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Mechanics and thermal management of stretchable inorganic electronics

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National Science Review 2016年第1期3卷 128-143页

作者： Jizhou Song Xue Feng yonggang huang Department of Engineering Mechanics and Soft Matter Research Center Zhejiang University Key Laboratory of Applied Mechanics Department of Engineering MechanicsTsinghua University Center for Mechanics and Materials Tsinghua University Department of Civil and Environmental Engineering Department of Mechanical EngineeringCenter for Engineering and Healthand Skin Disease Research CenterNorthwestern University

Stretchable electronics enables lots of novel applications ranging from wearable electronics, curvilinear electronics to bio-integrated therapeutic devices that are not possible through conventional electronics that is rigid and flat in nature. One effective strategy to realize stretchable electronics exploits the design of inorganic semiconductor material in a stretchable format on an elastomeric substrate. In this review, we summarize the advances in mechanics and thermal management of stretchable electronics based on inorganic semiconductor materials. The mechanics and thermal models are very helpful in understanding the underlying physics associated with these systems, and they also provide design guidelines for the development of stretchable inorganic electronics.

关键词： stretchable electronics buckling inorganic semiconductor material thin film

Non-uniform,axisymmetric misfit strain:in thin films bonded on plate substrates/substrate systems:the relation between non-uniform film stresses and system curvatures

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Acta Mechanica Sinica 2005年第4期21卷 362-370页

作者： yonggang huang D. Ngo A. J. Rosakis Department of Mechanical and Industrial Engineering University of Illinois Urbana at Urbana-Champain 1206 West Green Street IL 61801 USA Graduate Aeronautical Laboratory California Institute of TechnologyPasadena CA 91125 USA

Current methodologies used for the inference of thin film stress through curvature measurements are strictly restricted to stress and curvature states which are assumed to remain uniform over the entire film/substrate system. By considering a circular thin film/substrate system subject to non-uniform, but axisymmetric misfit strain distributions in the thin film, we derived relations between the film stresses and the misfit strain, and between the plate system＇s curvatures and the misfit strain. These relations feature a “local” part which involves a direct dependence of the stress or curvature components on the misfit strain at the same point, and a “non-local” part which reflects the effect of misfit strain of other points on the location of scrutiny. Most notably, we also derived relations between the polar components of the film stress and those of system curvatures which allow for the experimental inference of such stresses from full-field curvature measurements in the presence of arbitrary radial non-uniformities. These relations also feature a “non-local” dependence on curvatures making a full-field measurement a necessity. Finally, it is shown that the interfacial shear tractions between the film and the substrate are proportional to the radial gradients of the first curvature invariant and can also be inferred experimentally.

关键词： Non-uniform misfit strain Non-uniform wafer curvatures ,Stress-curvature relations Non-local effects ,Interfacial shears

CONCAVE BIOLOGICAL SURFACES FOR STRONG WET ADHESION

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Acta Mechanica Solida Sinica 2009年第6期22卷 593-604页

作者： Yewang Su Baohua Ji yonggang huang Kehchih Hwang Department of Engineering Mechanics Tsinghua University Beijing 100084 China Department of Applied Mechanics Beijing Institute of Technology Beijing 100081 China Department of Civil and Environmental Engineering Northwestern University Evanston IL 60208 USA

Plant leaves, insects and geckos are masters of adhesion or anti-adhesion by smartly designed refined surface structures with micro- and nano- ＇technologies＇. Understanding the basic principles in the design of the unique surface structures is of great importance in the manufacture or synthesis of micro- and nano- devices in MEMS or NEMS. This study is right inspired by this effort, focusing on the mechanics of wet adhesion between fibers having concave tips and a flat substrate via capillary forces. We show that the concave surface can effectively enhance the wet adhesion by reducing the effective contact angle of the fiber, firmly pinning the liquid bridge at its circumferential edge. A critical contact angle is identified below which the adhesion strength can achieve its maximum, being insensitive to the contact angle between the fiber and liquid. The analytical expression for the critical angle is derived. Then a tentative design for the profile of concave surfaces is proposed, considering the effects of chamfering size, deformation and buckling, etc. The effect of liquid volume on the wet adhesion of multiple-fiber system is also discussed.

