Novel label-free tool for infections diagnosis based on Nano-Electro Optical Tweezers

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I studied theoretically the enhancement of the electromagnetic field of the device using Comsol Multiphysics software in my third year of the project. I have designed and fabricated the size of the nano-aperture comparable to the volume of a single-bacterium so that the microorganism flowing close to the region with a strong field will be trapped, permitting studies at the single-cell level. When the trap was full, there is not energy confined around the trapped bacterium, so preventing, or at least remarkably reducing the probability, that another bacterium will be trapped in the same region. Moreover, by introducing an array of nanohole, many trapping sites have be activated at the same time; hence the proposed approach enabled the simultaneous analysis of several bacteria locally in well-defined positions. By arraying the nanohole, multiple signatures in parallel will be obtained, permitting a measurable signal in case of very weak interaction.I found the theoretical resonance modes of the proposed device. Using antibiotics added to the surrounding medium, I have examined the growth, survival, and reproduction mechanisms of the trapped bacteria using Raman spectroscopy. Unfortunately, the results are not good. As a result, I analyzed the SERS signal during the growth stages of the bacteria. In my study, I found that the intensity of the amide protein characteristics peaks increases during exponential phases and decreases during stationary phases. The results are in agreement with the theoretical explanations.