Today marks the conclusion of my internship at @tuberlin 🎓 I had an incredible research experience, thanks to my supervisor, Professor Mario Birkholz (see picture), and my advisors, Professor Anders Henriksson and Phillip Schrenk.

During this time, I learned about the innovative technology of silicon optical sensors 🔬💡 and developed as a researcher by enhancing my data collection methods 📊 and improving the experimental setup. ⚙️ I also honed my skills in interpreting numerical data 📈 and testing hypotheses.

@JLBe
#bioelectronic #microelectronic #biosensor

I am pleased to share that I successfully coupled the laser radiation into the chip.

After two weeks of learning about the concepts of the micro-ring resonators (#MRR) and attempting to capture the resonances, I finally achieved my goal.

The main challenge I faced was accurately cutting the optical fiber and determining the optimal distance and angle between the fiber and the #waveguide for effective coupling. This process required a significant amount of trial and error. Additionally, for an entire week, I unknowingly worked with a chip that had broken couplers. When I adjusted the z-axis, I accidentally damaged the couplers with the fiber. Fortunately, I have a sufficient number of chips available for multiple trials.

#biosensor #bioelectronic #microelectronic @JLBe @tuberlin

How are the #microelectronic #bioelectronic chips produced?🤔

The production starts from the blank silicon wafers. Layering follows, where insulating and conductive materials are deposited onto the wafer. The #wafer is then covered with photoresist, and UV light is shone through a photomask to pattern the circuit of the sensor. Next comes the etching process, using chemicals or plasma to remove areas without photoresist. Doping is applied afterwards to alter the electrical properties of the silicon.
These steps are repeated in cycles to build the complex interconnected structure of the chip. Subsequently, layers of metal are deposited to establish connections between the circuit elements. Once completed, the wafers are tested for defects and then packaged 🤯 .

For a demonstration of this process, check out the video from #ihpmicroelectronics (https://www.ihp-microelectronics.com/news-2/mediathek/videos). In the previous post, we showed how the #silicon chip originated from this wafer.

The picture shows a full wafer glued to blue tape for chip separation by sawing, from which some #biosensor chips have already been taken.

#biosensor @tuberlin

The microring resonator (#MRR) operates by the principle of evanescent field.

By what? 🤔

Sensors that operate by the principle of an #evanescent field utilizes the extension of the field inside the MRR into the surrounding. The range of this extension is in the order of the wavelengths of the radiation, ie in our case 1.5 micrometers. For #biodetection applications, target #biomolecules caused a variation of the refractive index in the surrounding and a shift in the resonance peak.

See the figure below from E. Luan et al (2018) https://doi.org/10.3390/s18103519

#bioelectronic #microelectronic #biosensor @JLBe @tuberlin