Author: John Mulindi
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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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The Applications of Microcontrollers in Medical Instrumentation
A microcontroller is a self-contained device that includes a CPU, ROM, RAM, clock circuity and I/O circuity on a single integrated circuit (IC) package. A microcontroller does not require accompanying support chips for its operation as conventional microprocessors do. A microcontroller often replace analog circuits by performing the signal processing functions of a comparator, limiter,…
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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…
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Key Factors to Consider in the Design and Operation of Electrocardiograph
There are various factors that must be considered in the design and application of the electrocardiograph. These key factors must be considered by the biomedical engineer as well as the electrocardiograph operator and the physician who interprets the recorded information. We discuss these factors as follows: Frequency distortion The electrocardiograph does not always meet the…
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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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Key factors that affect or limit Biomedical Measurements
Low measurement ranges – Biomedical instruments are used to measure various medical and physiological parameters. Most of the parameter measurement ranges are quite low compared with non-medical parameters. For example, most biomedical voltages are in the microvolt range and the pressures are also low about 1.93 psi. These general properties of medical parameters limit the…
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The Essential Requirements of Biopotential Amplifiers for Medical applications
Biopotential amplifiers are also termed to as Bioamplifiers. Bioelectric measurements are normally low-level voltages with high source impedances therefore signal amplification is essential part of biomedical measurement systems. The signal amplification is needed to boost or increase the strength of the input signal to match the requirements of recording/display systems. We have specialized amplifiers designed…
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Key Features of a Disposable Blood Pressure Sensor
Disposable blood pressure sensors are made of clear plastic so that air bubbles are easily seen Saline flows from an intravenous (IV) bag through the clear IV tubing and the sensor to the patient. This is used to flush out blood out of the tip of the indwelling catheter to prevent clotting. A lever can…
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3 Sources of Noise in Biomedical Measurement Systems
Biomedical measurements involve low-level signals which are susceptible to noise interference. We have 3 common sources of noise in biomedical measurements which are: Improper Grounding Grounding means a low impedance metallic connection to a properly designed ground grid, located in the earth. Placing more than one ground on a signal circuit produces a ground loop…