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Gait analysis is vital from the view of its established capacity as an indicator for neuromuscular disorders. Gait analysis is carried out in order to provide a quantified assessment of human movement which may aid orthopaedic and podiatric fraternity to suggest suitable therapeutic treatment. The proposed study comprises of two wearable non-invasive devices realized using FBG sensors i.e. Knee Angle Measurement Device (KAMD) for dynamic knee angle measurement and Forefoot Load Measurement Device (FLMD) for dynamic measurement of load on the forefoot. In the present study, the assessment of locomotion is illustrated and analyzed utilizing the developed devices without any time synchronization complexity. During locomotion, the swing and the stance phase is analyzed with respect to both knee joint angle and forefoot load which further reveals the complementary nature between them. In addition, FLMD can also be utilized for the evaluation of single and double limb support phases during locomotion. Furthermore, the novel cantilever approach utilized in the FLMD design ensures to acquire the load imparted specifically over the forefoot region which facilitates FLMD to be employed for assessment of other locomotory actions such as landing phase analysis during leaps, climbing stairs, treadmill tests etc. Also, the cantilever approach helps minimize the hysteresis effects on the device.

Finger plethysmography is a well-known technique for the acquisition of arterial pulse waveforms in the field of cardiology. The technique involves the acquisition of the volumetric variation of the finger due to pulsatile flow of blood in ulnar artery, to obtain the arterial pulse waveform of the subject. Conventionally, finger plethysmography is carried out by pulse-oximetry method which evaluates the blood flow using the oxygen saturation levels in blood. Though this method is widely used, the data acquired from this method is not the actual pulse pressure experienced by the arterial walls. Therefore, in the present work, a novel, non-invasive Fiber Bragg Grating based arterial pulse acquisition device employing finger Plethysmographic technique is designed and developed. The developed Fiber Bragg Grating Plethysmographic Pulse Recorder (FBGPPR) can acquire the volumetric variations of the finger on a beat-to-beat basis, which represents the arterial pulse waveform. Further, Pulse Transit Time (PTT) evaluation is also illustrated employing FBGPPR and an electronic stethoscope wherein both the devices are triggered simultaneously. Furthermore, the acquired pulse waveforms are analyzed to obtain the accelerated pulse plethysmograph (APG) which is noteworthy to observe the minute inflections and vital features of the pulse waveform.

Thermal imaging is one of the emerging non-invasive neuro-imaging techniques utilized for demarcation of intra-axial brain tumor borders. Tissue regions comprising of tumors is known to attain higher temperature on the surface due to the increased rate of blood flow and cell metabolism and therefore the variation in tissue surface temperature may be accounted as an indicator of a tumor existence. In the present work, Fiber Bragg Grating based Thermal Sensor (FBGTS) is developed for temperature measurement of a simulated tissue based on Agar material which mimics the soft tissue of brain. A heater is embedded inside the simulated tissue which mimics the tumor’s temperature variation inside the brain. The temperature of the embedded heater along with the surface temperature of the simulated tissue is acquired simultaneously using two FBGTS probes. Further, the temperature variations on the surface of the simulated tissue are studied for varying heater temperatures as well as for the varying position of the heater inside the simulated tissue, indicating varying positions of brain tumors. The present study proposes and demonstrates the feasibility of using FBGTS for thermography from which the possible detection and approximate position of an existing brain tumor can be evaluated.

The present in vitro study proposes a novel (to the best of our knowledge) methodology employing a fiber Bragg grating sensor for the evaluation of pulp chamber temperature increase during the polymerization of the composite resin induced by the light-curing process. A fiber Bragg grating temperature sensor (FBGTS) has been developed in view of its ease of insertion into the pulp chamber with minimal widening of the pulpal canal. The temperature increase in the pulpal chamber during the polymerization of the composite resin by light curing has been characterized with varying depths of cavities of 1 mm, 1.5 mm, and 2 mm employing FBGTS. Also, the increase in temperature of the pulpal chamber during the polymerization of the composite resin has been studied with variants of the light-curing device. The obtained results are expected to be an indicator towards the potential hazard caused by heat induced pulpal injuries during the polymerization of composite resins using a light-curing device.

