Kaivan Karimi – Dir. of Global Strategy, Microcontroller Group, at Freescale

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Kaivan Karimi – Dir. of Global Strategy, Microcontroller Group, at Freescale

Featured Engineer

Interview with Bogdan Firtat

Bogdan Firtat

Bogdan Firtat - Founder of memsOP

How did you get into engineering and when did you start?

While in High School, I was in love with Physics. I studied a lot on many branches of Physics, I ran all the contests available and I was very enthusiastic about a career as a Physicist.

But my career choice took a sudden turn when I actually went for Electrical Engineering, in a technical university. I suppose at that time I felt a bigger attraction for more tangible things, like electronic devices, instead of the more theoretically Physics. And I was right.

During my university studies, I came in contact with Microelecronics and I decided to go for this field as my specialization. I’ve started working in a microelectronics research facility while in my fourth year and I had the chance to discover all the challanges and beauty of this field.

As now I mostly work on sensors and actuators, I think that both my Physics enthusiasm and my Electrical Engineering studies help me better understand the phenomena, structures and devices I deal with.

What about memsOP?

memsOP is a spin-off company, providing services in the field of MEMS and microfluidics design, modelling and optimisation. We managed to put up a team of highly trained scientists, engineers and designers. Our focus is on innovation, quality and user benefits.

What we do is to assist our clients in the process of optimising their devices, trying to minimise their products research costs and time to market. For that, we use dedicated software tools and we perform in-depth modelling and analyses.

But memsOP doesn’t deal only with commercial contracts. We are always happy to perform R&D activities within research projects, which sometimes are more challenging and bring more satisfaction.

What are your favorite software tools that you use?

Since my work focuses on devices design and modelling, FEM and CFD software tools are essential for me. But I don’t think there is one magical software tool, since the MEMS field is very wide and there are many types of devices, phenomena and materials involved. Many of them provide excellent results for some specific situations, while they don’t answer many other questions for other types of devices. In the MEMS field, the software tools that I like best are CoventorWare and COMSOL.

The first one provides an excellent analysis environment for many types of sensors and actuators. It has the great advantage of a design step based on real technological processes, thus being more suitable for users with knowledge in the silicon-processing field. It also features the most important microfluidic issues that can be connected with a MEMS device.

COMSOL, on the other hand, provides a wider area of expertise, not limited to the MEMS field. Within COMSOL, I have more design options, I can use non-standard models and sometimes I can get a more in-depth analysis for my device. But, one of the challenges is that I have to be more aware of the physical (and chemical, sometimes) phenomena that guide the device’s functionality.

The best solution is to combine the powers of the two, depending on the work. This advantage becomes even more important when we’re talking about complex systems that integrate different technologies, such as the lab-on-chip devices, using both sensors (silicon technologies) and microfluidics (polymers or glass).

What are your favorite hardware tools that you use?

My current activities don’t include too many hardware devices (except for the powerful computers that are needed for the modelling). Still, when I entered the MEMS field I learned a lot on the silicon processing technologies and I used a few pieces of equipment in the clean room. That experience is still valuable now, since it provides a better understanding of the devices I’m working on.

What was the biggest challenge that you have to overcome?

A few years ago we decided to enter in the bio-MEMS field, developing different sensors and systems, such as drug delivery systems, medical (even implantable) sensors, lab-on-chip devices. The main issue was to consider the microfluidics elements and phenomena that are usually a main component for such systems.

I had to learn a lot on this new and innovative domain, starting from simple microchannels analysis, to electrokinetic driven fluids, multiple phase flow, fluid-solid interaction issues, porous media and devices that use bubble flow. Each one of these finds its place within modern MEMS systems and I think that an engineer must have the ability to use them.

I eventually managed to broaden my expertise and be active in the technology integration field that opens the door to a multitude of possibilities for an engineer.

What is on your bookshelf?

My technical reading includes mostly articles on MEMS and microfluidics, for the latest findings in the field, or books covering the area such as “Modeling MEMS and NEMS”, by John A. Pelesko and David H. Berstein.

Besides that, I used to be a heavy SF reader as a teenager, where from my passion for technology. But with time I discovered South-American literature and now I really enjoy relaxing with a book of Garcia Marquez or Llosa in my hand.

Do you have any tricks up your sleeve?

I think that two things have great importance when we’re talking about design and FEM modelling. The first one is the meshing step, when you split your model into finite elements. The second one is the ability to incorporate into your model all the elements that might interfere in the analysis results.

Meshing is a tricky action that has to be performed for almost any modelling and simulation job and it is, maybe, the most important process for an FEM/CFD analysis. The finite elements shapes and their numbers affect the simulation results. If they are less than a specific critical mass, the results might not be accurate enough. Also, if their number is higher, the CPU time becomes also higher. And if the system is more complex, this can lead to unacceptable solving times. That’s why, every time, we have to find the best compromise between the finite elements type and number and the computing resources. Or, to perform some tricks, such as increasing the mesh in the most important areas and to decrease it’s density in less sensitive ones.

Regarding the model’s accuracy, one has to make sure that also the design and the physical constraints that are applied to the model perfectly reflects the real world case. If either minor design details (dimensions, shapes, material properties) or the physical and chemical conditions applied to the model differ from the real occurrence, it’s more likely that the results will not be extremely accurate. This is the reason why, when possible, it’s good to compare the results (even partial results) with real life measurements.

What has been your favorite project?

It was a pressure sensor. A simple silicon, piezoresistive, membrane-type pressure sensor. But the client, a domestic appliances company, provided us with a very tight restrictions list, in term of pressure range (that was really low), sensitivity and offset. It was a really challenging job, but we finally managed to have it done, to get a new and competitive product and a satisfied client.

What are you currently working on?

At this point, I’m working on optimising a silicon neural probe. It’s a very challenging device, because it rises both micromechanical and electronics issues.

What direction do you see your business heading in the next few years?

I think biomedical MMS is one of the domains of the future. The microsystems field is in continuous development, and I think that, as people manage to create new techniques and new devices, more and more challenges will have to be overcomed. We’re developing in that area of expertise.

What challenges do you foresee in our industry?

The biggest challenge is our mind. We should never stop asking, questioning and trying. Only by doing that we can evolve and change. At a more specific level, I think new technologies integration is one of the main challenges in the microsystems field. Although important steps have been taken in the last years, we didn’t yet reach a full integration of different technologies, an important step for major breakthroughs in the MEMS field.

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