Lars Bumke
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Origami-inspired reprogrammable microactuator system Open
A reprogrammable microactuator system is presented, consisting of antagonistic shape memory alloy (SMA) microactuators for bidirectional folding of miniature-scale tiles following the concept of origami. Additional integrated heatable soft…
SMA Film-Based Elastocaloric Cooling Devices Open
The ongoing trend of miniaturization and increasing power density in miniaturized systems demand for active temperature control and cooling. The cooling technologies utilized today depend on environmentally harmful substances or are bound …
Bistable Actuation Based on Antagonistic Buckling SMA Beams Open
Novel miniature-scale bistable actuators are developed, which consist of two antagonistically coupled buckling shape memory alloy (SMA) beams. Two SMA films are designed as buckling SMA beams, whose memory shapes are adjusted to have oppos…
View article: Exchange biased surface acoustic wave magnetic field sensors
Exchange biased surface acoustic wave magnetic field sensors Open
Magnetoelastic composites which use surface acoustic waves show great potential as sensors of low frequency and very low amplitude magnetic fields. While these sensors already provide adequate frequency bandwidth for most applications, the…
Shape Memory Alloy Thin Film Auxetic Structures Open
Auxetic structures provide an interesting approach to solving engineering problems due to their negative Poisson's ratio, which allows for elongation perpendicular to applied stresses, opposite to a conventional structure's necking behavio…
Thin-Film Superelastic Alloys for Stretchable Electronics Open
Conductive serpentine interconnects comprise fundamental building blocks (e.g., electrodes, antennas, wires) of many stretchable electronic systems. Here we present the first numerical and experimental studies of freestanding thin-film TiN…
TiNiHf/SiO<sub>2</sub>/Si shape memory film composites for bi-directional micro actuation Open
The martensitic phase transformation in Ti40.4Ni48Hf11.6 shape memory alloys is leveraged for bi-directional actuation with TiNiHf/SiO2/Si composites. The shape memory properties of magnetron sputtered Ti40.4Ni48Hf11.6 films annealed at 63…
Coherent Precipitates as a Condition for Ultra-Low Fatigue in Cu-Rich Ti53.7Ni24.7Cu21.6 Shape Memory Alloys Open
Sputtered Ti–rich TiNiCu alloys are known to show excellent cyclic stability. Reversibility is mostly influenced by grain size, crystallographic compatibility and precipitates. Isolating their impact on cyclic stability is difficult. Ti 2 …
Integration of AlN piezoelectric thin films on ultralow fatigue TiNiCu shape memory alloys Open
Cover Feature: Elastocaloric Cooling on the Miniature Scale: A Review on Materials and Device Engineering (Energy Technol. 8/2018) Open
Cool Review: Innovative elastocaloric cooling systems have the potential to meet the rising demand for efficient cooling and temperature control on the miniature scale, such as in microelectronic devices and lab-on-a-chip systems. This Rev…
Phase engineering and supercompatibility of shape memory alloys Open
In recent years examples of unprecedented functional and structural fatigue resistance and lowered hysteresis in shape memory alloys have been achieved by combining conditions of supercompatibility between phases with suitable grain size a…
Sacrificial Template Synthesis and Properties of 3D Hollow-Silicon Nano- and Microstructures Open
Novel three-dimensional (3D) hollow aero-silicon nano- and microstructures, namely, Si-tetrapods (Si-T) and Si-spheres (Si-S) were synthesized by a sacrificial template approach for the first time. The new Si-T and Si-S architectures were …