Magnetoactive elastomers (MAEs) are hybrid materials consisting of micrometre-sized ferromagnetic particles embedded in a polymer matrix that can change their physical properties by exposure to a magnetic field. They have many potential applications such as control of surface wettability, adhesion and friction, and can be used in droplet-based microfluidics, soft robot locomotion and more. MAEs can be structured using techniques like replica moulding, magnetic particle-assisted moulding, magnetic micropillar bonding and spray coating, but there are challenges in the additive manufacturing of MAEs. There is a need for alternative microstructuring methods to expand the applicability of MAEs.

This 2021 experiment makes use of the Memmert universal oven UF30, part of the company’s drying oven series. The full study is available here.

Laser-based direct micromachining (LDM) is a process used to fabricate magnetoresponsive lamellar surface structures. The process involves impinging the surface with high-intensity laser pulses at a preselected angle of incidence using a high-speed scanning head.

The LDM process allows for the creation of a wide range of microstructure geometries such as parallel lamellae, arrows, zigzag and pillars with symmetrical or asymmetrical cross-sections. The lateral dimension of the structures is typically 50 µm, while the height is more than 200 µm.

The LDM process is based on the absorption of the high-intensity laser light and the subsequent fast heating of the material above evaporation temperature. The volume of the ablated material depends on the laser beam diameter and pulse energy. The heterogeneous properties of the material being machined present a challenge for consistent ablation and a laser power of 70% of the maximum power was selected in preliminary experiments to effectively ablate the material while minimising heat-affected zones and excessive fragmentation.

Experiments showed that it is possible to produce structures with a large height-to-width ratio, up to 6:1. The structures have a low modulus of elasticity, allowing the lamellae to align with the direction of an applied magnetic field. The results also showed that the depth of the grooves linearly depends on the number of repetitions of the laser beam, with a minimum lamella thickness of about 20 µm and a maximum depth of 300 ± 14 µm. The groove width remained relatively constant, regardless of the depth of the lamellae.

The results of the experiments show that the LDM process is an effective way to produce magnetoresponsive lamellar surface structures with a wide range of geometries and high slenderness. However, further research is needed to address limitations such as the minimum lamella thickness, which is limited by the heterogeneous composition of the material being machined.

A new laser-based method for creating structured magnetic actuation and emission (MAE) surfaces has been developed. The process is direct and enables the fabrication of complex small structures. The practicality of the technology is demonstrated by creating lamellar microstructures with a high aspect ratio, which can be bent by a weak magnetic field. The sliding angle of a water droplet on the structures can be controlled by magnetic fields, making it suitable for use in applications like smart surfaces, microfluidic devices, and soft robotics. The technology opens up new opportunities for further exploration and utilisation.

This article describes the preparation and characterization of magnetic anisotropy elastomer (MAE) samples. The samples were synthesised using a specific blend of ingredients, including soft-magnetic carbonyl iron powder (CIP) and silicone-based polymers.

The mixture was thoroughly blended and poured onto a polyvinyl chloride (PVC) foil and then cured in a Memmert UF30 universal oven. The surface of the samples was then laser processed using a nanosecond pulsed Nd:YAG laser. The structure of the MAE samples was characterised using a zoom stereo microscope and a custom experimental setup that measured sliding angles. All statistical analysis was performed using Python. The Memmert UF30 oven played a crucial role in curing the MAE samples and ensuring the final product was of high quality.

The Memmert Universal oven, part of its drying oven series, is a versatile lab oven with precise and gentle temperature control. It is available in 9 model sizes with a volume range of 32 to 1060 litres, and two model variants: SingleDISPLAY and TwinDISPLAY. The oven features a temperature range of up to +300°C, and users can choose between natural convection or forced air circulation. The oven is easy to operate with an intuitive menu, and features programmable temperature and air exchange ramps, and a pre-heated fresh air system that prevents temperature fluctuations.

The oven is made with high-quality, corrosion-resistant stainless steel, and offers a range of options for programming and documentation using interfaces, integrated data logger, and AtmoCONTROL software. It also comes with a 3-year worldwide guarantee. Additionally, the Um model can be used as a medical device for heating fango, silicate, and APS packs for physical therapy.