In this paper we present the results of research aimed at the development of a 'smart' bed to non-intrusively monitor patient respiration, heart rate and movement using spatially distributed integrating multimode fibre optic sensors. The research is focused upon allowing more automation of patient care, an especially important matter for the elder population, which is a rapidly growing fraction of much of the world population today. Two spatially integrating fibre optic sensors were investigated, one of which was based on inter-modal interference and the other on mode conversion. The sensing fibre was integrated into a bed and test subjects were monitored in different positions. The sensor outputs were then correlated with subject movement, respiration rate and heart rate. The results indicated that the inter-modal sensor could detect patient movement and respiration rate while the mode conversion sensor could detect patient movement, respiration rate and heart rate. Results and analysis of the research are presented and future research activities discussed.
Flexible, elastomeric, and superparamagnetic substrates were prepared by electrospinning a solution of elastomeric polyurethane containing ferrite nanoparticles (ϳ14 nm) of Mn-Zn-Ni. The flexible mats were characterized in terms of fiber morphology and magnetic properties. Field emission scanning electron microscopy (FESEM) indicated that the diameter of these composite fibers was ϳ300 -500 nm. Furthermore, the back-scattered electron FESEM images indicated agglomeration of the nanoparticles at higher wt % (ca. 17-26 wt %) loading in the electrospun fibers. The induced specific magnetic saturation and the relative permeability were found to increase linearly with increasing wt % loading of the ferrite nanoparticles on the submicron electrospun fibers. A specific magnetic saturation of 1.7-6.3 emu/g at ambient conditions indicated superparamagnetic behavior of these composite electrospun substrates.
The theory and performance of a two beam differential interferometer for measurement of both surface and bulk waves are described. The system is insensitive to small errors (<1 mm) in focus or in specimen flatness. Both amplitude and phase measurements are demonstrated. The system has been absolutely calibrated and can detect 6 x 10(-4)-A surface wave displacements on glass.
Flexible field responsive superparamagnetic substrates were prepared by electrospinning a solution of elastomeric polyurethane containing ferrite nanoparticles (ca. 14 nm) of Mn-Zn-Ni. The flexible mats were characterized in terms of fiber morphology and magnetic properties. Field Emission Scanning Electron Microscopy (FESEM) indicated that the diameter of these composite fibers was ca. 300-500 nm. Furthermore, the back-scattered electron FESEM images indicated agglomeration of the nanoparticles at higher wt% (ca 17-26 wt%) loading in the electrospun fibers. The induced specific magnetic saturation and the relative permeability were found to increase linearly with increasing wt% loading of the ferrite nanoparticles on the submicron electrospun fibers. A specific magnetic saturation of 1.7 -6.3 emu/g at ambient conditions indicated superparamagnetic behavior of these composite electrospun substrates. Additionally, dielectric constant values of the electrospun fibers were measured to be between 2.3 and 5.8.
This paper presents a recently developed composite constructed in an attempt to improve damping properties by using ferroelectric inclusions in a constrained medium. Several samples of this new composite have been made and tests of their damping properties are presented here. Damping properties of materials are of great interest in many applications. The focus here is on the development of composites with ferroelastic components to develop a new class of materials having improved temperature-dependent damping properties. Typical damping materials, such as viscoelastic materials, have damping values that decrease with increasing temperature. The work presented here considers a material system consisting of fine particles of vanadium dioxide (VO2) and zinc oxide (ZnO) incorporated into matrix materials (tin and polymer adhesives) to produce composite materials with improved damping properties. A number of mechanical damping tests have been conducted on the prepared composites at a frequency range of 0-2000 Hz and over a broad temperature range using piezoceramic exciters and miniature accelerometers. The mechanical vibration test results show that VO2 and ZnO give significantly higher damping values at ≈68° C (155° F) and 29° C (85° F). For example, ≈15 and 12% damping is achieved at the first and second resonance frequencies, respectively. This significant improvement on the damping of the composite materials may be because of the ferroelasticity and/or viscoelasticity at those particular temperatures. It has also been observed that etching of substrate surfaces improves the adhesion between composite materials and surfaces for better damping results. These composites offer high damping at elevated temperatures and hence may provide useful solutions to applications requiring increased damping.
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