The invention relates to a method of assembling a biosensor device comprising two or more biosensor units, wherein each unit comprises one or more biosensors comprising one or more carbon nanotubes (CNTs) coated with nucleic acid and one or more sensor molecules coupled to the nucleic acid, wherein each one of the one or more sensor molecules is capable of binding to a target molecule in a sample. Each biosensor unit is capable of detecting a different target molecule in a sample, and each unit comprises one or more biosensors each capable of detecting the same target molecule. The invention further relates to biosensor devices and methods for detecting target molecules in a sample using the same.