Welcome to the Webinar

Hello everyone and welcome to this webinar. My name is Adel Benleulmi. I am a high frequency application engineer with OSA Engineering. In this presentation, I will talk about substrate integrated waveguide techniques for biosensor devices and how we can optimize them using ANSYS HFSS.

We are OSA Engineering, an elite channel partner of ANSYS. We have been named ANSYS channel partner of the year in 2015, 2018, and 2021. Our company specializes in ANSYS software tools and provides best-in-class services for training, mentoring, consulting, and technical support.

We will start this presentation with a brief overview of the biosensing market and technologies, including what biosensing is, its applications, and the available types of biosensors.

We will then explore the SIW technology and talk about ANSYS HFSS, a powerful simulation tool used for designing and optimizing SIW biosensors.

Following this, we will review some of the SIW techniques used for biosensing applications and demonstrate some of the useful features for designing and optimizing a biosensor in the field of biosensing.

We will also talk about the various technologies used for designing and optimizing SIW biosensors. The biosensing market is rapidly growing and involves detecting and analyzing biological components and processes.

Biosensors are devices that detect one or more biological components and can be used in medical diagnostics, environmental monitoring, and food safety. They provide a simple, fast, and sensitive means of detecting biological molecules and processes.

Key technologies in the biosensing market include electrochemical sensors, optical sensors, and microelectromechanical systems. The biosensing market has applications in healthcare, environmental monitoring, food safety, and other areas.

For instance, biosensors can be used to detect pathogens in food, monitor environmental pollutants, or diagnose diseases by detecting specific biomarkers.

The biosensing market is driven by increasing demand for faster and more accurate diagnostic tools as well as the development of new biosensing technologies.

Researchers are constantly innovating and developing new biosensing techniques based on emerging technologies, which will continue to drive growth in the market.

Today, we are going to discuss one of these technologies that is relatively new and has shown great potential for biosensing applications and cost-effectiveness.

The substrate integrated waveguide technology was first introduced in the early 2000s by Professor Kewu, a professor at the École Polytechnique de Montréal and his team, in response to the growing demand for high-performance and compact microwave and microelectromagnetic systems.

The technology was developed as a solution to the limitations of traditional waveguide technology and has since found numerous applications in wireless communication systems, microwave sensors, and biosensors.

The invention of the SIW technology has led to significant advancements in the field of microwave and millimeter wave electronics, enabling the development of new biosensing technologies.

Its high-performance properties make it well suited for use in biosensors, where accuracy and sensitivity are critical. Before we jump in and talk about substrate integrated waveguides, we need to first understand what a waveguide is, and more specifically, what a rectangular waveguide is.

A rectangular waveguide is a hollow metal tube designed to guide and confine electromagnetic waves at microwave frequencies. It has a rectangular cross-section, with one side being longer than the other, and the frequency range of operation depends on these dimensions.

The waveguide is typically made of metal, such as copper or aluminum, and it is used to transmit microwave energy from one point to another.

The advantage of rectangular waveguides is that they can handle high power levels, they have low loss, and they provide good shielding against electromagnetic interference.

However, they are larger and heavier than other types of transmission lines and can be more difficult to manufacture and assemble. Substrate integrated waveguides are basically the planar form of rectangular waveguides. They are constructed using printed circuit board technology.

SIWs are typically used to transmit electromagnetic waves at microwave and millimeter wave frequencies and offer advantages over other types of waveguides, such as smaller size, ease of integration with other components, and lower loss at high frequencies.

Because of their planar structure, SIWs are easier to manufacture and can be integrated with other planar circuits on a PCB, making them a popular choice for many applications in microwave and millimeter wave engineering. Here you can see the E-field simulated using ANSYS HFSS for both structures.

This is for the fundamental mode, the TE 10. Substrate integrated waveguides have lower cost and weight compared to rectangular waveguides and can be integrated with various passive and active components. They are also self-shielded, making them less susceptible to external interference.

However, the insertion loss, quality factor, and power handling of substrate integrated waveguides are not as high as that of classic rectangular waveguides. An SIW structure is composed of two metallic layers, typically made of copper, with a dielectric substrate material between them.

