Characteristics of chemical and biosensors
- Selectivity. Selectivity is probably the most important feature of a biosensor. Selectivity means that sensor detects a certain analyte and doesn’t react to admixtures and contaminants. Antigen-antibody interaction has the highest selectivity, it is analyte-specific.
- Precision is a characteristic of any scientific device that makes quantitative measurements. Precision is usually characterised in terms of the standard deviation of measurements.
- Signal stability shows the signal drift under constant conditions, which causes an error in measured concentration. Signal stability influences the precision of sensor, it is an important characteristic of a sensor that performs continuous monitoring. Signal drift is usually measured in percent per hour.
- Sensitivity (detection limit) shows the minimal amount (or concentration) of analyte that can be detected.
- Working range is the range of analyte concentrations in which the sensor can operate. Working range of sensor should correlate with the range of possible concentrations analyte in the assay. For example, glucose concentration in blood typically varies from 0.2mM to 20 mM. Working range of glucose sensors shouldn’t be less. If a sensor not only detects the analyte, but measures its’ concentration, linear range is another important characteristic. Linear range is the range of analyte concentrations in which the sensor response changes linearly with the concentration.
- Response time is time required to analyze the assay.
- Regeneration time is the time required to return the sensor to working state after interaction with the sample.
- Number of cycles is the number of times the sensor can be operated. Degradation of biological material is inevitable and it needs to be replaced. In some sensors (e.g. hand-held commercial glucose sensors) transducers are disposable, they need to be changed after each measurement. Other sensors can keep their characteristics for many cycles.
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