Study On Curl Microsprings Based On Nanometer Thin Films

Micro/nano structures, such as micro/nano-dots, wires, rods and sheets, have been intensely investigated due to their potential applications in the fields including physics, optics, sensing and microelectronics. During the past decade, rolled-up nanotechnology, which takes advantage of both Bottom-Up and Top-Down methods, has been employed to fabricate unique3D microstructures by rolling up pre-strained nanomembranes upon release from a sacrificial layer. In this thesis, novel rolled-up microstructures have been successfully fabricated and their unique properties have been investigated.For the first time, Ti microsprings were fabricated by deterministic rolling of anisotropic strain-engineered nanomembranes via glancing angle deposition (GLAD). The parameters of microsprings can be well controlled. The diameter increases with the thickness increasing, and the helicity angle and the chirality are determined by the misaligned angle between the orientation of the strip and the preferable rolling direction.A liquid flow rate sensor was designed based on that Ti microsprings can be stretched when placed into flow water. The relationship between the elongation of Ti microsprings and flow rate was quantatively analyzed. Results demonstrate that Ti microsprings show a superelasticity behavior with a good reliability.Polyvinyl alcohol-poly (acrylic acid)(PVA-PAA)/metal micro-scrolls (springs and tubes) were fabricated by rolled-up nanotechnology. Stimuli-responsive behavior of micro-scrolls was demonstrated by rolling and unrolling caused by the volume change of the PVA-PAA hydrogel in response to environmental fluids. Moreover, the strain of PVA-PAA layer in microtubes and microsprings during the deformation was calculated. It is found that the strain in microsprings is smaller than that in microtubes due to the partial strain relaxation perpendicular to the rolling direction in microsprings.