Category: Biomedical Measurements
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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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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…
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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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Types of EMG Electrodes Commonly Used in Medical Measurements
We have different types of biopotential electrodes that are used in recording electromyographic (EMG) signals from different muscles in the body. The shape and size of the recorded EMG signals depend on the electrical property of these electrodes and the recording location. For non-invasive recordings, proper skin preparation, which normally involves cleansing the skin with…
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Microelectromechanical System Transducers (MEMS)–Based Medical Sensors
Microelectromechanical system transducers (MEMS) are fabricated using solid-state micromachining techniques that are typically employed by the semiconductor industry in the production of integrated circuits (ICs). Related: The application of Microprocessors in Medical Instrumentation A pressure sensor based on MEMS technology is based on the deflection of a micromachined silicon diaphragm mounted on a piezoelectric transducer…
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ECG Electrodes
A typical flexible ECG electrode is composed of certain types of polymers or elastomers that are made electrically conductive by the addition of fine carbon or metal powder. These electrodes are available with pre-pasted AgCl gel for quick and easy application on the skin using double-sided peel off adhesive type. Related: Electrocardiogram (ECG) The common…
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Key Considerations for Biopotential Measurements
Biopotential measurements are done using different types of specialized electrodes. The work of these recording electrodes is to couple the ionic potentials generated inside the body to an electronic instrument. Biopotential electrodes are classified either as non-invasive (skin surface) or invasive (for example microelectrodes or wire electrodes). Related: Types of Electrodes used in Medical…