Ghader Rezazadeh

Current Researchs

MEMS Capacitive Structures: Modeling Soft Dielectric Materials for Enhanced Performance
One emerging strategy for improving device performance in Micro-Electro-Mechanical Systems (MEMS) is the use of soft dielectric materials as gap fillers in capacitive devices. This method involves investigating the dynamic behavior of capacitive devices, considering the complex nature of soft materials using several constitutive models.
The research examines constitutive models, including traditional Hookean models and more complex models such as Neo-Hookean, Ogden, and Super-elastic models. Understanding the complex mechanical behavior of capacitive structures, such as beam or plate configurations, supported by soft dielectric materials is critical. The proposed method utilizes coupled models that consider the inertia and damping characteristics of the soft dielectric material, as opposed to basic nonlinear spring models.
The porosity of soft dielectric materials can be adjusted to fine-tune their dielectric constant and Young’s modulus. Therefore, a displacement-dependent porosity element is added to the dynamic model to account for the porosity of the soft material. The coupled equations become even more complex when this factor is combined with the nonlinearity caused by the electrostatic force and mid-plane stretching.
The model accurately represents the real behavior of the capacitive structure by capturing the nonlinear interaction among its components. The study analyzes the steady-state responses, dynamic transient responses, and static behavior of MEMS capacitive structures. The problem’s nonlinearity presents difficulties, but it also invites creative solutions that can improve MEMS device performance and design.
The study’s findings have the potential to revolutionize the field of MEMS technology by enabling breakthroughs that are not limited by traditional design paradigms. The emerging frontier in MEMS technology is focused on understanding the intricacies of soft dielectric materials and their interaction with capacitive structures. This area of research is expected to result in improved efficiency and versatility across various technological disciplines.

Thermomechanical Modeling of Human Tissues under Laser Irradiation for Diverse Applications (In Collaboration with Institute of Structural Mechanics and Dynamics in Aerospace Engineering, University of Stuttgart)

Thermomechanical modeling of laser-irradiated human tissues is a rapidly emerging topic with numerous medical research implications. This analysis considers the inherent variety of human tissues, including factors such as density, color, and Young’s modulus. The simulation includes the laser absorption coefficient and introduces a novel twist by using nanoparticles to accelerate and localize temperature increases in specific tissue regions.
The addition of nanoparticles to laser radiation improves localized temperature and serves as a catalyst for pinpoint accuracy. The precise regulation and modification of temperature at the microscopic level is critical for several applications, including tissue healing, cancer ablation, and collagen stimulation for rejuvenation. This creates opportunities for customized medicinal interventions that are changing the field of therapeutic approaches.
Thermomechanical modeling provides valuable insights into the responses of human tissues to laser irradiation. This knowledge is particularly important for applications such as cosmetic treatments, where precise control of collagen stimulation is necessary for rejuvenation. Similar to this, the modeling process has the ability to promote localized temperature increases in cancer ablations, offering hope for focused and efficient treatment that minimizes collateral damage to nearby healthy tissues.
The range of potential applications for thermomechanical modeling is growing as research in the subject progresses, offering creative solutions to many medical problems. The method’s accuracy enhances the effectiveness of available treatments and stimulates the creation of new therapeutic approaches. The combination of thermomechanical modeling, laser irradiation, and nanoparticle-enhanced precision has the potential to transform medicine, resulting in better patient outcomes and more effective interventions.

