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Fiber Bragg grating sensor for measurement of impact absorption capability of mouthguards
No full textThere is no standard technique to monitor impact
absorption capability of mouthguards. Earlier investigations have established that strain transferred to the teeth through mouthguard is a good indication of
their efficiency. In the present study, a unique experimental scheme utilizing fiber Bragg gratings (FBGs) as distributed strain sensors is proposed and investigated
to estimate impact absorption capability of custom-made mouthguard. The proposed methodology is useful due to advantages such as, very small size and flexibility for ease of bonding, self-referencing, and multiplexing capability of using FBG sensors. Material and methods: Finite-element analysis was performed to simulate the stress distribution due to impact on the mouthguard. The
FBGs were fabricated by exposing the core of photosensitive fiber to intense Ultra-Violet light through a ‘phase mask’. One FBG sensor was bonded on the jaw model and another on the mouthguard surface at similar positions, so that
both gratings are simultaneously affected by impact. Two different sets of the sensors were used, one for the anterior region and another for posterior region.
The impact was produced using customized pendulum device with interchangeable impact objects i.e. cricket ball, hockey ball, and steel ball. Response of gratings was monitored using optical spectrum analyzer and strain induced
due to each impact was determined from the Bragg wavelength shifts for each grating. Results and conclusions: Strain induced due to impact was calculated from the Bragg wavelength shifts. Difference in the strain values for the two gratings is interpreted as impact energy absorbed by the mouthguard. The Bragg wavelength shifts (induced strain) for FBG bonded on the jaw model was much
lower than the shift for FBG bonded on the mouthguard, indicating that most of the impact energy is absorbed by the mouthguard
Thermal Imaging And Its Application In Defence Systems
Get PDFThermal imaging is a boon to the armed forces namely army, navy and airforce because of its day night working capability and ability to perform well in all weather conditions. Thermal detectors capture the
infrared radiation emitted by all objects above absolute zero temperature. The temperature variations of the
captured scene are represented as a thermogram. With the advent of infrared detector technology, the bulky cooled
thermal detectors having moving parts and demanding cryogenic temperatures have transformed into small and less
expensive uncooled microbolometers having no moving parts, thereby making systems more rugged requiring less
maintenance. Thermal imaging due to its various advantages has a large number of applications in military and
defence. It is popularly used by the army and navy for border surveillance and law enforcement. It is also used in
ship collision avoidance and guidance systems. In the aviation industry it has greatly mitigated the risks of flying in
low light and night conditions. They are widely used in military aviation to identify, locate and target the enemy
forces. Recently, they are also being incorporated in civil aviation for health monitoring of aircrafts
DNA Bases as Molecular Electronic Devices
No full textThe current voltage characteristics have been obtained for the four DNA bases Adenine, Thymine, Guanine and Cytosine by
non-equilibrium Green‟s function combined with density
functional theory. The pattern of current flow for an applied voltage sweep of 0-5 V is plotted. The phenomenon of
tunneling is exhibited in the characteristics of molecules. The DNA base cytosine displays a typical surge of current in the voltage sweep section of 0.4V-0.6V, indicating single electron effects. The effect of gate voltage on the current-voltage characteristics of cytosine was studied in the gated two-probe setup. The typical section of characteristics of cytosine was re-drawn by varying the gate potential. The application of gate bias exhibits excellent ON/OFF switching for combinations of the two applied voltages- source voltage and gate voltage.
Repetitive peaks are also observed in current when gate
voltage is varied, fixing source potential. In this paper the cytosine molecule is proposed as a switch, AND gate and OR gate in this paper that can be used in DNA based molecular electronic devices
Time‐Frequency Approach for Stochastic Signal Detection
No full textThe detection of events in a stochastic signal has been a subject of great interest. One of the oldest signal processing technique, Fourier Transform of a signal contains information regarding frequency content, but it cannot resolve the exact onset of changes in the frequency, all temporal information is contained in the phase of the transform. On the other hand, Spectrogram is better able to resolve temporal evolution of frequency content, but has a trade‐off in time resolution versus frequency resolution in accordance with the uncertainty principle. Therefore, time‐frequency representations are considered for energetic characterisation of the non‐stationary signals. Wigner Ville Distribution (WVD) is the most prominent quadratic time‐frequency signal representation and used for analysing frequency variations in signals.WVD allows for instantaneous frequency estimation at each data point, for a typical temporal resolution of fractions of a second. This paper through simulations describes the way time frequency models are applied for the detection of event in a stochastic signal
In-Situ Direct Electrochemistry of Hemoglobin Using Vertically Aligned Carbon Nanotube Ropes