Human joint kinematics has established its capacity as a vital tool for joint pathology and gait analysis. Range of motion (ROM) of a knee joint performed by flexion and extension is an essential tool to assess the efficacy of surgical interventions or therapeutic assessment. This paper proposes a novel wearable device for dynamic measurement of knee joint angle using fiber Bragg grating (FBG) sensor. The proposed knee angle measurement device (KAMD) can transduce the angular movement between the shin and the thigh into strain variations on a cantilever, which is acquired by the FBG sensor over it. The KAMD is also facilitated with tuneable sensitivity with three modes of high sensitivity mode, medium sensitivity mode, and low sensitivity mode, which can be opted based on application specific resolution and range of measurement. The ROM data obtained from the KAMD are validated against ROM obtained from commercially available Polhemus Sensors. Furthermore, the synchronization of the knee joint movement of both legs during walking along with stance and swing phase is illustrated, which shows the ability of KAMD to perform gait analysis. Employment of KAMDs on both legs eliminating the time synchronization complexity makes the proposed FBG-based KAMD an efficient means to evaluate the knee angle from both legs simultaneously.

Graphical abstract, Highlights • FBGET is novel, non-invasive, and easy to mount eye tracking methodology. • FBGET can be utilized as a point of care device. • FBGs are electrically and chemically inert, hence suitable for biomedical sensing. • FBGET tracks both eyes simultaneously eliminating time synchronization complexity. • FBGET can facilitate diagnosis of ophthalmological/neurological disorders., Eye movement evaluation is vital for diagnosis of various ophthalmological and neurological disorders. The present study proposes a novel, noninvasive, wearable device to acquire the eye movement based on a Fiber Bragg Grating (FBG) Sensor. The proposed Fiber Bragg Grating Eye Tracker (FBGET) can capture the displacement of the eyeball during its movements in the form of strain variations on a cantilever. The muscular displacement generated by the eyeball over the lower eyelid, by its swiveling action while moving the gaze on a target object, is converted into strain variations on a cantilever. The developed FBGET is investigated for dynamic tracking of the eye-gaze movement for various actions of the eye such as fixations, saccades and main sequence. This approach was validated by recording the eye movement using the developed FBGET as well as conventional camera-based eye tracker methodology simultaneously. The experimental results demonstrate the feasibility and the real-time applicability of the proposed FBGET as an eye tracking device. In conclusion, the present study illustrates a novel methodology involving displacement of lower eyelid for eye tracking application along with the employment of FBG sensors to carry out the same. The proposed FBGET can be utilized in both clinical and hospital environment for diagnostic purposes owing to its advantages of wear-ability and ease of implementation making it a point of care device.

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.

Goniometers are extensively used in the medical field, in order to assess the range of angular motion of a joint, especially for therapeutic assessment during physiotherapy. This paper reports a novel device for the dynamic measurement of angular motion of joints using a fiber Bragg grating (FBG) senor. The fiber Bragg grating goniometer (FBGG) is proposed, essentially converts the rotational motion of a joint into strain variation on a cantilever, which is acquired by the FBG sensor bonded over it. The FBGG developed has the capability of measuring joint angles in the range of 0°–200° with a resolution of 0.06°. The FBGG developed has been put to use in the measurement of angular motion of elbow joint along with ankle joint. The angular measurements obtained from the FBGG are validated against the angular measurements from the Polhemus liberty sensor. It is observed that the angular motions acquired from both the methodologies are in good agreement with each other, which proves the usefulness of the FBGG developed. Also, with the inherent advantages of the FBG sensor, the FBGG developed provides an efficient means of evaluation of angular motion of joint, which may be utilized as a platform sensor methodology for angular measurement of various other joints in the human body.

