Fiber Optic Sensors for Vital Signs Monitoring. A Review of Its Practicality in the Health Field

Abstract

Vital signs not only reflect essential functions of the human body but also symptoms of a more serious problem within the anatomy; they are well used for physical monitoring, caloric expenditure, and performance before a possible symptom of a massive failure—a great variety of possibilities that together form a first line of basic diagnosis and follow-up on the health and general condition of a person. This review includes a brief theory about fiber optic sensors’ operation and summarizes many research works carried out with them in which their operation and effectiveness are promoted to register some vital sign(s) as a possibility for their use in the medical, health care, and life support fields. The review presents methods and techniques to improve sensitivity in monitoring vital signs, such as the use of doping agents or coatings for optical fiber (OF) that provide stability and resistance to the external factors from which they must be protected in in vivo situations. It has been observed that most of these sensors work with single-mode optical fibers (SMF) in a spectral range of 1550 nm, while only some work in the visible spectrum (Vis); the vast majority, operate through fiber Bragg gratings (FBG), long-period fiber gratings (LPFG), and interferometers. These sensors have brought great advances to the measurement of vital signs, especially with regard to respiratory rate; however, many express the possibility of monitoring other vital signs through mathematical calculations, algorithms, or auxiliary devices. Their advantages due to miniaturization, immunity to electromagnetic interference, and the absence of a power source makes them truly desirable for everyday use at all times.

Recent Advances in Biomedical Photonic Sensors: A Focus on Optical-Fibre-Based Sensing

“…Vital-sign monitoring includes the body’s essential functions such as pulse rate, body temperature, respiration rate, blood pressure, and others. Optical-fibre sensors can improve vital-sign monitoring of the human body [ 2 ]. Miniaturization and immunity to electromagnetic fields are essential characteristics of optical fibres that could enable their use, for instance, in magnetic resonance (MR) interventions and reduce the burden to patients, avoiding bulky measurement systems.…”

“…Miniaturization and immunity to electromagnetic fields are essential characteristics of optical fibres that could enable their use, for instance, in magnetic resonance (MR) interventions and reduce the burden to patients, avoiding bulky measurement systems. Most common sensors are based on FBG, long-period fibre gratings (LPFG), and interferometers (e.g., FPI) [ 2 ]. Regarding fibre type, in general, silica and polymer optical fibres (POF) are commonly used.…”

“…Measurements of movement and heart rate in 20 volunteers were performed employing two sensors located in distinct parts of the bed. Different data processing methods were evaluated, and the optimal processing method exhibited high accuracies (below 3% instantaneous error, comparable to other optical-fibre sensors [ 2 ]) and heart rate mean difference with the reference below 10% beats per minute [ 51 ]. More recently, a comparison of postprocessing data methods for breath and heart-rate sensing was performed on ten volunteers [ 52 ].…”

U-Shaped Optical Fiber Probes Coated with Electrically Doped GQDs for Humidity Measurements

“…Numerous researchers have modified optical fibers to work as sensors and improved their sensitivity and accuracy when measuring physical quantities. Advances in optical fiber technology have increased the range and utility of optical fiber applications [ 4 , 5 ]. Researchers have studied the uses of optical fibers in medicine, defense, and aerospace.…”

Photonic Integrated Interrogator for Monitoring the Patient Condition during MRI Diagnosis

“…An interesting alternative, however, may be offered by optical sensors, and specifically fiber-optic sensing elements like fiber Bragg gratings (FBGs) [ 1 , 2 ]. The investigations shown in [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ] have proved the possibility of detecting heart rate (HR) and respiratory rate (RR) using optical signals reflected from FBGs, exposed to indirect contact with a human body. It has been confirmed that both HR and RR signals can be extracted from changes of the Bragg wavelength, which are the result of changes of the pressure imposed on FBGs by a human body, and which can be recorded using an appropriate interrogating system.…”