Achim Sack
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View article: Locomotion of a Scallop-Inspired Swimmer in Granular Matter
Locomotion of a Scallop-Inspired Swimmer in Granular Matter Open
Understanding swimming in soft yielding media is challenging due to their complex deformation response to the swimmer's motion. We experimentally show that a scallop-inspired swimmer with reciprocally flapping wings generates locomotion in…
View article: Acoustically propelled winged macroparticles
Acoustically propelled winged macroparticles Open
Self-propelled particles harvest and harness energy from their environment, transforming it into a controlled force that propels their motion. We present a mechanism to propel active macroparticles using low frequency noise (10–200 Hz). Th…
View article: Automated Tomographic Assessment of Structural Defects of Freeze-Dried Pharmaceuticals
Automated Tomographic Assessment of Structural Defects of Freeze-Dried Pharmaceuticals Open
The topology and surface characteristics of lyophilisates significantly impact the stability and reconstitutability of freeze-dried pharmaceuticals. Consequently, visual quality control of the product is imperative. However, this procedure…
View article: Granular jamming gripper with integrated suction
Granular jamming gripper with integrated suction Open
Granular grippers can manipulate a wide variety of objects, but need to be pressed on the object to conform to it. If the object is placed on unstable ground, e.g., on sand or water, this step might cause the object to sink or move away fr…
View article: Automated tomographic assessment of structural defects of freeze-dried pharmaceuticals
Automated tomographic assessment of structural defects of freeze-dried pharmaceuticals Open
The topology and surface characteristics of lyophilisates significantly impact the stability and reconstitutability of freeze-dried pharmaceuticals. Consequently, visual quality control of the product is imperative. However, this procedure…
View article: TSS-ConvNet for electrical impedance tomography image reconstruction
TSS-ConvNet for electrical impedance tomography image reconstruction Open
Objective. The objective of this study was to propose a novel data-driven method for solving ill-posed inverse problems, particularly in certain conditions such as time-difference electrical impedance tomography for detecting the location …
View article: Effect of particle size on the suction mechanism in granular grippers
Effect of particle size on the suction mechanism in granular grippers Open
Granular grippers are highly adaptable end-effectors that exploit the reversible jamming transition of granular materials to hold and manipulate objects. Their holding force comes from the combination of three mechanisms: frictional forces…
View article: Effect of Particle Size on the Suction Mechanism in Granular Grippers
Effect of Particle Size on the Suction Mechanism in Granular Grippers Open
Granular grippers are highly adaptable end-effectors that exploit the reversible jamming transition of granular materials to hold and manipulate objects. Their holding force comes from the combination of three mechanisms: frictional forces…
View article: Soft particles reinforce robotic grippers: robotic grippers based on granular jamming of soft particles
Soft particles reinforce robotic grippers: robotic grippers based on granular jamming of soft particles Open
Granular jamming has been identified as a fundamental mechanism for the operation of robotic grippers. In this work, we show, that soft particles like expanded polystyrene beads lead to significantly larger gripping forces in comparison to…
View article: Weight of an hourglass—Theory and experiment in quantitative comparison
Weight of an hourglass—Theory and experiment in quantitative comparison Open
A flowing hourglass changes its weight in the course of time because of the of its center of mass. While this insight is not new, it is frequently said that the effect is tiny and hardly Here, we present a simple experiment that allows the…
View article: Microgravity spreading of water spheres on hydrophobic capillary plates
Microgravity spreading of water spheres on hydrophobic capillary plates Open
\nWe create nearly perfect centimetric spheres of water by splitting a cavity consisting of two metal hemispheres coated with a hydrophobic paint and under-filled with liquid, while releasing the apparatus in free-fall. A high-speed camera…
View article: Dissipation of Energy by Dry Granular Matter in a Rotating Cylinder
Dissipation of Energy by Dry Granular Matter in a Rotating Cylinder Open
We study experimentally the dissipation of energy in a rotating cylinder which is partially filled by granular material. We consider the range of angular velocity corresponding to continous and stationary flow of the granulate. In this reg…