Author: John Mulindi
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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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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:…
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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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Radionuclide Imaging Techniques
The radionuclide imaging devices place radionuclides, called tracers, within the body. We have 3 types of imaging that include the following: Let’s discuss briefly each of the above listed imaging techniques: Single Photon Emission Computed Tomography (SPECT) SPECT uses a radionuclide with relatively longer half-life. (The half-life is the time, it takes half the radionuclides…
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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…
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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…