If you are intrested in mature biofilm you can use the classical crystal violet assay, for example see Runchi et al., 2017

Article Acinetobacter baumannii Biofilm Formation in Human Serum and...

If you are interested in the early stages (attachment) see the recent paper by Nimrod Shteindel

Nazmul Islam

you can find your answer in page 54 of CLSI *(clinical and laboratory standards institute) rules and you can use the classical crystal violet assay in second attached file

you can find a protocol for Acinetobacter baumannii biofilm formation in a 96-well microtitre plate as following pdf.

Best regrades

Hi Nazmul,

I believe you can try this simple method:

Article Synthetic DNA molecules in biosensing of biofilms

Good luck,