Dynamic Modeling of Shelled Microbubbles and Exploring Secondary Resonances in Medical Imaging Contrast Enhancement
The study of shelled microbubbles and the application of nonlinear dynamic modeling to it are at the forefront of a revolution in medical imaging. Protein, lipid, and other shell-encased microbubbles have become indispensable for improving contrast in imaging, particularly when used as contrast agents in sophisticated procedures like contrast-enhanced ultrasonography (CEUS).
These shelled bubbles have naturally nonlinear dynamic behavior. This investigation makes use of nonlinear dynamic modeling, a method that lets us comprehend and forecast the behavior of systems that go beyond simple cause-and-effect interactions. We examine the complex interactions and oscillations of shelled microbubbles in the presence of ultrasonic waves using this modeling approach. The nonlinear dynamics of microbubbles introduce complicated and intricate behavior, in contrast to linear systems where the response is exactly proportional to the input.
A significant component of this research involves the examination of both primary and secondary resonances. Resonance, which raises a system’s reactivity as it vibrates at its inherent frequency, assumes additional meaning in the context of microbubbles. Secondary resonances reflect additional frequencies at which these bubbles vary, providing a wealth of information beyond the reach of conventional imaging tools. Understanding and utilizing these secondary resonances may create new opportunities for contrast imaging, enabling more nuanced and in-depth examinations of tissues and structures.
Imaging techniques can be greatly improved by including nonlinear dynamic modeling into the investigation of shelled microbubbles. Researchers can adjust imaging procedures, improve contrast enhancement, and investigate applications in targeted medication delivery by understanding the complex dynamics of these bubbles. This integrative approach opens the door to new developments in medical diagnostics and therapies while also advancing our grasp of the physics driving microbubble behavior.
Essentially, the combination of shelled microbubbles and nonlinear dynamics opens up new possibilities for medical imaging by helping to understand the nuances of bubble behavior and improving our capacity to see and understand the human body with never-before-seen clarity.

Collaboration on the research project titled ‘Design and Fabrication of a MEMS Mass Sensor for the Detection of Biomarkers of Liver Cancer‘ is currently being conducted at Swansea University.
Mass spectrometry is essential for identifying species and compounds, but it is not suitable for biomasses, which are in the Giga-daltons (GDa) range. Nano/Micro electro mechanical resonators have been used for biomass sensing, but challenges remain, such as high frequency resonators, position dependency, and the effects of biomass properties on sensor accuracy. Micro cantilever bio sensing faces challenges in liquid environments, viscous damping, and dissipative inertia forces.
In the current research project a novel MEMS sensor for mass detection of cancer biomarkers, specifically AFP biomarker for early-stage liver cancer diagnosis, is proposed. The electro-mechanical sensor architecture consists of a free-standing central disk suspended by beam elements excited by an electrostatic comb drive. The key advantages of this architecture over traditional cantilever beam-based mass sensor design are that the output is independent of the biomarker’s position and that the added receptor and biomarker remain unchanged in the structure.

2024

• M Asadi, G Rezazadeh, V Sinitsin; Exploring Gradual Material Rigidity Degradation Effects on the Nonlinear Coupled Axial-Transversal Nonlinear Response of a Capacitive Micro-Beam, European Journal of Mechanics / A Solids

• Ahmad Hasheem Kareem, Mohammad Fathalilou, Ghader Rezazadeh; Mathematical Modeling of an Electrostatic MEMS with Tilted Elastomeric Micro-pillars, Applied Mathematical Modelling

• S Valizadeh, M Fathalilou, G Rezazadeh, Effects of the temperature-dependent behavior of the gap filling Pdms on the response of a capacitive mems to the electrostatic actuation, International Journal of Applied Mechanics

• SM Seyedpour, M Azhdari, L Lambers, T Ricken, G Rezazadeh, One-dimensional thermomechanical bio-heating analysis of viscoelastic tissue to laser radiation shapes, International Journal of Heat and Mass Transfer, Volume 218, January 2024, 124747

• M. Ghanbari, G. Rezazadeh, V. Molodpour , A Wide-bandwidth MEMS Energy Harvester Based on a Novel Voltage-Sliding Stiffness Tunability, Applied Mathematical Modeling, Volume 125, Part A, 2024, Pages 16-34

