Fabrication of glycerol liquid droplet array by nano-inkjet printing method

We have studied a local deposition method based on dynamic-mode AFM using a hollow tip with an aperture. In this method, liquid droplets are deposited onto a conductive substrate through the aperture by applying an electric voltage pulse and are imaged using the same AFM tip immediately after the deposition. In this study, we applied this method to local deposition of a glycerol solution, which can be utilized in the printed electronics and the biosensor fabrication technology. The solution in the hollow was covered with a hydrophobic ionic liquid with an extremely low vapor pressure to prevent the evaporation of the solution because the quick evaporation heavily affected the dynamic-mode AFM operation. We succeeded in the stable deposition of an array of ultrasmall droplets, which contained an added salt and possible involatile residues in the glycerol solution.