Vladimir Kolchuzhin

The substrate matters in the Raman spectroscopy analysis of cells

Raman spectroscopy is a powerful analytical method that allows deposited and/or immobilized cells to be evaluated without complex sample preparation or labeling. However, a main limitation of Raman spectroscopy in cell analysis is the extremely weak Raman intensity that results in low signal to noise ratios. Therefore, it is important to seize any opportunity that increases the intensity of the Raman signal and to understand whether and how the signal enhancement changes with respect to the substrate used. Our experimental results show clear differences in the spectroscopic response from cells on different surfaces. This result is partly due to the difference in spatial distribution of electric field at the substrate/cell interface as shown by numerical simulations. We found that the substrate also changes the spatial location of maximum field enhancement around the cells. Moreover, beyond conventional flat surfaces, we introduce an efficient nanostructured silver substrate that largely enhances the Raman signal intensity from a single yeast cell. This work contributes to the field of vibrational spectroscopy analysis by providing a fresh look at the significance of the substrate for Raman investigations in cell research.

Parametric model extraction for MEMS based on variational finite element techniques

This article is focused on new finite element technologies which account for parameter variations in a single finite element run. The key idea of the new approach is to compute not only the governing system matrices of the FE problem but also n high order partial derivatives with regard to design parameters by means of automatic differentiation (AD). As result, Taylor vectors of the systems response can be expanded in the vicinity of the initial position capturing dimensions and physical parameter. Essential speed-up can be achieved for shape optimization, sensitivity analyses and data sampling needed for reduced order modeling of MEMS.

A derivatives-based method for parameterization of MEMS Reduced Order Models

The paper demonstrates an advanced simulation methodology based on differentiation of the discretized Finite Element (FE) equations for parameterization of MEMS macromodels. The idea of the approach is to compute not only the governing system matrices but also high order derivatives (HOD) with regard to design parameters by means of Automatic Differentiation (AD). As result, Taylor vectors of the model response can be expanded in the vicinity of the initial position with regard to dimensional and physical parameters. The objective of this presentation is to demonstrate the viability of HOD methods to parameterization of the mode superposition based Reduced Order Models (ROM) of the coupled- physics domains.

Application of Higher Order Derivatives Method to Parametric Simulation of MEMS

The paper demonstrates the advanced simulation methodology based on differentiation of the discretized finite element (FE) equations to parametric simulation of micro-electro-mechanical-systems (MEMS). The idea of the approach is to compute not only the governing system matrices but also high order derivatives (HOD) with regard to design parameters by means of automatic differentiation (AD). As result, Taylor vectors of the model response can be expanded in the vicinity of the initial position with regard to dimensional and physical parameters. The objective of this presentation is to demonstrate the viability of HOD methods to parametric simulation of MEMS in the static, modal, frequency response domains on the basis of the structural analysis and macromodeling.

Recent developments in reduced order modeling based on mode superposition technique

The paper is focused on advanced reduced order modeling (ROM) methods for MEMS using mode superposition technique and finite element solvers for data extraction for the governing equations. Dynamically accurate behavior representations can be achieved for microstructures with flexible components and their most important interactions with thermal, electrostatic and fluid fields. Results are macromodel based on analytical terms which can be transferred to electronic and system simulators for virtual prototyping and device analyses.

Parametric Finite Element Analysis for Reduced Order Modeling of MEMS

In this paper we describe a simulation methodology based on FEM to automatic generating reduced order models of coupled microelectro-mechanical systems (MEMS). In particular, the time consuming FE data sampling process should be replaced by a single finite element run. The idea of the new approach is to compute not only the governing system matrices but also high order partial derivatives with regard to design parameters by means of automatic differentiation. As result, Taylor vectors of the model response can be expanded in the vicinity of the initial position with regard to dimensional and physical parameters. The approach is demonstrated on example of a micromirror cell

The influence of packaging technologies on the performance of inertial MEMS sensors

The paper is focused on the influence of packaging technologies on the performance of inertial MEMS sensors. System simulations of MEMS are vital to evaluate and optimize the interplay of transducer cells with the sensor electronics. Special emphasis must be put on packaging aspects in order to assess the impact of environmental and operating conditions on functional parameters as capacitance offset or loss of sensitivity affected by thermal-mechanical stress or structural deformation. This article presents modern reduced order modeling technologies which extract fast and accurate behavioral models from a series of finite element runs which can directly be used in Matlab/Simulink or Verilog-A for system design.

Challenges in MEMS parametric macro-modeling based on mode superposition technique

Computational approaches, opportunities and challenges in reduced order modelling based on mode superposition method of the coupled electrostatic-structural domains, including effective model generation and geometrical parameterization, as well as physical and system design of MEMS component are presented and discussed.

An optimization of initial gap in electrostatic comb drive

An optimization of initial gap of a movable electrode in elementary cell of planar electrostatic comb drive utilized transverse displacement is considered and analyzed. An analytical equation providing the maximal value of relation between sensitivity and area of the elementary cell is obtained in one-dimensional case.

Piezoresistance of Single Walled Carbon Nanotube in VHDL-AMS

Ver.1.0 07.03.2015 This tutorial deals with the model development of the piezoresistance of Single Walled Carbon Nanotubes (SWCNTs) as components at system level design. The framework VHDL-AMS (virtual hardware description language) is used for implementation and simulation. It is based on compact models to describe the components performing heterogeneous functions. The mechanical and electronical compact submodels of SWCNTs are based on the analytical models and lumped element models. The tutorial presents important aspects in developing these system models and the necessary parameters in creating those models. The developed models can be used for the design of SWCNT based mechanical sensors and for co-simulation with any other system environment or complex electronic circuit.