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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - PLASMECS (NanoPlasmoMechanical Systems)

Teaser

Summary

\"With their unparalleled mass, force, and temperature sensitivities, nanomechanical resonators have the potential to considerably improve existing sensor technology in various fields such as life sciences or telecommunications. However, one major obstacle still stands in the way of their practical use: The efficient transduction (actuation & detection) of the vibrational motion of such tiny structures. Localized plasmon resonances \"\"focus\"\" optical fields below the diffraction limit of light and present a powerful new method to optically transduce the vibrational motion of nanomechanical structures. The objective of this project is to study fundamental effects of plasmomechanical systems and establish for the first time a complete plasmonic transduction in novel NanoPlasmoMechanical Systems (NaPlaMS).

In this project we explore the ground-breaking new properties of NaPlaMS pillar arrays in three mutually supporting subprojects (SP):

In SP1 we study fundamental aspects of plasmomechanics. These devices allow the unique optical and mechanical study of i) plasmonic quantum tunneling, ii) optical forces between plasmonic nanostructures of various shapes and materials, and iii) the photothermal heating of individual nanostructures and molecules. Our technology not only allows for the analysis and identification of individual plasmonic nanoparticles, but also for samples such as individual bacteria, viruses, proteins, or small molecules. This sensor technology can significantly improve and speed up the identification of pathogens (bacteria or viruses) in order to administer the most effective medication. The identification of individual nanoparticles and bacteria is also of high importance in the field of environmental monitoring and in occupational health, keeping our environment and work place save. The analysis of individual proteins and ultralow protein concentrations will speed up the development of new drugs.

In SP2 we make use of the strong plasmomechanical light-interaction of the high frequency NaPlaMS pillars for the development of next generation reconfigurable metamaterial for optic modulation. Compared to state-of-the-art bulky and power- hungry modulators, NaPlaMS modulators will be low-power and sub-wavelength-size as required for future optic telecommunication and consumer products.

In SP3 we utilize the exceptional mass sensitivity of NaPlaMS pillar arrays to create unique mass sensors. The goal is to create a sensor for native & neutral protein mass spectrometry to provide a revolutionary small and cheap tool for proteomics, which will accelerate the development of protein drugs.\"

Work performed

\"- We have developed a novel nanoplasmomechanical system that allows the study of plasmomechanical interactions such as the optical near-field forces existing between small plasmonic nanoparticles.

- We have studied the photothermal coupling of individual plasmonic nanoparticles with a nanomechanical drum resonator. We have developed a novel method for enhancing the photothermal response of our nanomechanical sensors [1]. We could enhance the response of our resonator not only to be able to analyse and image individual plasmonic nanoparticles but even single molecules with a record high signal-to-noise-ratio [2].

- We have developed a fabrication method allowing for the creation of plamomechanical metamaterials. This reconfigurable metamaterial will be used to develop an ultracompact electro-optic modulator [3].

- We have developed a new transduction technique, by coupling of surface acoustic waves to nanomechanical pillars. This technique allows the efficient actuation and readout of nanopillar resonators for the use as ultasensitive gravimetric mass sensors that can be used for protein mass spectrometry.

- We have developed a new method to purify Au nanostructures that have been created by focused electron beam induced deposition (FEBID). We reach purities that are high enough such that these FEBID Au nanostructures showed strong plasmonic responses.

- We have developed a new method allowing for the optical measurement of the conductivity of single plasmonic metal nanoparticles. This method is based on the optical absorption measurement by nanomechanical photothermal sensing.

[1] N. Luhmann, A. Jachimowicz, J. Schalko, P. Sadeghi, M. Sauer, A. Foelske-Schmitz, S. Schmid: \"\"Effect of oxygen plasma on nanomechanical silicon nitride resonators\"\", Applied Physics Letters, 111 (2017), 063103.
[2] M.-H. Chien, M. Brameshuber, B. Rossboth, G. SchÃ¼tz, S. Schmid: \"\"Single-molecule optical absorption imaging by nanomechanical photothermal sensing\"\", PNAS - Proceedings of the National Academy of Sciences of the United States of America, 115 (2018), 44; 11150 - 11155.
[3] P. Sadeghi, W. Kaiyu, A. Boisen, S. Schmid:\"\"Fabrication and characterization of Au dimer antennas on glass pillars with enhanced plasmonic response\"\", Nanophotonics, 30-6-2017 (2017).\"

Final results

- Absorption microscopy with single-molecule sensitivity.
- Identification (fingerprinting) of individual samples such as bacterias, virus, nanoparticle, and molecules with nanomechanical absorption spectroscopy.
- Optical conductivity measurement of plasmonic metal nanoparticles.
- Controlled measurement of near-field force between plasmonic dimer antennas.
- Full optical transduction of nanoplamomechachanical pillar arrays.
- Transduction of nanomechanical pillars with surface acoustic waves.
- Gravimetric protein mass spectrometry with 1kDa sensitivity.
- Deposition of pure plasmonic Au nanostructures with FEBID.
- Electro-optic modulation with reconfigurable plasmonic metamaterial.