1. A process for making a microarray comprising the steps of: randomly depositing a first sub-population of microbeads on a substrate, wherein all microbeads of the first sub-population comprise a same active agent capable of specifically binding with a target analyte and wherein all microbeads are capable of attaching themselves to the substrate; imaging the spatial position of all microbeads of the first sub-population on the substrate and recording a first set of imaging data in a computer memory indicating the spatial position of all microbeads of the first sub-population on the substrate; after imaging and recording the spatial position of all microbeads of the first sub-population, randomly depositing a second sub-population of microbeads on the substrate, wherein all microbeads of the second sub-population comprise a same active agent capable of specifically binding with a target analyte and wherein all microbeads are capable of attaching themselves to the substrate; wherein the active agent of the second sub-population is different from the active agent of the first sub-population; imaging the spatial position of all microbeads of the first sub-population and the second sub-population on the substrate, and recording a second set of imaging data in a computer memory indicating the position of all microbeads of the first and second sub-population on the substrate; and writing a decoding data set table, prior to an assay procedure being carried out using the microarray, relying solely on differences of the spatial positions of the microbeads between the successive images in the first set of imaging data and the second set of imaging data to determine where a specific microbead in a specific spatial position belongs to the first sub-population or the second sub-population.