DNA microarray is made by spotting specific DNA sequence or known as probe onto a surface particularly a solid surface like glass, plastic slides or membrane. Microarray works by using the principle of hybridisation of complementary DNA sequences. 

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             Two sets of mRNAs from two difference sources which are to be examined are extracted and reverse transcript to get cDNA which are more stable. The two sets of cDNAs are fluoresces with two different colours in order to differentiate them from each other and then they are allowed to mix.

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             The mixture of cDNA is then transferred to the microarray chip for hybridization. After hybridisation process, the microarray chip is washed to remove unhybridised cDNAs. Then, the microarray chip is scanned with laser activating the fluorescent dye of sample cDNA. Finally, the result is captured and can be analysed.