The top and bottom layers are connected together using vias, which provide electrical continuity between the layers and allow the waveguide structure to be formed within the substrate material. The theory behind SIW structures is similar to that of rectangular waveguides.

They have a cutoff frequency, which is the lowest frequency at which a particular mode can propagate through the waveguide. This cutoff frequency depends on the dimensions of the waveguide, the mode number, and the dielectric constant of the substrate.

For the fundamental mode, TE10, the cutoff frequency can be calculated using this formula. But note that in SIWs, only TE modes can propagate because of the gaps between the vias, which serve as the sidewalls of the waveguide.

The gaps would not allow for longitudinally oriented E-fields, and therefore TM modes do not exist. The design equations shown here are used to determine the equivalent width and length of an SIW.

Although there are many articles on designing SIWs, simulations are extremely important to validate theory and optimize circuits before moving on to manufacturing. Some other types of substrate integrated waveguides are shown here.

The first one is the half-mode SIW, which is a standard SIW cut-in-half to reduce the size. We will now use ANSYS HFSS to demonstrate some of the useful features when designing and optimizing a biosensor. HFSS stands for high-frequency structure simulator.

It is a 3D electromagnetic simulation software that is widely used for simulating high-frequency electromagnetic fields in a variety of applications, including antennas, microwave components, and radio frequency circuits.

HFSS uses the finite element method to solve Maxwell's equations in the time domain or frequency domain. It can simulate the behavior of electromagnetic fields in complex geometries, including materials with varying properties, and it can also take into account the effects of losses and dispersion.

HFSS is a powerful tool for designing and optimizing electromagnetic devices and systems. It provides a comprehensive set of simulation capabilities, including parametric analysis, optimization, and electromagnetic field visualization.

Its accuracy due to the automatic adaptive meshing and flexibility make it a popular choice for researchers and engineers in the fields of electromagnetic and radio frequency engineering.

With HFSS, we can accurately model substrate integrated waveguide biosensors with complex geometries and materials. HFSS has optimization tools to improve biosensor performance and reduce size and cost.

Advanced algorithms and parallel computing speed up simulations, allowing for quick evaluation of designs. We can integrate HFSS with other ANSYS tools and enable multi-physics simulations and comprehensive analysis. And we have post-processing tools for the simulation of the model.

With all the benefits of using SIW technology, many microwave and millimeter wave components have been developed, published, and even patented.

The number of scientific publications in which researchers develop SIW filters, antennas, amplifiers, and many other components using ANSYS HFSS has been impressively increasing over the years.

Here, we can see some of the most recent HFSS applications, including published SIW biosensors developed with HFSS. SLW biosensors are capable of detecting the presence and measuring the concentration of biomolecules in low concentrations.

They can measure the concentration of certain liquids using microbiology, such as glycerol, ethanol, and methanol. SIW biosensors have shown a good potential for early cancer detection and are currently being researched and developed for this application.

Now that we have discussed substrate integrated waveguides and their different types, let's explore some techniques used in the development of SIW biosensors with the help of ANSYS HFSS.

The majority of SIW biosensors use the resonance technique due to the benefits it offers, such as high sensitivity and selectivity. Another technique used in the development of SIW biosensors is the use of transmission lines.

By introducing phase shifts in the signal transmitted through the SIW, it is possible to detect changes in the dielectric constant of the material placed in the sensing region of the waveguide.

This technique has the advantage of being relatively simple to implement and does not require any resonant structures, which can be beneficial in some applications. Here, we have an example of a substrate integrated cavity resonator.

By injecting the material under test in the structure, we change the effective dielectric constant and, therefore, the resonant frequency. For different materials, we have a different frequency.

The advantage of this structure compared to the resonator is that the structure is broadband and also if we use lossy materials, we'll still be able to see the phase shift. We can estimate the effective permittivity by the Maxwell-Garnett mixing rule given here.

In summary, by using ANSYS HFSS to design and optimize SIW biosensors, designers can improve the sensitivity, selectivity, and performance of their biosensors without the need for physical prototyping and testing of SIW sensors.

At OSA Engineering, we provide technical support for a wide range of ANSYS software tools that cover not only electronics but also various other fields of physics. We have multiple offices located on both West and East Coast, as well as in Canada.

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