Tag: medical devices
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Principle of Working of a Demand Cardiac Pacemaker
A cardiac pacemaker is normally used to produce pulses that force the heart to beat at higher rate; this is particularly important when blockage occurs to the biological signals that stimulate the heart to beat. A demand pacemaker is specifically helpful to the patient with partial blockage, in which case an electric pulse to the…
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What is Single Photon Emission Tomography (SPECT)?
Single Photon Emission Tomography (SPECT) is a technique for producing 3D images from 2D images of injected radionuclide in the body. The 2D image is obtained by using a device such as a gamma camera. This comprises of a large (0.5 diameter) crystal of NAI, which emits flashes of light when γ-rays impinge on it.…
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The Principle & Applications of Confocal Imaging
Confocal imaging (CI) is based on illuminating a single point on the sample and collecting scattered light from the same point of the sample. The illumination point on the sample is the image of the illumination pinhole and is imaged into the detector pinhole, hence making both pinholes and the illuminated spot on the sample…
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Principle Parts and Types of ECG Recorders
Building Blocks of an ECG System In Electrocardiography (ECG) recorder five leads from the patient are connected to the ECG recorder through a selector switch to obtain 12 lead configurations as illustrated below: A standard voltage of 1 mV is used to calibrate the recorder. The output from the lead selector switch is amplified using…
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What is the Function of a Phonocardiograph?
A phonocardiogram is a recording of the heart sounds and murmurs. The instrument used to make this recording is called the phonocardiograph. The recording of all the heart sounds during a cardiac cycle is termed to as phonocardiography. Phonocardiogram eliminates the subjective interpretation of the heart sounds and makes it possible to evaluate them with…
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How Liquid Crystal Sensors are used in Biomedical Measurements
The principle of operation of liquid crystal sensors is based on the fact that liquid crystals change their state in such way that they modify passive scattering or absorption of light. As the crystal melt, the three-dimensional order becomes a two-dimensional or one dimensional order, layers or strands form that can be seen as a…