Pulmonary function tests (PFTs) are noninvasive diagnostic tests that evaluate the functionality of the lungs. Spirometry is an established diagnostic tool for the evaluation and management of lung disorders. Pulmonary function testing carried out using a spirometer provides vital information about the functional status of the respiratory system. In this study, a spirometer based on a fiber Bragg grating (FBG) sensor for PFT has been proposed. The proposed fiber Bragg grating spirometer (FBGS) is a novel, noninvasive device that has the ability to convert the rate of air flow into strain variations using an FBG sensor bonded on a cantilever. The FBGS dynamically acquires in real time, the complete breath sequence comprising of inhalation phase, pause phase, and exhalation phase, in terms of the air flow rate along with the time duration of each phase. Fundamental pulmonary parameters such as forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), the FEV1/FVC ratio, and peak expiratory flow are evaluated from the data obtained from the FBGS, which will aid greatly during clinical tests. The results from the FBGS developed are compared with a standard hospital grade pneumotachograph-based spirometer for a sample size of 16 subjects to prove the efficacy of the proposed device.

Tactile sensation is one of the most important sensory inputs extensively used by the humans for their perception. It is an important parameter for diverse biomedical and industrial applications involving robotic system intervention. The present study proposes design and development of a real time dynamic haptic force monitoring system for human grasping of various objects employing Fiber Bragg Grating sensor. The dynamic force variation on the index finger during grasping of an object with minimum force application is determined by the Fiber Bragg Grating based Haptic Device (FBGHD). The FBGHD comprises of a wearable glove provided with a base plate fixed on the distal phalanx of the index finger and a tactile plate, where both the plates are held together by supporting cylindrical beams. When an object is grasped wearing the glove, the supporting beam experiences a compressive strain which is an indicator of the haptic grasp force. The induced strain is sensed and monitored by fiber Bragg grating sensor bonded over the surface of the beam. Two categories of experiments for estimating effective haptic grasp force are conducted on incremental weights and further on random objects with varying weights, dimensions and texture. FBGHD acts a sensing element for a robotic system for haptic sensing of force application on an object grasp, that can be extensively utilized during robotic based healthcare or industrial application.

Arterial pulse is an established source of information for the clinical assessment of cardiovascular health. The central aortic pressure is known to be a better predictor of cardiovascular status than the peripheral pressure. The carotid arterial pulse is considered to be the best indicator of the central aortic pressure. The present work deals with the development of a novel noninvasive probe based on fiber Bragg grating (FBG) sensor for the real-time acquisition of the pulse waveform in the carotid arterial site. The fiber Bragg grating pulse probe (FBGPP) developed is used to obtain the carotid arterial pulse waveform (CAPW) of individual subjects, in the form of beat-to-beat carotid pulse. The FBGPP developed comprises of an elastic rubber diaphragm that comes into contact with the skin below, which the carotid artery is pulsating, creating strain variations over it. Effectively, the carotid arterial pulse is tranduced into the strain variations over a rubber diaphragm, which is acquired by the FBG sensor bonded over it. The FBGPP is designed such that the positioning and the access for the device to the carotid arterial site can be carried out with ease. Furthermore, the recorded CAPW is subjected to the pulse wave analysis in order to evaluate vital cardiovascular parameters like heart rate, left ventricular ejection time, carotid augmentation index, and ejection duration index, which are indicators of the cardiac health of the subject and the performance of the heart. Also, the linearity between these cardiovascular parameters is explored for a sample size of 55.

Landslides are natural hazards which are known to cause loss of life and infrastructural damage. Landslide Early Warning System (LEWS) is intended to predict the occurrence of the landslide which provides ample time to initiate necessary protective measures. In the present study, a Fiber Bragg Grating (FBG) sensor based vibration sensor which can acquire the seismic vibrations is proposed as an LEWS. The proposed Fiber Bragg Grating Vibration Sensor (FBGVS) works on a specially designed cantilever structure, through which the seismic vibrations can be obtained in the form of strain variations on the cantilever. The strain variations over the cantilever will be acquired by the FBG sensor bonded over it. The cantilever is specially designed such that the strain sensitivity of the FBGVS is enhanced, by the appending of torsional strain along with the axial strain. Experimental trials have been carried out which prove the efficacy of the FBGVS to acquire the seismic vibrations. FBGVS acts as the sensing element for an IoT system to ensure the landslide warning signal is transmitted to all remote locations, effectively making an efficient LEWS.

