The relationship between thin film fragmentation and buckle formation: Synchrotron-based in situ studies and two-dimensional stress analysis

Frank, Stephan; Handge, Ulrich A.; Olliges, Sven; Spolenak, Ralph

doi:10.1016/j.actamat.2008.11.023

Cited by 117 publications

(67 citation statements)

References 46 publications

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“…As described in chapter 2.4.1, random micro fracture of thin and flat metal films on elastomeric substrates is typically applied to fabricate highly compliant interconnects for stretchable electronic platforms 102,141,211 . There are also fundamental investigations of periodic microcrack formation in thin metal films on polymeric substrates 137,138,212,213 . However, a pre-determination of crack formation to obtain highly stretchable meander-like patterns was not obtained so far.…”

Section: Microcrack Formation Mechanismmentioning

confidence: 99%

Stretchable Magnetoelectronics

et al. 2011

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Abstract:In this work, stretchable magnetic sensorics is successfully established by combining 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), 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-wide first elastically stretchable magnetic sensor to the realization of a technology platform for robust, ready-touse elastic magnetoelectronics with fully strain invariant properties, is described. The prepared soft giant magnetoresistive devices exhibit the same sensing performance as on conventional rigid supports, but can be stretched uniaxially or biaxially reaching strains of up to 270% and endure over 1,000 stretching cycles without fatigue. The comprehensive magnetoelectrical characterization upon tensile deformation is correlated with in-depth structural investigations of the sensor morphology transitions during stretching.With their unique mechanical properties, the elastic magnetoresistive sensor elements readily conform to ubiquitous objects of arbitrary shapes including the human skin. This feature leads electronic skin systems beyond imitating the characteristics of its natural archetype and extends their cognition to static and dynamic magnetic fields that by no means can be perceived by human beings naturally.Various application fields of stretchable magnetoelectronics are proposed and realized throughout this work. The developed sensor platform can equip soft electronic systems with navigation, orientation, motion tracking and touchless control capabilities. A variety of novel technologies, like smart textiles, soft robotics and actuators, active medical implants and soft consumer electronics will benefit from these new magnetic functionalities. Michael Melzer: Stretchable MagnetoelectronicsOutline 4

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Section: Microcrack Formation Mechanismmentioning

confidence: 99%

Stretchable Magnetoelectronics

et al. 2011

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“…As it has been shown by many research groups Frank et al, 2009;Marx et al, 2015b), in situ XRD tensile straining can provide useful information on how thin film or coating thickness, microstructure, and deposition methods influence mechanical stresses and strains of flexible electronic materials. From the evolution of the lattice strains during straining, clear ductile or brittle material behavior is determined.…”

Section: Methodsmentioning

confidence: 99%

Electro-Mechanical Testing of Conductive Materials Used in Flexible Electronics

2016

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The use of flexible electronics has increased in recent years. In order to have robust and long lasting flexible displays and sensors, the combined electro-mechanical behavior needs to be assessed. The most common method to determine electrical and mechanical behavior of conductive thin films used in flexible electronics is the fragmentation test or uniaxial tensile straining of the film and substrate. When performed in situ, fracture and deformation behavior can be determined. The use of in situ electrical resistance measurements can be informative about the crack onset strain of brittle layers, such as transparent conductors, or the stretchability of metal interconnects. The combination of in situ electrical measurements with in situ X-ray or confocal laser scanning microscopy can provide even more information about the failure mechanisms of the material systems. Lattice strains and stresses can be measured with X-rays, while cracking and buckle delaminations can be studied with confocal laser scanning microscopy. These new combinations of in situ methods will be discussed as well as methods to quantify interfacial properties of conductive thin films on polymer substrates. The combined techniques provide valuable correlated electrical and mechanical data needed to understand failure mechanisms in flexible devices.

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“…[22,23] In our tests, deflection is currently restricted within a very small range. Assumed that the segmented coating mainly undertakes tensile stress, [24] as illustrated in Fig.…”

Section: Evaluation Of Interface Fracture Toughnessmentioning

confidence: 99%

Multiscale monitoring of interface failure of brittle coating/ductile substrate systems: A non-destructive evaluation method combined digital image correlation with acoustic emission

Mao

Zhou

et al. 2011

Journal of Applied Physics

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In this paper, we proposed a non-destructive evaluation method combined digital image correlation (DIC) with acoustic emission (AE) techniques, which was used to in-situ monitor interface failure and internal damage of brittle coating/ductile substrate systems under different size scales by bending tests. Measurements of full/local field strain fields by DIC in the segmented coating clearly show typical heterogeneous failure process and successfully clarify several controversial assumptions introduced in theoretical models. AE results effectively reveal the damage evolution of cracking nucleation, propagation and coating spallation of the ceramic coating by combining wavelet transform with traditional parameter analysis under external loads. The conclusions show that there is a good relationship between digital image correlation and acoustic emission signals with the aid of test time during the coating failure, which can be applied to judge cracking formation and coating delamination, and to obtain the most important critical experimental data. As an example, several crucial mechanical properties of a thermal barrier coating system including fracture strength, fracture toughness and shear strength were determined.

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The relationship between thin film fragmentation and buckle formation: Synchrotron-based in situ studies and two-dimensional stress analysis

Cited by 117 publications

References 46 publications

Stretchable Magnetoelectronics

Stretchable Magnetoelectronics

Electro-Mechanical Testing of Conductive Materials Used in Flexible Electronics

Multiscale monitoring of interface failure of brittle coating/ductile substrate systems: A non-destructive evaluation method combined digital image correlation with acoustic emission

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