**5. Arrays according to the applications**

Bearing in mind the final application, protein microarrays are classified into two categories: Analytical arrays and functional arrays.

## **5.1. Analytical arrays**

These arrays are normally used to quantitatively identify the presence of multiples protein in one single assay. Commonly, the main application is the detection of differently expressed proteins and their abundance in different samples. Biomarkers are determined by this type of arrays. They are biometric measurements, including molecular signatures, that predict a biological or clinical condition for example, normal or pathologic, often with potential diagnostic or prognostic value [9, 10, 16].
