Modeling and Simulation
One can quickly analyze complex products under development using sophisticated modeling and simulation tools. We know firsthand how critical it is to have a complete understanding of the underlying physics of a product, especially highly complex modern devices that inherently involve lots of coupled physics, also known as multiphysics. Without an in-depth knowledge of the product under development, seemingly small design changes can have drastic consequences in the operation of the product or device.
Emphysys scientists and engineers create realistic models that allow for rapid virtual prototyping of different designs or optimization of an existing design. Our approach eliminates the necessity to fabricate and test lots of different designs in the lab—saving you both time and money further in the development process.
Our state-of-the-art modeling and simulation capabilities in all physics areas are reflected in these projects. Take a look and tell us what you think. We work at the intersection of science and technology to transform your idea into a working technology that we can prove will work and help you get it to market, faster than you thought possible.
Medical Device Modeling
One of the most common challenges in designing medical heating devices is achieving a temperature in the fat region beneath the skin capable of inducing necrosis without damaging surrounding tissue. Using a pulsed power supply and selecting a suitable frequency successfully deals with this challenge. Pictured in the animation below, you can see the temperature and maximum temperature in a cross-section of the human body when using a pulsed RF power supply.
Figure-i: Slice plot of the temperature in a patient’s left abdomen heated via a pulsed power supply.
Figure-ii: Pulsing can improve the depth and uniformity of heating and offer an additional level of control not available with continuous operation power supplies.
RF Heating and Ablation
Figure-iii: Isosurface of the necrotic tissue due to RF heating using an antenna with three independent excitation ports.
One challenge when using high frequency (GHz) electromagnetic radiation to induce thermal ablation in the surrounding tissue is ensuring that necrosis occurs in a uniform area around the antenna. Using simulation, we created an antenna topology to show the formation of the necrosis. This animation shows an isosurface, representing the location of the necrosis front, with a three-port antenna at 1[GHz].
In this example, the shape of the inner and outer antenna loops and the applied current on each loop was optimized to achieve maximum uniformity. Additionally, this greatly reduces the risk of inducing unwanted necrosis in areas surrounding a cancerous region.
Acoustics and Acoustic-Structure Interaction
Figure-iv: Acoustic wave propagation through a human body. Different internal organs are shown in the plot on the right. The acoustic pressure is shown on the left. There is a strong reflection off the spine due to the difference in density and sound speed between bone and the surrounding material.
A common struggle when using acoustic-based imaging and targeting devices on human patients is that constructive interference on the wavefront can lead to regions of very high acoustic intensity, resulting in significant pain for patients. To reduce the acoustic intensity, the wave emitted from the source must create as uniform a field as possible. Typically this requires modeling the pressure waves everywhere and also the shear waves in the plastic applicator that is in contact with the skin. This represents an acoustic-structure interaction problem, requiring a solution that addresses both the acoustics and the solid mechanics. Using modeling and simulation studies, Emphysys designed and optimized the shape of acoustic transducers to ensure field uniformity. The result in medical trials was a reduction in pain and increased target efficiency.
Plasma Modeling
Figure-v: PI Matching Network
Plasma systems represent a tremendous challenge in all aspects of product design. As highly non-linear systems, their characteristics can transform significantly with just a small change in the electrical excitation. Most industrial plasmas operate in the MHz range or higher, requiring a matching network in the power supply. Since the plasma impedance is itself a function of the power supplied, coming up with a stable system is difficult. The impedance is also highly dependent on the gas involved along with the frequency and pressure.
Figure-vi: Plot of the maximum power transfer efficiency and total efficiency vs. frequency for a match with a target operating frequency of 13.56[MHz]. The circuit components are chosen to provide a perfect match at an expected operating condition. Different parameter spaces can then be explored to see if the match will meet the desired specification.
Emphysys has the ability to simulate the coupling between a matching network (such as the PI network shown) and a self-consistent fluid model of the plasma. The match can then be tested for different combinations of gas, pressure and power to ensure that the prototype power supply can meet specification.
Figure-vii: Electron density in an RF excited inductively coupled plasma operating at 13.56[MHz]. The gas is argon and the color represents the electron density (1/m3) which is very high due to the high power (3[kW]) and high pressure (1[torr]).
High pressure and high power discharges also present engineering challenges such as thermally induced mechanical failure. A realistic model of the plasma, produced by Emphysys and shown in figure-vii, provides an accurate indication of where the heat fluxes to the containing walls are at a maximum. The pitch and shape of the coil can be revised to redistribute the heat flux to the surfaces, resulting in lower surface temperatures and less chance of catastrophic failure in the quartz tube.
Figure-viii: Plasma enhanced particle deposition of silicon onto a cylindrical surface. The particles are created via chemical processes in the plasma core, then thermophoresis drives the particles from the hot core of the plasma towards the walls, where they deposit. The black contour lines represent the magnetic field lines, the magenta arrows indicate the magnitude and direction of the thermophoretic force, and the particle color corresponds to the gas temperature (red is hot, blue is cold).
Devices such as the one shown in figure-vii, can be used in a variety of chemical processing applications including deposition. Modeling the creation and agglomeration of particles in a plasma is quite challenging since many competing forces need to be considered; such as the drag force, particle charging, thermophoresis, gravity and lift.
App Development
Figure-ix: Custom application to help better understand an electromagnetic heating device. The underlying model is rather complex. It uses complicated electrical excitation, periodic boundary conditions and a full solution of Maxwell’s equations. In the application, the user can make changes to the geometry, materials and electrical parameters without having to understand the physics, mesh and solver settings. Results are presented in the form of lumped parameters and plots. A comprehensive report can be generated for a given set of input parameters.
Custom applications are highly useful in better understanding your products. Setting up a full multiphysics model of a complex system is a significant challenge; one requiring expertise in not only the physics, but also operation of the software. By placing a simple user interface on top of the model with a limited set of inputs, Emphysys engineers explore different parametric spaces of a given design without worrying about the underlying physics settings, mesh generation and solver settings. The resulting application can be an executable file that can be run on any computer without any license requirements.
Our services are honed from years of challenging ourselves and you, our clients, to think bigger. We look to build and sustain long-term partnerships and trusted relationships with our clients while pushing you to drive your concepts further than you thought possible. Together, let’s push the boundaries of technology and innovation to create something truly revolutionary.
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