Key Performance Requirements of Effective Biomedical Instrumentation Systems

Jun 13, 2020

—

John Mulindi

in Basics of Biomedical Instrumentation Systems

The information obtained from a medical sensor or transducer is usually in form of current intensity, voltage level, frequency or signal phase relative to a standard.

We look at some of the performance requirements considered in biomedical instrumentation systems as discussed below:

To make accurate measurements of voltage, it is necessary to have the input impedance of the measuring device larger than the output impedance of the signal source. This is to minimize the error that would occur if an appreciable fraction of the signal source were dropped across the source impedance.
An accurate measurement of current source signals requires that the source output impedance be larger than receiver input impedance. In an ideal situation, a receiver that exhibits zero input impedance would not cause any disturbance to the current source. Hence, high-impedance current sources are more easily handled than low-impedance current sources.
Generally, the frequency response of the system should be compatible with the operating range of the signal being measured. To process the signal waveform without distortion, the bandpass of the system must include all of the frequency components of the signal that contribute significantly to the signal strength. The range can be determined quantitatively by obtaining a Fourier analysis of the signal.
Electrical signals are usually affected by spurious signals components or noise. Biomedical instruments are designed in such a way that the noise is minimized to enable accurate and sensitive measurement. To extract information from noisy signals, it is necessary to enhance signal-to-noise ratio. Using techniques like bandwidth reduction.
Digital processing is preferred over analog processing. Digital techniques are advantageous over analog techniques e.g. they are not affected by temperature that affects analog devices. The digital devices have a powerful performance since they are able to implement complex algorithms.