关键词： biological surface wet adhesion contact shape concave surface robustness ad- hesion force

The indenter tip radius effect in micro- and nanoindentation hardness experiments

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Acta Mechanica Sinica 2006年第1期22卷 1-8页

作者： Fan Zhang yonggang huang Keh-Chih Hwang FML Department of Engineering MechanicsTsinghua University Beijing 100084 China Dept. of Mechanical and Industrial Engineering University of Illinois Urbana IL 61801 USA

Nix and Gao established an important relation between the microindentation hardness and indentation depth. Such a relation has been verified by many microindentation experiments （indentation depths in the micrometer range）, but it does not always hold in nanoindentation experiments （indentation depths approaching the nanometer range）. Indenter tip radius effect has been proposed by Qu et al. and others as possibly the main factor that causes the deviation from Nix and Gao＇s relationship. We have developed an indentation model for micro- and nanoindentation, which accounts for two indenter shapes, a sharp, conical indenter and a conical indenter with a spherical tip. The analysis is based on the conventional theory of mechanism-based strain gradient plasticity established from the Taylor dislocation model to account for the effect of geometrically necessary dislocations. The comparison between numerical result and Feng and Nix＇s experimental data shows that the indenter tip radius effect indeed causes the deviation from Nix-Gao relation, but it seems not be the main factor.

关键词： Taylor dislocation model Strain gradient plasticity Indentation Nix-Gao relation

Dynamic and steady control of quantum coherence in photonic crystals via the Zeeman effect

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Science China(Physics,Mechanics & Astronomy) 2012年第12期55卷 2300-2304页

作者： CHEN LuZhou huang yonggang JIN ChongJun WANG XueHua State Key Laboratory of Optoelectronic Materials and Technologies School of Physics and EngineeringSun Yat-Sen UniversityGuang zhou 510275China

The dynamic evolution of a multi-level atom in the three-dimensional photonic crystal under an applied magnetic field is *** combining the Zeeman effect with the photonic band gap effect,the dynamic quantum superposition states and steady quantum coherent trapping states of the atom can be flexibly *** paves the way for coherent manipulation of quantum states in the solid-state system,which has important applications in quantum information processing.

关键词： quantum superposition state control of quantum coherence photonic crystal gap Zeeman effect

Analytical Modeling of Flowrate and Its Maxima in Electrochemical Bioelectronics with Drug Delivery Capabilities

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Research 2022年第3期2022卷 61-73页

作者： Raudel Avila Yixin Wu Rinaldo Garziera John A.Rogers yonggang huang Department of Mechanical Engineering Northwestern UniversityEvanstonIL 60208USA Department of Materials Science and Engineering Northwestern UniversityEvanstonIL 60208USA Querrey Simpson Institute for Bioelectronics Northwestern UniversityEvanstonIL 60208USA Dipartimento di Ingegneria ed Architettura Universitàdi ParmaItaly Department of Biomedical Engineering Northwestern UniversityEvanstonIL 60208USA Department of Electrical and Computer Engineering Northwestern UniversityEvanstonIL 60208USA Department of Chemistry Northwestern UniversityEvanstonIL 60208USA Department of Neurological Surgery Northwestern UniversityFeinberg School of MedicineChicagoIL 60611USA Department of Civil and Environmental Engineering Northwestern UniversityEvanstonIL 60208USA

Flowrate control in flexible bioelectronics with targeted drug delivery capabilities is essential to ensure timely and safe *** neuroscience and pharmacogenetics studies in small animals,these flexible bioelectronic systems can be tailored to deliver small drug volumes on a controlled fashion without damaging surrounding tissues from stresses induced by excessively high *** drug delivery process is realized by an electrochemical reaction that pressurizes the internal bioelectronic chambers to deform a flexible polymer membrane that pumps the drug through a network of microchannels implanted in the small *** flowrate temporal profile and global maximum are governed and can be modeled by the ideal gas ***,we obtain an analytical solution that groups the relevant mechanical,fluidic,environmental,and electrochemical terms involved in the drug delivery process into a set of three nondimensional *** unique combinations of these three nondimensional parameters(related to the initial pressure,initial gas volume,and microfluidic resistance)can be used to model the flowrate and scale up the flexible bioelectronic design for experiments in medium and large animal *** analytical solution is divided into(1)a fast variable that controls the maximum flowrate and(2)a slow variable that models the temporal ***,the two variables detail the complete drug delivery process and control using the three nondimensional *** of the analytical model with alternative numerical models shows excellent agreement and validates the analytic modeling *** findings serve as a theoretical framework to design and optimize future flexible bioelectronic systems used in biomedical research,or related medical fields,and analytically control the flowrate and its global maximum for successful drug delivery.

