*1.2.4 Sensitivity*

The minimum amount of analyte that can be detected by a biosensor defines its limit of detection (LOD) or sensitivity. In several medical and environmental monitoring applications, a biosensor is required to detect analyte concentrations as low as nanogram/milliliter (ng/ml) or even femtogram/milliliter (fg/ml) to confirm the presence of traces of analytes in a sample [2]. For instance, a prostate-specific antigen (PSA) concentration of 4 ng/ml in the blood is associated with prostate cancer for which doctors suggest biopsy tests. Hence, sensitivity is considered to be an important property of a biosensor [2].

*Recent Advances in Biosensing in Tissue Engineering and Regenerative Medicine DOI: http://dx.doi.org/10.5772/intechopen.104922*

#### *1.2.5 Linearity*

Linearity is the feature that shows the accuracy of the measured response (for a set of measurements with different concentrations of the analyte) to a straight line, mathematically represented as y = mc, where c is the concentration of the analyte, y is the output signal, and m is the sensitivity of the biosensor [2]. Linearity of the biosensor can be associated with the resolution of the biosensor and the range of analyte concentrations under test. The resolution of the biosensor is defined as the smallest change in the concentration of an analyte that is required to bring a change in the response of the biosensor. Depending on the application, a good resolution is required as most biosensor applications require not only analyte detection but also the measurement of concentrations of the analyte over a wide working range. Another term associated with linearity is a linear range, which is defined as the range of analyte concentrations for which the biosensor response changes linearly with the concentration [2]. These features are essential for the biosensors' proper functioning, which can be used for various applications.
