Femtosecond laser-contoured micro-strain gages

Heide, Chresten von der; Grein, Maria; Dietzel, Andreas

doi:10.1016/j.mee.2019.05.002

Cited by 6 publications

(5 citation statements)

References 12 publications

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“…The evaluated substrates were ceramic substrates (Al 2 O 3 , Kyocera Fineceramics GmbH, Esslingen am Neckar, Germany), polyimide foils of 30 µm thickness (DUPONT TM Kapton ® HN, DuPont de Nemours, Neu Isenburg, Germany), and foils of 9 µm thickness fabricated by spin-on polyimide precursor (HD Microsystems PI 2611, HD MicroSystems TM , Neu-Isenburg, Germany) adhered to a 4"-borofloat glass wafer with chromium bonding layer (according to [15]). Structuring of substrates, necessary for electrical characterization, was realized by adherent shadow masks, shown in Figure 1.…”

Section: Methodsmentioning

confidence: 99%

Niobium-Containing DLC Coatings on Various Substrates for Strain Gauges

et al. 2019

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Niobium-containing diamond-like carbon films (a-C:H:Nb) were deposited in a hybrid plasma-enhanced chemical vapor deposition (PECVD) and direct-current magnetron sputtering (DCMS) process, using a niobium target in an argon/acetylene atmosphere on industrial polyimide foil, spin-coated polyimide foil, and alumina substrates. While the coating on the industrial foil tends to crack, the thin films on the spin-coated polyimide and the ceramic substrates showed good adhesion, as well as a smooth and dense topography. Investigations of the electrical properties revealed their suitability as biocompatible sensor materials in strain gauges, with a gauge factor of up to 3.2 and a temperature coefficient of the electrical resistance (TCR) of −200 ppm/K.

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Section: Methodsmentioning

confidence: 99%

Niobium-Containing DLC Coatings on Various Substrates for Strain Gauges

et al. 2019

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“…This can yield sensor structures or help to separate conductive areas. Because very little material must be removed, line ablation, which we call contour cut [19] is a time and cost effective technique. For line ablation laser pulses are placed along a line -each pulse overlapping its predecessor as defined by the parameter ϕ.…”

Section: Line Ablationmentioning

confidence: 99%

“…This relation is commonly used to calculate (by squared error regression with y = a • ln(x) + b [6]) effective pulse radius and threshold fluence for bulk material abrasion or laserinduced surface modifications but has some limitations when it comes to thin film ablation Jee et al have shown that material specific threshold fluence diminishes with increasing number of incident pulses [15]. This holds true for coating and substrate, which is why large pulse overlap ablations often result in substrate damage.…”

Section: Further Relevant Ablation Parametersmentioning

confidence: 99%

Methodology of selective metallic thin film ablation from susceptible polymer substrate using pulsed femtosecond laser

et al. 2020

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Electronic devices on flexible polymeric substrates allow new fields of applications. A maskless and flexible structuring process for such systems is offered by ablation using ultra-short pulse laser irradiation. Hereby, certain areas of a functional thin film coating (e.g. nickel-chromium) are locally removed from a substrate (e.g. polyimide) to yield the needed device structures. Micro laser patterning quality is influenced by the beam properties (beam profile, fluence) as well as by the pulse overlap, the substrate material and many other factors. A clear distinction must be made between the material ablation at the surface of a bulk material and the substrate selective removal of a thin metallic film. For the latter, general rules for the prediction of ablation results especially in the case of areal ablation, which were not known from the literature so far, are derived here in the form of mathematical criteria. A methodology for the parameter finding in different cases of ablation (dot, line, areal) is presented and exemplified using a practical example, but is also applicable to other flexible thin film based systems.

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“…Flexible foil-based sensor systems are ideally suited for integration or application to FRP materials [ 6 ]. Next to polyimide (PI) as a substrate material, which can be preferably processed in a liquid form for subsequent sensor microfabrication [ 7 , 8 , 9 ], other substrate materials like PEN and PET foil materials have been used for flexible electronics fabrication [ 10 ]. An overview of previous substrate choices and fabrication concepts has already been provided [ 11 ], where the importance of balancing material properties like thermal expansion, elastic moduli and adhesion strength for reliable operation of systems-in-foil under mechanical bending and at varied temperatures is outlined.…”

Section: Introductionmentioning

confidence: 99%

Smart Inlays for Simultaneous Crack Sensing and Arrest in Multifunctional Bondlines of Composites

Heide

Steinmetz

Schollerer

et al. 2021

Sensors

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Disbond arrest features combined with a structural health monitoring system for permanent bondline surveillance have the potential to significantly increase the safety of adhesive bonds in composite structures. A core requirement is that the integration of such features is achieved without causing weakening of the bondline. We present the design of a smart inlay equipped with a micro strain sensor-system fabricated on a polyvinyliden fluorid (PVDF) foil material. This material has proven disbond arrest functionality, but has not before been used as a substrate in lithographic micro sensor fabrication. Only with special pretreatment can it meet the requirements of thin film sensor elements regarding surface roughness and adhesion. Moreover, the sensor integration into composite material using a standard manufacturing procedure reveals that the smart inlays endure this process even though subjected to high temperatures, curing reactions and plasma treatment. Most critical is the substrate melting during curing when sensory function is preserved with a covering caul plate that stabilizes the fragile measuring grids. The smart inlays are tested by static mechanical loading, showing that they can be stretched far beyond critical elongations of composites before failure. The health monitoring function is verified by testing the specimens with integrated sensors in a cantilever bending setup. The results prove the feasibility of micro sensors detecting strain gradients on a disbond arresting substrate to form a so-called multifunctional bondline.

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Femtosecond laser-contoured micro-strain gages

Cited by 6 publications

References 12 publications

Niobium-Containing DLC Coatings on Various Substrates for Strain Gauges

Niobium-Containing DLC Coatings on Various Substrates for Strain Gauges

Methodology of selective metallic thin film ablation from susceptible polymer substrate using pulsed femtosecond laser

Smart Inlays for Simultaneous Crack Sensing and Arrest in Multifunctional Bondlines of Composites

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