Biosensor Simulation Using Ansys Lumerical

Hi, I'm Majid Heidari from Ozen Engineering. Today, I'd like to show you how to design a biosensor using Lumerical. We have a Lumerical FDTD and a periodic structure, as shown here. We have epoxy and silicon nitride in this structure, which we want to surround with water or some liquid.

We will simulate the sensitivity on the spectrum. Let's look at the epoxy materials. Epoxy has a refractive index of 1.5, and silicon nitride has a refractive index of 2. 05. You can add any material you wish. Regarding defining materials and structures, I have a complete video on that.

Please look at the AIS part, where I described the fundamentals and basic parameters. The height of silicon nitride is around 120 nanometers, and for epoxy, it's around 200 nanometers. The periodicity of the structure is around 550 nanometers. We have defined the geometry and structure.

Next, we will define a simulation region. The simulation region here is FDTD. We can select add FDTD region. For this reason, you can see the simulation region here. Since this is a periodic structure, just one unit cell is enough. The orange box shows the simulation of one unit cell.

If you right-click on the FDTD and select edit object, you can see that. This simulation is a 2D simulation. Our geometry includes the one unit cell. We use a mesh accuracy of 4. For the boundary condition in the X direction, we have a periodic structure.

For this, we will use a periodic boundary condition for the X and PML for Y. For the advanced operation option, we use the other shutoff means equal to 1e- 9. Next, we define a refined mesh. If I switch to classical mode, you can see that we define a refinement mesh here.

For the geometry, which includes part of the units, we can define a refined mesh in this area. We can define 20 nanometers per 20 nanometers. Next, we will define the source. Our source is injected by a plane wave. The plane wave type here is Broadband periodic because our structure is periodic.

The injection axis is in the Y axis, as you see in the forward direction. The frequency range we are interested in is from 0.75 to 0. 9. We can change this as well. Finally, we have some monitors. We have transmission monitors and reflection monitors.

For the transmission and reflection monitors, you can come to the monitors and select the monitor as you wish. Here, our monitor is a frequency-domain field and power. I will also put some time monitors in different areas, as you see here. Let's run the simulation. Now, we can see the results.

If I come to transmission and select edit object view, transmission, you can see the visualizer part that shows the transmission versus wavelengths. I can change the unit to micrometers.

Here, you can see that we have a dip around 0. 5. You can see that we have a dip around 0. 5. I can do something with the transmission, such as giving it some color. I can zoom in, and you can see that there is some noise.

I just need to change some of the characteristics, especially in the surface area. We can go into that and take a zoom. I can create a sweep like this, but before I create a sweep, I will save time.

If you right-click on a sweep and select edit, you can change the index of FDTD from 1.33 to 1.34 to 1. 35. I'm interested in the result of transmission and reflection monitors. Let's run the sweep and wait for the result. Now the simulation is finished.

If I right-click on the sweep and select visualize and select T, you can see the X axis as lambda and the Y axis as T. Now, if I click on the index and change the value, you can see three different values for the index.

For the 1.35, our central wavelength shifted to 8. 39. We can manage the amount of shifting in the wavelengths by changing the parameters like the periodic structure to have a very efficient biosensor.

If you write "time" and select visualize and select E, you can see how the electric field behaves for different time simulations. We also have a script here. In this script, we just visualize T from the transmission and R from the reflection. And let's run the simulation.

You can see this is the plot we have. We have R as a blue, T as a green, and R plus T as a red. I hope this design shows you the capability of numerical and biosensor design. In biosensor design, we can change the material and study the amount of shifting of wavelengths versus different materials.

Thank you.