Author: John Mulindi
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The Principle of Surface Plasmon Resonance Sensors for Detection of Antibody & Antigen Interactions
When monochromatic polarized light for instance, from a laser source impinges on a transparent medium having a conducting metallized surface (e.g. Ag or Au), there is a charge density oscillation at the interface. When a light at an appropriate wavelength interacts with the dielectric-metal interface at a defined angle, called the resonance angle, there is…
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Key Properties of Bioelectrodes
To record biopotentials, an interface is required between the electron-conducting copper wires connected to signal conditioning amplifiers and the ion-conducting environment of living organisms. Electrodes form this interface. Some of the several kinds of electrodes are better than others in terms of low noise and ease of use. Initial ECG electrodes were non-disposable, nickel-silver plated…
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The Principle of Temporal Artery Thermometer
This is a non-invasive scanning thermometer for measuring core body temperature. The measurement is based on scanning the area above the temporal artery using an IR detector. The superficial temporal artery extends directly from the external carotid artery and travels in front of the ear. Anatomically, it is lying approximately 1 mm below the skin,…
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Basic Features of Enzyme Based Biosensors
Enzymes are the commonly used biological sensing element in the fabrication of various biosensors. Enzymes have unique properties and ability to accelerate chemical reactions inside biological cells. Most enzymes react only with specific substrates even though they may be contained in a complicated mixture with other substances. However, it is imperative to keep in mind,…
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Fleisch Pneumotachometer Operation & Biomedical Application
Fleisch Pneumotachometer is one of the most common types of airflow transducers. It consists of a straight short-tube with a fixed screen obstruction in the middle that produces a slight pressure drop as the air is passed through the tube. The pressure drop created across the screen is measured by a differential pressure transducer. The…
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The Function of a PET scan in Biomedical Diagnostics
The radionuclides that are employed in a PET scan as part of radiopharmaceuticals work best when used for imaging certain physiological properties. Combined with a CT scan or an MRI, a PET scan is good for locating things such as tumours. As a matter of fact, a PET scan can light up for the brain,…
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Key Features of EMG Amplifiers
The amplifiers used for clinical EMG recording must meet same strict specifications for low-leakage currents as do ECG, EEG, and any other amplifiers used to measure human body potentials. EMG amplifier gains are typically x1000 and their bandwidths reflect the transient nature of the single motor unit (SMU) action potentials. An EMG amplifier is generally…
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Cardioverter Operation & Biomedical Application
When an operator applies an electric shock of the magnitude of that from a dc defibrillator to the patient’s chest during the T wave of the ECG, there is a strong risk of producing ventricular fibrillation in the patient. Because the most frequent use of defibrillation is to terminate ventricular fibrillation, this problem does not…
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5 Established Isolation Architectures for Medical Isolation Amplifiers
Medical isolation amplifiers provide an ultra-low conductive pathway between the input (patient) terminals and the output terminals and ground. This pathway provides what is called ohmic or galvanic isolation for a patient. In medical applications, this isolation is required for reasons of patient safety. The dc resistance between input and output terminals is typically on…
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The Origin of EMG Biosignals
Introduction A key bioelectric signal that has diagnostic significance for various neuromuscular diseases is the electromyogram (EMG), which can be recorded from the skin surface with electrodes identical to those used for electrocardiography, although in some cases, the electrodes have smaller areas than those used for ECG ( <1 mm2). To record from single motor…