We demonstrate a simple and computationally efficient method to recover the shear modulus pertaining to the focal volume of an ultrasound transducer from the measured vibro-acoustic spectral peaks. A model that explains the transport of local deformation information with the acoustic wave acting as a carrier is put forth. It is also shown that the peaks correspond to the natural frequencies of vibration of the focal volume, which may be readily computed by solving an eigenvalue problem associated with the vibrating region. Having measured the first natural frequency with a fibre Bragg grating sensor, and armed with an expedient means of computing the same, we demonstrate a simple procedure, based on the method of bisection, to recover the average shear modulus of the object in the ultrasound focal volume. We demonstrate this recovery for four homogeneous agarose slabs of different stiffness and verify the accuracy of the recovery using independent rheometer-based measurements. Extension of the method to anisotropic samples through the measurement of a more complete set of resonant modes and the recovery of an elasticity tensor distribution, as is done in resonant ultrasound spectroscopy, is suggested.

The present study proposes a novel real time dynamic pressure sensing device employing Fiber Bragg Grating (FBG) sensor. A hermetically sealed chamber with one surface comprising of a glass epoxy diaphragm is utilized for the differential pressure sensing. The pressure outside the chamber is maintained at atmospheric pressure. Any variation in the pressure inside the chamber will create a pressure differential across the diaphragm, which will in turn create strain variations on the glass epoxy diaphragm. These variations in strain are acquired by the FBG sensor bonded over it. Further, different thicknesses of diaphragms can be tested for pressure sensing, which will react to the change in pressure with different sensitivities. The developed relative pressure sensor is validated against commercial pressure gauge.

Brachial Augmentation Index (BAI) is a known indicator of brachial arterial stiffness. BAI depends on the speed of travel of the blood pressure wave during a cardiac cycle, which is decided by the elasticity of the brachial artery. Evaluation of BAI is necessary as a part of cardiovascular diagnosis, in view of its established capability to forecast cardiovascular diseases. The present study proposes a novel non invasive beat-to-beat brachial arterial pulse pressure waveform (BAPPW) evaluation methodology using Fiber Bragg Grating Sensor. Fiber Bragg Grating Pulse Recorder (FBGPR) is employed to acquire the BAPPW, which has the ability to transduce the pressure in the pulsating brachial artery into strain variations on a silicone diaphragm. The recorded BAPPW is analyzed to obtain the diastolic pressure and systolic pressure indicated by the lowest and the peak point of the BAPPW respectively. The late systolic pressure also known as the augmented pressure is the reflected wave from the peripheral points. The ratio of the late systolic pressure to the systolic pressure is defined as the BAI, which may be evaluated beat-to-beat using FBGPR. The present work is a feasibility study of effective employment of FBGPR for obtaining the BAPPW along with the evaluation of the BAI and heart rate.

The present study reports an in vivo, novel methodology for the dynamic measurement of the bite force generated by individual tooth using a Fiber Bragg Grating Bite Force Recorder (FBGBFR). Bite force is considered as one of the major indicators of the functional state of the masticatory system, which is dependent on the craniomandibular structure comprising functional components such as muscles of mastication, joints and teeth. The proposed FBGBFR is an intra-oral device, developed for the transduction of the bite force exerted at the occlusal surface, into strain variations on a base plate, which in turn is sensed by the FBG sensor bonded over it. The FBGBFR is calibrated against a Micro Universal Testing Machine (UTM) for 0-900 N range and the resolution of the developed FBGBFR is found to be 0.54 N. 36 volunteers (20 males and 16 females) performed the bite force measurement test at molar, premolar and incisor tooth on either side of the dental arch and the obtained results show clinically relevant bite forces varying from 176 N to 635 N. The bite forces obtained from the current study for a substantial sample size, show that the bite forces increases along the dental arch from the incisors towards the molars and are found to be higher in male than in female. The FBG sensor element utilized in FBGBFR is electrically passive, which makes it a safe in vivo intra-oral device. Hence the FBGBFR is viable to be employed in clinical studies on biomechanics of oral function. (C) 2016 Elsevier Ltd. All rights reserved.

