Fabrication Of Silicon Nanowires And Its Application In Biosensors

It is very important to realize the detection of low concentration biological substances in the fields of medical diagnosis,health monitoring,food safety and national defense.In the early stage of many diseases,the concentration of viruses and tumor markers is very low,and the symptoms of the disease are not so obvious,which is difficult to be detected by traditional technical equipment.The best treatment time is often easily missed after the disease develops in middle and advanced stage,so the detection of viruses and tumor markers in the early or even ultra-early stage is particularly important for the diagnosis and treatment of the disease.In order to achieve ultra-low concentration detection,we developed a novel biosensor based on grid silicon nanowire arrays.During the process of the device,the flow direction of test solution is perpendicular to the silicon nanowire arrays,makes biological material under test through the nanowire arrays,the sports channel is limited in the clearance of the nanowires,reduces the biomass and spatial distance on the surface of the nanowires,and reduces the detection limit of the biosensor,realize the detection of ultra-low concentration in biological samples.By reasonably controlling the size of gold nanoparticles and the density on the surface of silicon wafers,we used CVD method based on VLS growth mechanism to fabricate transversely boron-doped silicon nanowire arrays with controllable diameter and density between wafer grooves.Using the nanowire array,we fabricated a grating biosensor.The lowest limit of detection for PSA was 3.6 f M,and the response time and recovery time were 15.5 s and 10.7 s at a concentration of 0.36 p M,respectively.The device has excellent response differentiation,linearity and stability over a wide concentration range from 3.6 f M to 36 p M.Due to the integration of a large number of nanowires in the gate biosensor,the response current of the device can be increased,and the current can reach the magnitude of ?A under the bias voltage of 1 V,which makes the test more simple and convenient.At the same time,it can effectively restrain the fluctuation of conductance and improve the signal-to-noise ratio,so as to improve the overall stability and reliability of the biosensor.