Question

A biomedical sensor does not seem to give correct information. List some potential causes for this problem.

Answer 1

1)Presence of interfering ions

For a chemical sensor to be ideal,it should only show the signal corresponding to the analyte.But,in laboratory practice,interference can occur.

2)Leakage of the chemical interface components

The design of the sensor should be such that,an appropriate chemical interface (as in the form of a membrane)should be there, in which the analyte recognition process takes place.So there are chances of leakage of the chemical interface component into the sample.

3)Sample composition

This can influence the parameters in the sensor response function or even cause its damage or malfunction. For example, physical nature of the ion-selective membrane can be changed by deposition of proteins present in a biological sample.This causes either a delay in sensor response or no response at all.

4)Influence of pH

In some cases the sensor can work only in a given range of pH and an appropriate buffer or pH correction should be applied for the purpose of avoiding errors

5)Absence of ambient light

If the measurements of a chemical sensor are carried out in a daylight environment,changes in the optical radiation can influence both optical and potentiometric sensors and cause errors in measurement

6)Influence of temperature

Temperature changes can cause error as it influences the characteristics of a sensor or a transducer, the potential of a reference electrode (in the case of potentiometric sensors) and the whole measuring system.

7)Other environmental influences

These include vibration,shock,altitude changes etc which can influence the results produced.