Browsing by Author "Sreedevi, V"

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    Design of Electromagnetic Probe Having Reduced Base Line Drift for Blood Flow Measurement
    (IETE JOURNAL OF RESEARCH, 2015) Nair, SS; Vinodkumar, V; Sreedevi, V; Nagesh, DS
    An improved design for electromagnetic probe for blood flow measurement is presented. The probe produces a magnetic field in the column of blood to induce a voltage as per Faraday's laws. The mechanical and electromagnetic structures are designed to reduce the effect of base line drift and signal variations with time which are very common in electromagnetic flow measurement systems. A signal with very less noise and drift is induced with a sensitivity of more than 80 mV/lpm. The signal has a linear variation with flow rates and need no frequent calibration. Signal variations with time are negligible and had less power signal interferences and noisy spikes.
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    Rotating permanent magnet excitation for blood flow measurement
    (MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING, 2015) Nair, SS; Vinodkumar, V; Sreedevi, V; Nagesh, DS
    A compact, portable and improved blood flow measurement system for an extracorporeal circuit having a rotating permanent magnetic excitation scheme is described in this paper. The system consists of a set of permanent magnets rotating near blood or any conductive fluid to create high-intensity alternating magnetic field in it and inducing a sinusoidal varying voltage across the column of fluid. The induced voltage signal is acquired, conditioned and processed to determine its flow rate. Performance analysis shows that a sensitivity of more than 250 mV/lpm can be obtained, which is more than five times higher than conventional flow measurement systems. Choice of rotating permanent magnet instead of an electromagnetic core generates alternate magnetic field of smooth sinusoidal nature which in turn reduces switching and interference noises. These results in reduction in complex electronic circuitry required for processing the signal to a great extent and enable the flow measuring device to be much less costlier, portable and light weight. The signal remains steady even with changes in environmental conditions and has an accuracy of greater than 95 %. This paper also describes the construction details of the prototype, the factors affecting sensitivity and detailed performance analysis at various operating conditions.