Wissenschaftliche Artikel der BAM
Filtern
Dokumenttyp
Sprache
- Englisch (3)
Referierte Publikation
- ja (3)
Schlagworte
- Giant magnetoresistance (3) (entfernen)
Organisationseinheit der BAM
Heterodyne Eddy Current Testing Using Magnetoresistive Sensors for Additive Manufacturing Purposes
(2020)
In recent years additive manufacturing technologies have become widely popular. For complex functional components or low volume production of workpieces, laser powder bed fusion can be used. High safety requirements, e.g. in the aerospace sector, demand extensive quality control. Therefore, offline non-destructive testing methods like computed tomography are used after manufacturing. Recently, for enhanced profitability and practicality online non-destructive testing methods, like optical tomography have been developed. This paper discusses the applicability of eddy current testing with magnetoresistive sensors for laser powder bed fusion parts. For this purpose, high spatial resolution giant magnetoresistance arrays are utilized for testing in combination with a single wire excitation coil. A heterodyne principle minimizes metrology efforts. This principle is compared to conventional signal processing in an eddy current testing setup using an aluminum test sample with artificial surface defects. To evaluate the influence of the powder used in the manufacturing process on eddy current testing and vice versa, a laser powder bed fusion mock-up made from stainless steel powder (316L) is used with artificial surface defects down to 100 µm. This laser powder bed fusion specimen was then examined using eddy current testing and the underlying principles.
Imperceptible magnetic sensor matrix system integrated with organic driver and amplifier circuits
(2020)
Artificial electronic skins (e-skins) comprise an integrated matrix of flexible devices arranged on a soft, reconfigurable surface. These sensors must perceive physical interaction spaces between external objects and robots or humans. Among various types of sensors, flexible magnetic sensors and the matrix configuration are preferable for such position sensing. However, sensor matrices must efficiently map the magnetic field with real-time encoding of the positions and motions of magnetic objects. This paper reports an ultrathin magnetic sensor matrix system comprising a 2 × 4 array of magnetoresistance sensors, a bootstrap organic shift register driving the sensor matrix, and organic signal amplifiers integrated within a single imperceptible platform. The system demonstrates high magnetic sensitivity owing to the use of organic amplifiers. Moreover, the shift register enabled real-time mapping of 2D magnetic field distribution.
The current establishment of stretchable electronics to form a seamless link between soft or even living materials and the digital world is at the forefront of multidisciplinary research efforts, bridging physics, engineering and materials science. Magnetic functionalities can provide a sense of displacement, orientation or proximity to this novel formulation of electronics. This work reviews the recent development of stretchable magnetic field sensorics relying on the combination of metallic thin films revealing a giant magnetoresistance effect with elastomeric materials. Stretchability of the magnetic nanomembranes is achieved by specific morphologic features (e.g. wrinkles or microcracks), which accommodate the applied tensile deformation while maintaining the electrical and magnetic integrity of the sensor device. The entire development, from the demonstration of the world’s first elastically stretchable magnetic sensor to the realization of a technology platform for robust, ready-to-use elastic magnetosensorics is described. Soft giant magnetoresistive elements exhibiting the same sensing performance as on conventional rigid supports, but with fully strain invariant properties up to 270% stretching have been demonstrated. With their unique mechanical properties, these sensor elements readily conform to ubiquitous objects of arbitrary shapes including the human skin. Stretchable magnetoelectronic sensors can equip soft and epidermal electronic systems with navigation, orientation, motion tracking and touchless control capabilities. A variety of novel technologies, like electronic skins, smart textiles, soft robotics and actuators, active medical implants and soft consumer electronics will benefit from these new magnetic functionalities.