ELISA (enzyme-linked immunosorbent assays) and FIA (fluorescent immunoassays) are two methods of immunoassays. Immunoassays are standard tools used in clinical diagnostics. These tests rely on the specific detection of either the antibody or antigen, and are commonly performed by labeling the antibody/antigen of interest through various means such as fluorescent or enzymatic labels. However, washing, mixing, and incubation always take a great deal of time. When integrated in microfluid biodisks, the detection times become extremely short and such types of tests can be widely used in this area. In ELISA method, enzymes are used to produce a detectable signal from an antibody–antigen complex. At the first step, any antigen present will bind to capture antibodies which have been coated on the channel's surface. Then, detecting antibodies added to bind to the antigen. The enzyme-linked secondary antibody follows the detecting antibodies and binds to them. Finally, when substrate is added, it will be converted by enzyme to a detectable form. Base on this principle, Sergi Morais achieved multiplexed microimmunoassays on a digital versatile disk. This multiplexed assay could achieve detection limits (IC10) of 0.06μg/L and sensitivities of (IC50) 0.54μg/L. In addition to typical ELISA assays, fluorescent immunoassays (FIA) are also introduced on a centrifugal microfluidic device. The principle of FIA is almost the same with ELISA; the most significant difference is that fluorescence labels are used instead of enzymes. Nucleic acid analysis Nucleic acid sensing using gene-specific nucleic acid amplification with a fluorescence dye or a probe, nucleic acid microarrays, such as DNA microarrays, have become important tools for genetic analysis, gene expression profiling, and genetic-based diagnostics. In the gene-specific nucleic acid amplification, standard PCR or isothermal amplification, such as loop-mediated isothermal amplification (LAMP), is used to amplify the target genetic marker with the DNA-binding fluorescence dye or a sequence-specific probe is applied for signal generation. The fluorescence can be detected in a modified CD/DVD drive or a disc device. In the nucleic acid microarrays, the process of probe immobilization and signal amplification can be separated into five steps. The surface of the microchannel is first irradiated with UV light in the presence of ozone to produce a hydrophilic surface with a high density of carboxylic acid groups (step 1). Then, the probe molecules (biotin, DNA, or human plasma IgG) are covalently attached to the polycarbon surface via amide coupling (step 2). Later, the target molecules are labeled with fluorescent tags