Tag: Biomedical Instruments
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How Arterial Tonometer is used for Blood Pressure Measurement
The arterial tonometer is an instrument used to measure arterial blood pressure. It differs from sphygmomanometer in that, rather than measuring the pressure at greatest contraction and greatest heart dilation (systolic and diastolic) it provides continuous measurement throughout the heart’s pumping cycle. Normally, the instrument sensor is placed over a superficial artery; the radial artery…
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Optical Tomographic Imaging
The optical properties of normal and diseased tissues are usually different despite the large variation of values in optical properties of the normal tissues alone. A case in point is the cancerous tissues that manifest significant architectural changes at the cellular and subcellular levels, and the cellular components that cause elastic scattering have dimensions typically…
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The Operation of Fiber-optic Based Blood Gas Sensors
To perform in vivo measurements and to steadfastly analyze blood gases, a small, stable, accurate and bio-compatible sensor is needed that can be inserted in the blood flow of an artery through an arterial cannula and remain in place for several days. Additional, it has to be low cost so that it could be used…
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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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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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Biomedical Sensor Specifications
The need for accurate medical diagnostic procedures places stringent requirements on the design and use of biomedical sensors. Depending on the intended application, the performance specifications of a biomedical sensor may be evaluated in vitro and in vivo to ensure that the measurement meets the design specifications. The following definitions are typically employed when describing…
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Atomic Force Microscopy (AFM)
This technique allows the mapping of surfaces on a molecular or atomic scale. It can also be adapted to measure interatomic forces. The principle of operation of AFM is discussed as follows: A silicon or silicon nitride probe with a fine (approximately 1 nm radius) tip is connected to a flexible cantilever. The molecular or…
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What is a Biosensor?
This is a biological sensor that has the following features: Biosensors are typically miniature and include monitoring of blood gas and biochemical concentrations additionally, physical quantities such as force, shear, potential, etc. Biosensors can be divided into those that measure electrical properties e.g. pH meters, CO2 electrodes, O2 electrodes, field-effect transistor-based biosensors, etc. and those…
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The Process of Setting up a PET scan
The ability of a PET scanner to target specific functions or objects e.g. tumour makes it a very effective tool in non-invasive medical imaging and diagnostics. The process involves using radionuclides, so PET scanners aren’t available at every medical facility. Related: Radionuclide Imaging Techniques The process of setting a PET scan involves the following steps:…