Direct writing of suspended nanowires using coaxial electrohydrodynamic jet with double tip assistance

One-dimensional nanostructures with precise size and morphology exhibit unique electronic, optical, and mechanical properties that make them highly attractive for a wide range of applications in micro/nanodevices. However, traditional micro/nanostructures processing techniques like photolithography, nanoimprint are complex. Hence, we propose a novel method called double tip-assisted focused coaxial electrohydrodynamic (CEHD) printing technology to fabricate consistent nanopatterns. This method utilizes a focused-tip to enhance the strength of the electric field and minimizes reflux (internal fluid), thereby improving the stabilization of the CEHD jet. Additionally, the guide-tip facilitates controlled deposition during the fabrication process. The focused-tip length exceeding the coaxial needle ranges from 150 to 300 µm was optimized through simulations and verified by experiments. By using the tip-assisted focused method, the working voltage and minimum flow necessary to form a stable cone-jet are reduced. This technique enabled the direct printing of united aligned suspended PZT (PbZr_1-xTi_xO₃) nanowires (about 100 nm) on a silicon dioxide substrate under optimal experimental conditions. The double tip-assisted focused CEHD printing technique offers a highly effective method for fabricating micro/nanostructures, holding great promise for applications in micro/nano-electromechanical systems.