Modelling package turns to MEMS design

A new MEMS Module for the Femlab mathematical modelling package allows designers to model micro electromechanical systems with physical dimensions of microns.

One of the most exciting areas of technology to emerge in recent years is MEMS (micro electromechanical systems), where engineers design and build systems with physical dimensions of microns.

With the release of a MEMS Module for the Femlab mathematical modelling package, Comsol offers a tool it reckons is unsurpassed by anything on the market, one that allows scientists and engineers to exploit this high-growth field.

The new module is especially powerful because virtually all MEMS devices involve the coupling of multiple physics phenomena, known as multiphysics, an area where Femlab excels.

The MEMS Module works as an addon to the core Femlab package, which itself is an advanced tool for modelling and simulating any physical process that can be described with partial differential equations (PDEs).

It comes with a sophisticated CAD editor and high-performance state-of-the-art solvers that address extremely large problems yet quickly yield accurate results.

Working in an easy-to-use graphical interface, users choose from several ways to describe their problems in 1D, 2D and 3D.

A strength of the package is its PDE modelling capability, whereby it can link and solve coupled equations from arbitrary fields.

Flexible post-processing and visualisation tools round out the package's extensive capabilities.

The MEMS Module extends these base capabilities by providing application modes optimised for microscale modelling, and separate modes address electrostatics, stresses and strains, piezoelectrics and electrokinetics.

For each application mode users get a customised graphical interface that uncovers the underlying equations so that, without any coding, they can modify the equations or add to them as easily as if working with a pen and paper.

The module also provides predefined physical couplings for several application areas including microsensors, microactuators and microfluidic systems.

Materials modelling, together with the application modes, allows users in research, design, engineering, or education to enjoy a number of significant benefits.

These include the ability to: make quick feasibility studies; optimise a design; experiment with different designs and parameters; and reduce costs by minimising prototyping.

John Dunec of Venture Products is an engineering design consultant who uses Femlab to simulate MEMS devices, and he also teaches courses analysing this technology.

He comments: "MEMS devices are very multiphysics oriented, and only in rare cases is a single physics sufficient for an analysis".

"Femlab is a truly multiphysics code".

"Whichever device I need to simulate, the components are there".

"And when necessary I can easily add any physics required".

"Not many other packages that claim to do multiphysics actually handle the interactional complexities of MEMS".

"They simply don't have the flexibility".

The MEMS Module makes the analysis task straightforward thanks to its convenient application interfaces.

"The MEMS world can present unusual challenges", Dunec elaborates.

"Traditional stress- and strain-analysis tools frequently can't handle some of the more exotic material properties of MEMS devices such as crystalline-optical or piezoelectric materials".

"The MEMS Module offers the flexibility to model these along with moving mesh analyses and more".

"In addition, with new brick and hex meshing we can simulate thin items very efficiently".

Although it's possible to set up a MEMS simulation starting with the basic PDEs or work with the predefined application modes, Comsol further eases the modelling process and allows scientists to more quickly get results thanks to a model library.

It consists of both a separate book and a set of roughly two dozen CD-based model files that users can load directly into Femlab.

To assist in the creation of these models, Comsol enlisted the aid of leading researchers in the field including Dr Carl Meinhart of the University of California at Santa Barbara.

Additional models have also come from members of the fast-growing Femlab users community, such as Isabelle Harouche of the University of Manitoba, Canada, who contributed a simulation of a MEMS comb drive that operates a pair of microtweezers.

These models not only explain the physical phenomena that underlie the operation of MEMS devices, they also illustrate the basic techniques for designing and analysing devices such as sensors, actuators, piezo devices and microfluidic systems.

Towards that goal, these models combine electroelastic, thermoelastic, microfluidic and fluid-structural interactions.

These extensible models thus serve as a convenient starting point for many design tasks.

The book itself contains a section that explains basic MEMS principles, and the documentation for each model elucidates the theory that describes why and how each device or system functions as it does.

Thus, this book serves as a valuable reference work in its own right, just as well suited for the classroom as for the R and D laboratory.

The MEMS Module costs GBP 1995; a single-user perpetual license for Femlab 3.1 is GBP 4995, including support and automatic upgrades for 12 months; special academic pricing is available.

The MEMS Module requires Femlab 3.1, which runs under Windows 98/2000/NT 4.0/XP as well as Linux, Solaris and HP-UX.

64bit support is available under Linux (running on the AMD64 and Itanium processors), and under Unix (for the Solaris and HP-UX operating systems).

The minimum system configuration is a Pentium processor, 256Mbyte of RAM (512Mbyte recommended) and an OpenGL-compatible graphics card.

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