In recent years, solid-state nanopores have been widely used in biotechnology for detecting single molecules. Here, we studied the influence of membrane thickness and Focused Ion Beam action time on the diameter of silicon nitride nanppores. The results showed that on the 300 nm thick silicon nitride membrane, the minimum pore was 170 nm in diameter; while on thinner membranes with the thicknesses of 200nm and 100nm, the minimum pore diameters were 100nm and 30nm respectively. And on the membrane of a given thickness, the minimum diameter of nanopore is determined by the minimum action time. Therefore the 100 nm membrane thickness is ideal for milling small nanopores.
Nanopore has the proming to be used as the detection senser for the single molecule at single molecular level or the nanoparticles in different meterials. The diameters of the nanopores can be changed in a large rang with the increasing fabrication technology. For this case, the nanopore could be used as particles‘ sizes senser. We used 15nm gold nanoparticles as exsamples to analyze the effects of nanopore/nanoparticle ratio in deionized water. In the detection experiments, we found that the gold nanoparticles would pass through the nanopore in different behaves. Besides, the diameters of the nanopores might effect the precision accuracy of the translocation events. In view of the former results, we notice that on the basis of nanopore detection technique, nanoparticles translocation share many similarities with DNA.