Figure 2:Schematic diagrams represent the fabrication of impedimetrichCGimmunosensors based on DEP chip following a) method A and b) method B.In the method A, the carbon ink electrode of DEP chip is modified first by using a functional molecule, 1-pyrenebutanoic acid succinimidyl ester (1) and thence MabhCG immobilization via succimidyl ester groups. However, in the method B, the MabhCG is conjugated first with 1 and then dropped directly onto carbon ink working electrode surface of DEP chip.