The Fabrication Of 1-D Semiconducting Nanomaterial Field-effect Transisor Biosensor

Biochemical sensors have a lot of potential applications in many fields like healthcare,agricultures,environmental protection,industry and military applications.The biochemical sensors based on one-dimensional(1-D)semiconducting nanomaterials(nanowires or nanotubes)have attracted great attention because they are high sensitive,real-time,easily integrated and label-free for the detection of biomolecules.The key of fabrication of nanowire-based biochemical sensors is the fabrication of nanowire-based FETs,and there are top-down and bottom-up methods to fabricate nanowire/nanotube FETs,and the top down methods is to fabricate the nanowire directly by photolithography&etching,which is complex and costly.In addition,bottom up method is to fabricate NW devices by an easy and cheap way of assembling the synthesized nano wires or nanotubes.However,it is still immature to meet the demand for application.Thus,this research focus on the problems existed in the assemble and fabrication processes and on the optimization of dielectrophoresis processes?The synthesis of one-dimensional nanomaterials,the assembly methods of 1-D nanomaterials and the principle of FET biosensors and the important principle that need to be considered during the fabrication and application of Nanowire-based FET biochemical sensors,was firstly analyzed.Then the nanowire biosensors array under the microfluidic chip was designed,and the experimental scheme to assemble 1-D nanomaterials was designed based on dielectrophoresis.The proportion of metallic SWNTs is higher in the carbon nanotube FETs(CNFETs)assembled by dielectrophoresis than the metallic SWNTs in the solution.The reason is that the dielectrophoresis force applied on M-SWNT is much higher than that on applied on the semiconducting SWNT,thus the M-SWNTs is collected by the dielectrophoresis,to solve this problem we propose a gate voltage assisted dielectrophoresis method to increase the dielectrophoresis force on the S-SWMTs.At the same time,the photo response characteristic of ZnO nanowire photodetector enhanced by coating the nanowire device by photoresist to prevent the bad influence of oxygen and H2O,which is absorbed on the surface of ZnO nanowires.In addition,the results show that the performance of CNFET assembled by gate voltage assisted methods is improved.The On/Off ratio of CNFET improved to 59 from 1.3.Moreover,the recovery time of ZnO nanowire photodetector decreased to several seconds from hundred minutes.