Goniometer has found extensive usage in diverse applications, primary being medical field in which it is employed for obtaining the range of motion of joints during physical therapy. It is imperative to have a dynamic system to measure the range of motion which will aid for a progressive therapeutic treatment. Hence in the present study, a novel goniometer for real time dynamic angle measurement between two surfaces with the aid of a Fiber Bragg Grating sensor is proposed. The angular rotation between the two surfaces will be identified by the two arms of the Fiber Bragg Grating Goniometer (FBGG), which is translated to the rotation of the shaft which holds these arms together. A cantilever beam is fixed onto the base plate whose free end is connected to the rotating shaft. The rotating shaft will actuate a mechanism which will pull the free end of the cantilever resulting in strain variation over the cantilever beam. The strain variation on the cantilever beam is measured by the Fiber Bragg Grating sensor bonded over it. Further, the proposed FBGG facilitates tunable sensitivity by the discs of varying diameters on the rotating shaft. Tunable sensitivity of the FBGG is realised by the movement of these discs by varying circumferential arc lengths for the same angular movement, which will actuate the pull on the cantilever beam. As per the requirement of the application in terms of resolution and range of angular measurement, individual mode of sensitivity may be selected.

Improvements in emergency medicine in the form of efficient life supporting systems and intensive care have increased the survival rate in critically injured patients; however, in some cases, severe brain and spinal cord injuries can result in a locked-in syndrome or other forms of paralysis, and communication with these patients may become restricted or impossible. The present study proposes a noninvasive, real-time communication assistive methodology for those with restricted communication ability, employing a fiber Bragg grating (FBG) sensor. The communication assistive methodology comprises a breath pattern analyzer using an FBG sensor, which acquires the exhalation force that is converted into strain variations on a cantilever. The FBG breath pattern analyzer along with specific breath patterns, which are programmed to give specific audio output commands, constitutes the proposed fiber Bragg grating sensor-based communication assistive device. The basic communication can be carried out by instructing the patients with restricted communication ability to perform the specific breath patterns. The present approach is intended to be an alternative to the common approach of brain-computer interface in which an instrument is utilized for learning of brain responses. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)

Fiber Bragg Grating (FBG) sensors have become one of the most widely used sensors in the recent times for a variety of applications in the fields of aerospace, civil, automotive, etc. It has been recently realized that FBG based accelerometer's performance meets and/or exceeds that of traditional sensors. The present work is about the development of a novel, real-time, dynamic two dimensional Accelerometer employing FBG sensors. The proposed FBG Accelerometer works on the principle of inertial mass acceleration which in turn produces strain variations on the adjoining cantilevers, obtained using the FBG sensors bonded over it. The proposed device facilitates compact size and low fabricating cost along with the inherent advantages of FBG sensor, making it an effective device for measuring acceleration.

Hand tremor is an involuntary muscle movement, trembling, or shaking of the hands. Tremor most accurately refers to a small, rhythmic shaking movement that occurs in oscillatory pattern. Frequency amplitude analysis of the hand tremor can be an indicator of the subject being prone to Parkinson's disease. Parkinsonian tremors typically have a frequency of 4–6Hz when the hand is at rest. In this regard, a novel in-vivo dynamic Fiber Bragg Grating Tremor Measurement (FBGTM) device is developed based on a cantilever vibration method. The strain variations due to the hand tremors, created over the cantilever are acquired by the Fiber Bragg Grating sensor bonded over it. Frequency analysis of the recorded data will be an indicator towards the probability of the subject being prone to Parkinson's disease. The use of Fiber Bragg grating sensors brings potential advantages, such as insensitivity to electromagnetic interference, low fatigue, and ultra-fast response, making the proposed hand tremor measurement device an effective means for the evaluation of hand tremors in subjects.

