Magnetic field assisted roll-up of high aspect ratio nanomembranes

Datum

07.05.2019

Zeit

13:30 - 14:30

Sprecher

Felix Gabler

Zugehörigkeit

IFW Dresden

Sprache

en

Hauptthema

Materialien

Host

Kristina Krummer-Meier

Beschreibung

Rolled-up nanotechnology has been considered a powerful strategy in manufacturing micro devices with various fields of application ranging from passive electronics through photonic resonators to biomedical platforms for cell study and detection [1]. Especially micro energy storage (MES) devices such as capacitors, supercapacitors and batteries can benefit from the ability of rolled-up nanotechnology to self-assemble 2D patterned nanomembranes into compact 3D tubular architectures by relaxation of mechanical strain as demonstrated by the works on rolled-up electrostatic capacitors [2-3]. The performance potential of MES devices fabricated by rolling up nanomembranes is tremendous since the electrically active area scales up with nanomembrane length while the final device footprint remains almost constant (Fig. 1a). However, up to now there is no technology that enables the roll-up of nanomembranes with high length-to-width aspect ratio in a unidirectional and reproducible fashion. This is mainly because a nanomembrane under isotropic strain will inherently try to avoid rolling perpendicular to its short side as more strain energy can relax when rolling from the long side or in a tilted way. In this seminar, I will introduce a novel approach to roll up high aspect ratio nanomembranes with unprecedented control and speed. To release the nanomembranes of several millimeters in length within a reasonable time, a wet release platform based on encapsulated methyl cellulose with roll-up speed up to 500 µm/s was applied. In order to achieve unidirectional rolling over such length scales, ferromagnetic material was incorporated into the nanomembrane and the self-assembly was performed under influence of an external magnetic field. This magnetic field assistance helps to make tilted rolling energetically unfavorable (Fig 1b). Furthermore, observed interactions between the magnetized windings were studied and tuned by engineering the initially planar nanomembrane shape to stabilize axial movement of windings (Fig. 1c). Finally, the developed technology was used to assemble 10 mm long nanomembranes into Al2O3 dielectric capacitors (Fig. 1d) having 0.018 mm² footprint and a CV product of 0.5 mFV/cm² with 90% overall assembly yield outperforming previous works as well as industry’s smallest multilayer ceramic capacitor (MLCC).

Links

• Seminars at the IFW

Letztmalig verändert: 05.05.2019, 18:53:40