Adhesion Asymmetry in Peeling of Thin Films With Homogeneous Material Properties: A Geometry-Inspired Design Paradigm

2019 ◽  
Vol 86 (7) ◽  
Author(s):  
Ahmed Ghareeb ◽  
Ahmed Elbanna
Keyword(s):  
Thin Films ◽  
Material Properties ◽  
Homogeneous Material ◽  
Film Material ◽  
Adhesive Material ◽  
Element Analysis ◽  
Nonuniform Thickness ◽  
Design Paradigm ◽  
Scientists And Engineers ◽  
Compositional Properties

Peeling of thin films is a problem of great interest to scientists and engineers. Here, we study the peeling response of thin films with nonuniform thickness profile attached to a rigid substrate through a planar homogeneous interface. We show both analytically and using finite element analysis that patterning the film thickness may lead to direction-dependent adhesion such that the force required to peel the film in one direction is different from the force required in the other direction, without any change to the film material, the substrate interfacial geometry, or the adhesive material properties. Furthermore, we show that this asymmetry is tunable through modifying the geometric characteristics of the thin film to obtain higher asymmetry ratios than reported previously in the literature. We discuss our findings in the broader context of enhancing interfacial response by modulating the bulk geometric or compositional properties.

The Effect of Inorganic Thin Film Material Processing and Properties on Stress in Silicon Piezoresistive Pressure Sensors

1996 ◽  
Vol 444 ◽  
Author(s):  
G. Bitko ◽  
A. C. McNeil ◽  
D. J. Monk
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Pressure Sensors ◽  
Film Material ◽  
Element Analysis ◽  
Silicon Nitride Films ◽  
Silicon Bulk ◽  
Inorganic Thin Films ◽  
Piezoresistive Pressure Sensors ◽  
Thin Film Patterning

AbstractSilicon bulk micromachined piezoresistive pressure sensors are sensitive to stresses caused by the application of inorganic thin films typically used for passivation purposes, and the change in stress that is caused by temperature changes in the operating environment of the sensor. Stress behavior over temperature is characterized for both thermal oxides grown on silicon at thicknesses from 0.18 μm to 0.36 μm, and PECVD silicon nitride films at thicknesses from 0.40 μm to 0.80 μn. Electrical parametric behavior is characterized for typical piezoresistive pressure sensors with these thin films deposited and patterned in several proposed passivation schemes. A finite element analysis is performed to predict how device parameters vary as a function of thin film patterning and properties. Correlations are drawn between model predictions, independent thin film behavior, and device performance.

On-Chip Structures for the Determination of the Dopant-Dependent Young’s Modulus of Heavily Phosphorus Doped Polysilicon With Stress Compensation

2010 ◽  
Author(s):  
E. Bassiachvili ◽  
J. R. Godin ◽  
P. Nieva ◽  
A. Khajepour
Keyword(s):  
Thin Films ◽  
Young’S Modulus ◽  
Material Properties ◽  
Young's Modulus ◽  
Direct Access ◽  
Film Material ◽  
Heavily Doped ◽  
Stress Compensation ◽  
On Chip

Accurate knowledge of thin-film material properties, such as Young’s modulus, is imperative in proper design and operation of MEMS devices. The use of on-chip devices allows direct access to the material properties as they are known to change with fabrication process, temperature as well as location within the wafer. Resonant and pull-in structures have been designed and modeled for the measurement of the Young’s modulus of heavily doped polysilicon thin films. The cantilever and clamped-clamped beams allow us to extract the Young’s modulus through observing the resonant frequency and pull-in voltage and cross-referencing the results. Mechanical actuation using a calibrated piezoelectric shaker for some devices and electrostatic actuation for others ensures that the structural effects, rather than the actuation technique, are responsible for the varying response at different temperatures. Optical readout will be used in order to reduce readout-associated errors, which can occur with purely electrical techniques at higher temperatures. However, electrical readout is also possible for some of the devices. The devices have been designed and fabricated using a customized 1-mask process. In this paper, we present the modeling and numerical simulations obtained for heavily doped polysilicon microstructures and will describe the method used for the determination of the Young’s modulus with stress compensation. Although the method described here has been used for heavily doped polysilicon thin films, it can be easily modified for the determination of Young’s modulus of other MEMS structural materials.

scholarly journals Impact of residual stress evoked by pyramidal embossing on the magnetic material properties of non-oriented electrical steel

2021 ◽  
Author(s):  
Ines Gilch ◽  
Tobias Neuwirth ◽  
Benedikt Schauerte ◽  
Nora Leuning ◽  
Simon Sebold ◽  
...  
Keyword(s):  
Magnetic Material ◽  
Residual Stress ◽  
Magnetic Flux ◽  
Material Properties ◽  
Electrical Steel ◽  
Maximum Energy ◽  
Material Behavior ◽  
Electrical Machine ◽  
Element Analysis ◽  
Steel Sheets

