Tag: Biomedical Instrumentation
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The General Principle of Fiber Optic-based Sensor
Optical sensors are typically interfaced with an optical unit. This optical component supplies the excitation light, which may be from a monochromatic source such as a diode laser or from a broadband source e.g. quartz-halogen that is filtered to provide a narrow bandwidth of excitation. Typically, two wavelengths of light are employed: one that is…
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Key Features of ECG Amplifiers
A differential amplifier is employed as ECG amplifier instead of the typical electronic amplifiers. The reason why the electronic amplifiers aren’t employed in electrocardiograph (ECG) is because they create an interference problem when they are used to measure small bioelectric potentials. A differential amplifier can be considered as two amplifiers having separate inputs but they…
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Functions & Types of Pneumotachometers for Biomedical Measurements
Pneumotachometers are instruments that measure the instantaneous rate of volume flow of respired gases. They can be broadly classified into two types based on the principle of operation: The pneumotachometer is normally used to measure parameters relating to pulmonary function such as forced expiratory volume (FEV), maximum mid-expiratory volume, & peak flow and to generate…
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The Functions of Signal Conditioners in Biomedical Measurement Systems
In a Biomedical measurement system, the electrodes pick up the bioelectrical potential whereas the transducer converts the physiological signal to be measured into a usable electrical output. The outputs from the Bioelectrodes/transducers are then converted into an electrical quantity that is suitable for operating a display or recording device with the help of a signal…
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Key Factors to Consider when Designing Biomedical Instruments
Some of the important factors that are considered when designing a medical measuring instrument include:
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Blood Pressure Measurement
Introduction The blood pressure is considered a good indicator of the status of the cardiovascular system. The blood pressure can be measured by: Indirect methods of Blood Pressure Measurement Examples of indirect methods of blood pressure measurement include: Sphygmomanometer In this method the occlusive cuff is inflated until the pressure exerted by the cuff on…
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Blood Flow Measurement
Introduction Blood flow can easily be measured by using biomedical instruments. These biomedical instruments are based on several working principles namely: The magnetic and ultrasound blood flow meters actually measure the velocity of the blood stream. A transducer is used that envelope an excised blood vessel to measure the mean velocity of the blood stream.…
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A Basic Biomedical Recording System
Recorders provide permanent visual trace or record of an applied electrical signal. The most basic electronic recording system consists of 3 important components: The electrode picks up the bioelectric potentials whereas the transducer converts the physiological signal to be measured into a usable electrical output. The signal conditioner converts the output of the electrode/transducer into…
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Types of Bioelectrodes
Introduction Bioelectric events have to be picked up from the surface of the body before they can be put to the amplifier for subsequent record or display. This is done by use of electrodes. The potentials produced at different points are measured by placing electrodes at various points on the body. They carry the currents…
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Sources of Biomedical Signals
Biomedical signals/physiological signals are those signals (phenomenon that conveys information) which are used primarily for extracting information on a biological system under investigation. Our body produces various physiological signals. The accessibility to these signals is important because these signals: All physiological signals can grouped as: A transducer converts a physical signal into an electrical output.…