关键词： governed Electrochemical Flow

Flexible electronics with dynamic interfaces for biomedical monitoring,stimulation,and characterization

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International Journal of Mechanical System Dynamics 2021年第1期1卷 52-70页

作者： Xu Guo Raudel Avila yonggang huang Zhaoqian Xie State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsDalian University of TechnologyDalianChina Ningbo Institute of Dalian University of Technology NingboChina Department of Mechanical Engineering Northwestern UniversityEvanstonIllinoisUSA Departments of Civil and Environmental Engineering Northwestern UniversityEvanstonIllinoisUSA Departments of Materials Science and Engineering Northwestern UniversityEvanstonIllinoisUSA Center for Bio‐integrated Electronics Northwestern UniversityEvanstonIllinoisUSA

Recent developments in the fields of materials science and engineering technology(mechanical,electrical,biomedical)lay the foundation to design flexible bioelec-tronics with dynamic interfaces,widely used in biomedical/clinical monitoring,stimulation,and *** of this technology include body motion and physiological signal monitoring through soft wearable devices,mechanical characterization of biological tissues,skin stimulation using dynamic actuators,and energy harvesting in biomedical ***,these bioelectronic systems feature thin form factors for enhanced flexibility and soft elastomeric encapsula-tions that provide skin‐compliant mechanics for seamless integration with biological *** review examines the rapid and continuous progress of bioelectronics in the context of design strategies including materials,mechanics,and structure to achieve high performance dynamic interfaces in *** concludes with a concise summary and insights into the ongoing opportunities and challenges facing developments of bioelectronics with dynamic interfaces for future applications.

关键词： energy harvesters flexible and stretchable electronics health monitors vibration dynamics wearable devices

IJMSD: A novel journal devoting to promote the progress of modern science, technology and industry by enhancing the capabilities of mechanical system dynamics

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International Journal of Mechanical System Dynamics 2021年第1期1卷 3-4页

作者： Xiaoting Rui Marco Amabili Peter Eberhard yonggang huang Nanjing University of Science and Technology NanjingChina McGill University MontrealCanada University of Stuttgart StuttgartGermany Northwestern University EvanstonUSA

From the Stone Age to modern industry,the development of me-chanical systems has driven human civilization and the progress of science and *** dynamic performances related to manufacturing precision,mobility,comfort,reliability,and safety have become the bottlenecks restricting the development of con-temporary industrial products,which can be regarded as complex and integrated mechatronical systems composed of many subsystems with highly coupled dynamical *** the advent of the fourth industrial revolution and the widely used complicated and integrated products,it has been found clearly that quasi‐static or local dynamics study can no longer capture the critical features of contemporary mechanical systems.

关键词： dynamics journal restrict

A NUMERICAL STUDY OF INDENTATION WITH SMALL SPHERICAL INDENTERS

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Acta Mechanica Solida Sinica 2009年第1期22卷 18-26页

作者： Jiang Qin Shaoxing Qu Xue Feng yonggang huang Jianliang Xiao Keh-Chih Hwang Department of Engineering Mechanics Tsinghua University Beijing 100084 China Department of Mechanics Zhejiang University Hangzhou 310027 China Department of Civil and Environmental Engineering Northwestern University Evanston IL 60208 USA Department of Mechanical Engineering Northwestern University Evanston IL 60208 USA

The finite element method for the conventional theory of mechanism-based strain gradient plasticity is used to study the indentation size effect. For small indenters （e.g., radii on the order of 10μm）, the maximum allowable geometrically necessary dislocation （GND） density is introduced to cap the GND density such that the latter does not become unrealistically high. The numerical results agree well with the indentation hardness data of iridium. The GND density is much larger than the density of statistically stored dislocations （SSD） underneath the indenter, but this trend reverses away from the indenter. As the indentation depth （or equivalently, contact radius） increases, the GND density decreases but the SSD density increases.

关键词： indentation size effect spherical indenters geometrically necessary dislocations,maximum density