No full textDirect electrochemistry of hemoglobin (Hb) is usually implemented by immobilizing it on the electrode. In-situ determination of Hemoglobin is little bit tough due to slow electron transfer in solution phase owing to its complex structure. In this study, we report in-situ direct electrochemistry of hemoglobin using vertically aligned single walled carbon nanotubes (SWNTs) ropes on indium tin oxide (ITO) platform. Morphological characterization of aligned SWNTs is accomplished using optical surface profiler, FE-SEM and AFM. Electrochemical impedance spectroscopy (EIS) of SWNT/ITO electrode reveals reduction in 'charge transfer resistance' for SWNT/ITO electrode in comparison to ITO. Exchange current density increases tenfold (5.4 × 10-2 A cm-2 while standard rate constant increases hundred times (1.2 × 10-4 C2s-1 cm-2 after vertical alignment of SWNTs on ITO sur- face. Cyclic voltammetry (CV) of Hb demonstrates tenfold increase in the currents after SWNT immobilization. Kinetic studies using CV revel surface controlled nature of the reaction that is attributed to concentration of Hb molecules in close proximity of the electrode, which in turn is due to negatively charged carboxyl ends of aligned carbon nanotubes. Moreover, a plausible mechanism for increase of peak currents in acidic pH range is also presented that clearly demonstrates the role of oxygen containing groups at the carbon nanotube ends for direct electron transfer from hemoglobin. Sensitivity of the sensor is determined for both lyophilized Hb and that present in red blood cells (RBCs) separated from whole blood. It is found to be 21.2 μAμM-1 and 8.94 μAdLg-1 respectively. Lower detection limit of hemoglobin is found to be 10 nM. After successful demonstration of aligned carbon nanotubes (CNTs) in solution phase electrochemistry of hemoglobin, SWNT/ITO electrodes can be used for routine clinical determination of hemoglobin in whole blood samples using RBCs
Exoskeleton Device for Rehabilitation of Stroke Patients Using SEMG during Isometric Contraction
No full textRobots are becoming more interactive and assisting to human beings day by day. They are serving humanity in the fields of industry, defense and medicine. Exoskeletons are also devices that reside in category of wearable robotics. An exoskeleton is an external structural mechanism with joints and links corresponding to those of the human body. With applications in rehabilitation medicine and virtual reality simulation, exoskeletons offer benefits for both disabled and healthy populations. Exoskeletons can be used as a capability magnifier or assisting device. This paper presents a proposed design for smart active exoskeleton for lower limbs. This proposed exoskeleton design not only assist a person but also tries to improve its GAIT. The twin wearable legs are powered by Actuators, all controlled by a microprocessor. The simulation results of the control mechanism shows its smart capabilities. In addition, the processor based control produces a more natural muscle like activity and as such can be considered a soft and bio-mimetic actuation system. This capacity to “replicate” the function of natural muscle and inherent safety is extremely important when working in close proximity to humans. The integration of the components sections and testing of the performance will also be considered to show how the structure and actuators can be combined to produce the various systems needed for a highly flexible/low weight clinically viable rehabilitation exoskeleton
Fabrication of Langmuir-Blodgett film from Polyvinylpyrrolidone stabilized NiCo alloy nanoparticles
No full textThe fabrication of monolayer/multilayer films of Polyvinylpyrrolidone (PVP) stabilized NiCo alloy nanoparticles with an average particle size 7 nm via Langmuir–Blodgett method is presented in this paper. The NiCo alloy nanoparticles were synthesized in ethanol using hydrazine hydrate as reducing agent at 60 °C in the presence of PVP and washed with a mixture of chloroform–methanol (1:1) solution to get pure PVP capped alloy nanoparticles. The NiCo alloy suspension was spread to the interface of air/water and transferred to the glass surface. The formation of a Langmuir monolayer/multilayer of PVP stabilized NiCo particles at air/water interface were revealed with the pressure-area isotherm curve. The transfer of nanoparticles on the glass surface was found to be efficient for the first six layers as exhibited by the pressure-area isotherm and increases in absorption intensity in the UV–Vis range. The atomic force microscopy results show that this film has a cubic symmetry in a two dimensional (2D) array.
Manish Kumara, Anjali Pathaka, Mandeep Singhb, M.L. Singlaa
Fiber Bragg grating sensor for monitoring bone decalcification
No full textEstimation of decalcification is a vital tool to discern bone health. Different techniques are used for its quantitative measurement, e.g. DEXA, QCT & QUS. All these techniques, although noninvasive, suffer from limitations such as radiation exposure and inaccurate values. Recently, fiber optic techniques are fast emerging for medical applications owing to their various attractive features like immunity to EMI/RFI, geometric versatility, chemical inertness, etc.by V Mishra, N Singh, D V Rai, U Tiwari, G C Poddar, S C Jain, S K Mondal, P Kapu
A Novel iTongue For Indian Black Tea Discrimination
No full textA novel impedance-Tongue (iTongue) based on multi-electrode Electrochemical Impedance Spectroscopy is proposed for discrimination of Indian black tea. Impedance response of platinum, gold, silver, glassy carbon, polyaniline and polypyrrole working electrodes in tea infusions for a sinusoidal excitation in the frequency range of 1 Hz to 100 kHz has been measured. Also, the percentage of major chemical constituents responsible for the tea quality has been determined by HPLC and UV–vis spectrophotometer. Frequency specific impedance response of these working electrodes along with the determined chemical concentrations was subjected to Principal Component Analysis to confirm the discriminability of the proposed iTongue. The correlations between the frequency specific impedance response of working electrodes and the chemical concentrations which depend on sample variability, such as harvest interval, manufacturing process and brand type have been established. These correlations were further used for dimensionality reduction and discriminability enhancement. The results show that the frequency specific responses of working electrodes play a key role in discrimination of Indian black tea which can be enhanced by combination of working electrodes and their frequency specific responses.
; ; SHARMA ; BHAKTA ; GANGULI Abhijit ; BARI S. S. ; VIG ; KAPUR Pawan ; SINGLA Madan L.