2023
• S. Motaei, M. Ghazavi, G. Rezazadeh, Incorporating Temperature-Dependent Properties into the Modeling of Photo-Thermo-Mechanical Interactions in Cancer Tissues.  Thermal Science and Engineering Progress; 2023
• Mohammad Azhdari, Seyed Morteza Seyedpour, Hans-Michael Tautenhahn, Franziska Tautenhahn, Tim Rickenb, Ghader Rezazadeh , Non-local Three Phase Lag Bio Thermal Modeling of Skin Tissue and Experimental Evaluation, International Communications in Heat and Mass Transfer, Volume 149, December 2023, 107146
• K Soltani, SM Seyedpour, T Ricken, G Rezazadeh, Transient High-Frequency Spherical Wave Propagation in Porous Medium using Fractional Calculus Technique, Acta Mechanica, 2023
• SM Seyedpour, L Lambers, T Ricken, G Rezazadeh, Mathematical modelling of the dynamic response of an implantable enhanced capacitive glaucoma pressure sensorMeasurement: Sensors; Volume 30, December 2023, 100936
• M Azhdari, SM Seyedpour, T Rickenb, G Rezazadeh, On the Thermo-Vibrational Response of Multi-Layer Viscoelastic Skin Tissue to Laser Irradiation  , International Journal of Thermal Sciences, Volume 187, May 2023, 108160
• M Ghanbari, G Rezazadeh, V Moloupor-Toulkani, M Sheykhlou, Dynamic Analysis of a Novel Wide-Tunable Microbeam Resonator with a Sliding Free-of-Charge Electrode, Nonlinear Dynamics, 111, pages8039–8060 (2023)
• S Dindar, S Afrang, G Rezazadeh, On the selective mode excitation of wide tunable MEMS capacitive resonator, Microsystem Technologies, 2023, volume 29, pages1703–1713 (2023)
• K Soltani, G Rezazadeh, MP Henry, Nonlinear Dynamics of a Broadband Vortex-Induced Vibration based Energy Harvester, Journal of Engineering Mechanics, Volume 149, Issue 8, 202
• R Rahimi, G Rezazadeh, M Asadi, Nonlinear dynamic modeling of a micro-plate resonator considering damage accumulation, Acta Mechanica, 2023, 234, pages2933–2946 (2023)
• M Ghanbari, G Rezazadeh, V Moloupor-Toulkani, Nonlinear Dynamics of a Tunable Novel Accelerometer, Tunable with a Micro Triple Electrode Variable Capacitor , Acta Mechanica, 234, pages3197–3218 (2023)
• M Tofigh, A Shah-Mohammadi-Azar, G Rezazadeh, M Mahjoob, Fractional-Order Sliding Mode Control for a Novel Magneto-Electro-Elastic Microtube Robot, Asian Journal of Control, Volume 25, Issue 6 p. 4159-4170
• S Valizadeh, M Fathalilou, G Rezazadeh, Material dielectricity effects on the performance of capacitive micro-devices; a nonlinear study, International Journal of Mechanics and Materials in Design, 19, pages537–552 (2023)
• K Soltani, M Fathalilou, G Rezazadeh, DEVELOPMENT OF AN ELECTROSTAYICLLY ACTUATED FLOWRATE CONTROLLER: MODELLING AND CHARACTERIZATION, International Journal of Applied Mechanics, Vol. 15, No. 02, 2350008 (2023)

For publications prior to 2023, please refer to the provided links, such as: https://orcid.org/0000-0001-5243-3199

• Instrumentation
• Sensors and Actuators
• Resonators and Filters
• Smart Materials
• Energy Harvesters
• Bifurcation and Static and Dynamic Stability of Mechanical Systems
• Modeling of MEMS/NEMS Structures and Bio-MEMS
• Heat-Induced Vibrations
• Thermo-Elastic and Squeeze Film Damping
• Non-Fourier Heat Conduction Models
• Mechanical Vibration and Nonlinear Vibration
• Dynamics and Nonlinear Dynamics
• Higher-order, Higher gradient, and Nonlocal Theories of Continuum Media
• Fluid Solid Interaction Problems,
• Acoustic, Photoacoustic, and Thermo-Acoustic,
• Thermal Induced Vibration in Tissue,
• Bubble dynamics,
• Wave Propagation in Porous Media,
• Hydrogels,
• Aerogels,
• Scale Dependent Behavior of Structures,
• A New perspective on continuity,
• Scale Dependent Calculus
• General Theory of Nonlocality
• Numerical Methods, Proper Orthogonal Decomposition Reduced Order Models, or Galerkin Based Reduced Order Models.

• Appointed as a Distinguished Professor by the Iranian Society of Mechanical Engineers (ISME),
• Appointed as a Distinguished Researcher by Urmia University,
• Listed as the top 1% highly cited researchers in 2017, 2019, and 2020.

• Mohammad Azhdari
• Anna Kasheva
• Mohammad Asadi
• Araz Feyzi

• Continuum Mechanics
• Mechanical Vibrations
• Mechanical Vibration of Continuous Systems
• Nonlinear Vibrations
• Solid Mechanics