Bragg sensors proved to be useful in a femoral prosthesis. The multiplexing ability of FB sensors allows us to place several sensors on a prosthesis surface and connect them using a single optical link to interrogate all of them. The sensors aid in locating potential failure areas in the prosthesis under normal strain conditions.

Optromix is a fiber Bragg grating sensor vendor; we manufacture innovative fiber optic products for the global market. We are dedicated to delivering the best products and supports to all our customers, our engineers have extensive experience and strong technical expertise in creating fiber Bragg grating products. If you would like to buy FBG strain sensors, please contact us at info@optromix.com.

Real Time Thermal Rating systems

RTTR, or Real-Time Thermal Rating, is a method of assessing real-time operational thermal rating of the equipment, or the amount of electrical current that a power line or an electrical facility can endure before suffering critical damage. Thermal rating devices can be used to measure the temperature of overhead power lines, transformers, underground and subsea cables.

Real-time thermal rating systems rely on real-time data from environmental conditions rather than theoretical assumptions and predictions. These systems are able to not only measure the thermal ratings in real-time but also to measure the stress levels of certain areas and determine their capacity. The calculation of the thermal ratings happen on the basis of: 1) weather conditions; 2) electrical current; 3) temperature of the equipment. However, other factors may need to be considered; this depends on the environment where real-time thermal rating needs to be performed. For example, soil condition, burial depth, and configuration must be considered for temperature measurement of underground cables, the mass of the transformer and type of the cooling mechanisms for temperature measurement of transformers, etc.

The key to the real-time thermal rating system, the temperature of the asset, should be continuously measured to avoid heating of the asset to dangerous levels. Distributed temperature sensing (DTS) systems should be used for this purpose, otherwise, only predictions about the temperature can be made.

The main advantage of real-time thermal rating systems is their ability to accurately measure the thermal behavior of assets, taking into consideration factors that static ratings do not. Static rating calculations are often overly conservative, therefore some power lines are often not used up to their full potential, while others are overloaded, which causes premature aging.

Thermal rating systems may be implemented into different types of power assets. Underground cable monitoring benefits greatly from introducing real-time thermal rating systems as they measure soil ambient temperature and soil thermal resistivity; these measurements help to determine actual thermal headroom to indicate unused network capacity.  

The thermal rating of the overhead power lines, depending on the actual system used, takes either the sag of the lines, the tension of the line conductor, the temperature of the line conductor, or environmental conditions into account during calculation.

Transformer load, ambient and transformer temperatures, oil temperature, and winding hot spot temperature are utilized by RTTR systems for transformers.

DTS optic sensing fibers are important for real-time thermal rating; they are installed along the length of the power cable and provide a continuous temperature profile.

If you would like to purchase DTS (Distributed Temperature System), please contact us: info@optromix.com or +1 617 558 98 58.

Temperature sensors in energy systems

In the modern world, the increasing electricity consumption and high demand for energy lead to an increase in stress on the power cables that often reach their physical limits. This affects the safety of power lines and their efficiency. To combat these issues, real-time thermal ratings may be implemented to observe the thermal behavior of cables and calculate their operational limits. The knowledge of these parameters is key to control the safety and efficiency of power lines, as unforeseeable thermal conditions do, in fact, lead to system degradation and capacity reduction. Real-time thermal rating aid in saving maintenance time, optimization of resources, and improving the efficiency of power lines.

Real-time thermal ratings may not only assist in perfecting already existing energy systems but also to integrate alternative power sources, such as wind energy systems. To improve the wind energy infrastructure and to further integrate renewable energy sources into mainstream energy production, the reduction of restrictions placed on wind energy is necessary for elevating the efficiency of such systems. The following measurements are required in order to implement real-time thermal ratings into the network: wind speed, thermal state estimations, temperature, and voltage measurements. The combination of these variables creates real-time ratings for wind energy systems.

The evaluation of said measurements provides crucial information on the ways in which wind energy capacity may be increased. For example, an implementation of thermal ratings that was conducted in 2010 revealed that the cooling effect of wind significantly affects wind power lines and may potentially lead to an increase in their electrical capacity up to 30%.

These results proved to be significant to the field and provided valuable insight into the generation capacity and its potential increases. It is expected that real-time thermal readings will allow for increased integration of wind energy into the distribution network.

Fiber Bragg temperature sensors are insensitive to changes in the environment, which is important for wind energy generators, and have a long reliability period. If you would like to purchase Optromix FBG Temperature Sensors, please contact us: info@optromix.com or +1 617 558 98 58.

Distributed temperature sensors in experimental hydrology

Distributed temperature sensors are usually used in industrial applications, such as process control and infrastructure monitoring; however, in the past couple of years, fiber optic distributed sensors have been used in ecological monitoring. The ability to measure temperature in time and space simultaneously allows distributed temperature sensors to be used in groundwater detection, rainforest ambient temperature monitoring, stream temperature monitoring, and more.

Temperature sensing is one of the most significant methods of experimental hydrology as it provides valuable insight into the flow dynamics of different types of water bodies. The water temperature is determined by measuring the Stokes/anti-Stokes ratio of reflected light that was produced by sending a laser pulse through the cable. The cable is placed into the body of water to detect temperature fluctuations along the stream. The data density of distributed sensors allows to obtain high-resolution data and map temperature changes in the water with high accuracy, and the absence of electronic parts in monitoring zones makes distributed sensors safe to use underwater. High return speeds of such optic sensors are perfect for both fast-changing and subtle temperature changes that often occur in water. Moreover, distributed temperature sensors are extremely thin and are easy to use in shallow streams and wells, and resistance to corrosion determines their long life cycle even if used in harsh conditions.

The measurements obtained by utilizing distributed temperature sensors are then used to construct 3D temperature maps of water streams or to validate and refine existing models of water temperature fluctuations. This data assists in finding locations of groundwater sources and their contribution to the stream helps to better understand river ecosystems, determine the distribution of studied species and their migration paths.

Other fields that utilize distributed temperature sensors include healthcare and biomedicine fields, fire detection, oil and gas production, detection of leakages, pipelines integrity surveillance, and others.

Optromix company manufactures stainless-steel housed optic sensors that are tensile and impact resistant. If you would like to purchase Optromix FBG Temperature Sensors, please contact us: info@optromix.com or +1 617 558 98 58.