Non-invasive, real-time dynamic monitoring of pressure inside a column with the aid of Fiber Bragg Grating (FBG) sensor is presented in the present work. A bare FBG sensor is adhered on the circumference of a pressure column normal to its axis, which has the ability to acquire the hoop strain induced by the pressure variation inside the column. Pressure induced hoop strain response obtained using FBG sensor is validated against the pressure measurements obtained from conventional pressure gauge. Further, a protrusion setup on the outer surface of the column has been proposed over which a secondary FBG sensor is bonded normal to its axis, in order to increase the gauge length of this FBG sensor. This is carried out in order to validate the variation in sensitivity of the protrusion bonded FBG sensor compared to the bare FBG sensor bonded over the surface. A comparative study is done between the two FBG sensors and a conventional pressure gauge in order to establish the capacity of FBG sensor obtained hoop strain response for pressure monitoring inside the column.

The maximum level of voluntary bite force, which results from the combined action of muscle of mastication, joints, and teeth, i.e., craniomandibular structure, is considered as one of the major indicators for the functional state of the masticatory system. Measurement of voluntary bite force provides useful data for the jaw muscle function and activity along with assessment of prosthetics. This study proposes an in vivo methodology for the dynamic measurement of bite force employing a fiber Bragg grating (FBG) sensor known as bite force measurement device (BFMD). The BFMD developed is a noninvasive intraoral device, which transduces the bite force exerted at the occlusal surface into strain variations on a metal plate. These strain variations are acquired by the FBG sensor bonded over it. The BFMD developed facilitates adjustment of the distance between the biting platform, which is essential to capture the maximum voluntary bite force at three different positions of teeth, namely incisor, premolar, and molar sites. The clinically relevant bite forces are measured at incisor, molar, and premolar position and have been compared against each other. Furthermore, the bite forces measured with all subjects are segregated according to gender and also compared against each other.

In this paper, we propose a novel methodology of real time dynamic tilt monitoring through the designed and developed Fiber Bragg Grating Tilt Meter (FBGTM). Based on the volumetric water pressure exerted from inside the chamber on the diaphragm over which the FBG sensor is bonded, the tilt angle of FBGTM can be estimated. An inclination platform is constructed to test the designed FBGTM in conjunction with a commercial inclinometer. The results obtained from both sensor methodologies are in good agreement with each other.

A technique for real-time dynamic monitoring of force experienced by a spinal needle during lumbar puncture using a fiber Bragg grating (FBG) sensor is presented. The proposed FBG force device (FBGFD) evaluates the compressive force on the spinal needle during lumbar puncture, particularly avoiding the bending effect on the needle. The working principle of the FBGFD is based on transduction of force experienced by the spinal needle into strain variations monitored by the FBG sensor. FBGFD facilitates external mounting of a spinal needle for its smooth insertion during lumbar puncture without any intervention. The developed FBGFD assists study and analysis of the force required for the spinal needle to penetrate various tissue layers from skin to the epidural space; this force is indicative of the varied resistance offered by different tissue layers for the spinal needle traversal. Calibration of FBGFD is performed on a micro-universal testing machine for 0 to 20 N range with an obtained resolution of 0.021 N. The experimental trials using spinal needles mounted on FBGFD are carried out on a human cadaver specimen with punctures made in the lumbar region from different directions. Distinct forces are recorded when the needle encounters skin, muscle tissue, and a bone in its traversing path. Real-time spinal needle force monitoring using FBGFD may reduce potentially serious complications during the lumbar puncture, such as overpuncturing of tissue regions, by impeding the spinal needle insertion at epidural space. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)