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Title: Steerable Propulsion of Disk-Like Nanojet with Nozzle Nanoengines

Liangxing Hu

Nanyang Technological University, Singapore

Biography

Dr. Liangxing Hu (Ph.D.-micro/nano technology) obtained his Bachelor Degree from Harbin Institute of Technology,China, in 2012. He has completed his Ph.D. at the age of 28 from Nanyang Technological University, Singapore. Currently, he is a research fellow in MAE at Nanyang Technological University. His research interest is the characterization of catalytic nanomotor based NEMS device for drug delivery.

Abstract

A novel nanojet with singular nozzle nanoengine consisting of gold (Au), nickel (Ni) and platinum (Pt) is designed and fabricated. Au and Ni are shaped as a concentric disk with 12 µm in diameter. The thicknesses of Au- and Ni-disks are 0.2 and 0.1 µm, respectively. Singular Pt nozzle nanoengine forms a cylindrical chamber and is only on one side of the Au-Ni disk. The diameter, bottom-thickness, wall-height and wall-thickness of the nozzle nanoengine are 3, 0.3, 1.5 and 0.3 µm, respectively. A steerable propulsion mechanism for the Au-Ni-Pt nanojet is shown. Without the presence of hydrogen peroxide (H2O2), the nanojet suspended in deionized (DI) water is stationary. After the addition of H2O2 into DI water, oxygen (O2) bubbles are generated at the Pt-surface (the nanojet and O2 bubbles have a joint velocity of v1). The generated O2 bubbles grow bigger (growing state). At this state, the nanojet and O2 bubbles have a same velocity of v2. When O2 bubbles reach a certain diameter, they detach from the surface of the nanojet (detaching state). The nanojet has a velocity of v3, while O2 bubbles have a different velocity of v0. According to the Momentum Conservation Law and the Momentum Theorem, a driving force Fdrive is generated, resulting from momentum change induced by the detachment of O2 bubbles, to thrust the nanojet propelling forward. The nanojet is equipped with singular nozzle nanoengine, resulting in the total driving force Fdrive is not well aligned with the drag force  Fdrag. Hence, the Au-Ni-Pt nanojet propels forward circularly, as shown. At steady state, the nanojet will continuously propel forward at a speed of v.

Audience take away:

• MEMS fabrication technique
• Bubble propulsion mechanism
• Characterization of nanojets