Polysilicon wire sensor for biochemical detection with the help of capillary atomic-force-microscopy tip for solution transfer

In this paper, we proposed a polysilicon (poly-Si) wire based biosensor for the detection of glucose and matrix metalloproteinase (MMP) extracted from cancer cells. A focus-ion-beam (FIB) processed capillary atomic-force-microscopy (C-AFM) tip was used to help for transferring trace amount of glucose and MMP solutions onto the exact position of the surface of the poly-Si wire sensor. Glucose solution with different concentrations and MMPs extracted from humans lung adenocarcinoma cells A549 and H1299 were then determined from the current flowing through the poly-Si wire. Due to different amount of hydrogen ions bounded to the poly-Si wire surface when different glucose solutions or MMPs were dropped on the poly-Si wire surface, charge accumulation would occur in the poly-Si wire and causing different current levels been measured. Our experimental data showed that the poly-Si wire sensor is effective and has high sensitivity for glucose and tumor cell MMPs detection when C-AFM tip is used for solution transfer.