Figure 5.

MoS₂-based field-effect transistor (FET) biosensor device. (a) Schematic diagram of MoS₂-based FET biosensor. For biosensing, the dielectric layer covering the MoS₂ channel is functionalized with receptors for specifically capturing the target biomolecules. The charged biomolecules after being captured induce a gating effect, modulating the device current. An electrolyte gate in the form of an Ag/AgCl reference electrode is used for applying the bias to the electrolyte. The source and drain contacts are also covered with a dielectric layer to protect them from the electrolyte (not shown in this figure). (b) Optical image of a MoS₂ flake on 270 nm SiO₂ grown on degenerately doped Si substrate. Scale bar, 10 μm. (c) Optical image of the MoS₂ FET biosensor device showing the extended electrodes made of Ti/Au. Scale bar, 10 μm. (d) Image and schematic diagram (inset figure) of the chip with the biosensor device and microfluidic channel for containing the electrolyte. Inlet and outlet pipe for transferring the fluid and the reference electrode are not shown in the figure. Reprinted with permission from ref. [26]. 2014 American Chemistry Society.