AbstractTargeted magnetic flux guidance in the rotor cross section of rotational electrical machines is crucial for the machine’s efficiency. Cutouts in the electrical steel sheets are integrated in the rotor sheets for magnetic flux guidance. These cutouts create thin structures in the rotor sheets which limit the maximum achievable rotational speed under centrifugal forces and the maximum energy density of the rotating electrical machine. In this paper, embossing-induced residual stress, employing the magneto-mechanical Villari effect, is studied as an innovative and alternative flux barrier design with negligible mechanical material deterioration. The overall objective is to replace cutouts by embossings, increasing the mechanical strength of the rotor. The identification of suitable embossing geometries, distributions and methodologies for the local introduction of residual stress is a major challenge. This paper examines finely distributed pyramidal embossings and their effect on the magnetic material behavior. The study is based on simulation and measurements of specimen with a single line of twenty embossing points performed with different punch forces. The magnetic material behavior is analyzed using neutron grating interferometry and a single sheet tester. Numerical examinations using finite element analysis and microhardness measurements provide a more detailed understanding of the interaction of residual stress distribution and magnetic material properties. The results reveal that residual stress induced by embossing affects magnetic material properties. Process parameters can be applied to adjust the magnetic material deterioration and the effect of magnetic flux guidance.

Size- and temperature-dependent Young's modulus and size-dependent thermal expansion coefficient of thin films

2016 ◽  
Vol 18 (31) ◽  
pp. 21508-21517 ◽  
Author(s):  
Xiao-Ye Zhou ◽  
Bao-Ling Huang ◽  
Tong-Yi Zhang
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Young’S Modulus ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Material Properties ◽  
Essential Role ◽  
Young's Modulus ◽  
Temperature Dependent ◽  
Size Dependent

Surfaces of nanomaterials play an essential role in size-dependent material properties.

scholarly journals On the Design of a Biodegradable POC-HA Polymeric Cardiovascular Stent

2012 ◽  
Author(s):  
Joonas Ponkala ◽  
Mohsin Rizwan ◽  
Panos S. Shiakolas
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Properties ◽  
Three Dimensional ◽  
Polymeric Composite ◽  
Coronary Stent ◽  
Element Analysis ◽  
Material Models ◽  
Solid Models ◽  
Biodegradable Stents

The current state of the art in coronary stent technology, tubular structures used to keep the lumen open, is mainly populated by metallic stents coated with certain drugs to increase biocompatibility, even though experimental biodegradable stents have appeared in the horizon. Biodegradable polymeric stent design necessitates accurate characterization of time dependent polymer material properties and mechanical behavior for analysis and optimization. This manuscript presents the process for evaluating material properties for biodegradable biocompatible polymeric composite poly(diol citrate) hydroxyapatite (POC-HA), approaches for identifying material models and three dimensional solid models for finite element analysis and fabrication of a stent. The developed material models were utilized in a nonlinear finite element analysis to evaluate the suitability of the POC-HA material for coronary stent application. In addition, the advantages of using femtosecond laser machining to fabricate the POC-HA stent are discussed showing a machined stent. The methodology presented with additional steps can be applied in the development of a biocompatible and biodegradable polymeric stents.

The Optical Properties of Thin Films Tin Oxide with Triple Doping (Aluminum, Indium, and Fluorine) for Electronic Device

2021 ◽  
Vol 317 ◽  
pp. 477-482
Author(s):  
Aris Doyan ◽  
Susilawati ◽  
Muhammad Taufik ◽  
Syamsul Hakim ◽  
Lalu Muliyadi
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Activation Energy ◽  
Optical Properties ◽  
Tin Oxide ◽  
Electronic Device ◽  
Film Material ◽  
Mass Percentage ◽  
Gap Energy ◽  
As Doping

Tin oxide (SnO2) thin film is a form of modification of semiconductor material in nanosize. The thin film study aims to analyze the effect of triple doping (Aluminum, Indium, and Fluorine) on the optical properties of SnO2: (Al + In + F) thin films. Aluminum, Indium, and Fluorine as doping SnO2 with a mass percentage of 0, 5, 10, 15, 20, and 25% of the total thin-film material. The addition of Al, In, and F doping causes the thin film to change optical properties, namely the transmittance and absorbance values ​​changing. The transmittance value is 67.50, 73.00, 82.30, 87.30, 94.6, and 99.80 which is at a wavelength of 350 nm for the lowest to the highest doping percentage, respectively. The absorbance value increased with increasing doping percentage at 300 nm wavelength of 0.52, 0.76, 0.97, 1.05, 1.23, and 1.29 for 0, 5, 10, 15, 20, and 25% doping percentages, respectively. The absorbance value is then used to find the gap energy of the SnO2: (Al + In + F) thin film of the lowest doping percentage to the highest level i.e. 3.60, 3.55, 3.51, 3.47, 3.42, and 3.41 eV. Thin-film activation energy also decreased with values of 2.27, 2.04, 1.85, 1.78, 1.72, and 1.51 eV, respectively for an increasing percentage of doping. The thin-film SnO2: (Al + In + F) which experiences a gap energy reduction and activation energy makes the thin film more conductive because electron mobility from the valence band to the conduction band requires less energy and faster electron movement as a result of the addition of doping.

Contact stiffness depth-sensing indentation: Understanding of material properties of thin films attached to substrates

2017 ◽  
Vol 114 ◽  
pp. 172-179 ◽  
Author(s):  
Ivan I. Argatov ◽  
Feodor M. Borodich ◽  
Svetlana A. Epshtein ◽  
Elena L. Kossovich
Keyword(s):  
Thin Films ◽  
Material Properties ◽  
Contact Stiffness ◽  
Depth Sensing
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