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Reversible and tunable photochemical switch based on plasmonic structure

H. Mbarak1, R. Taheri Ghahrizjani, S. M. Hamidi1, E. Mohajerani1, Y. Zaatar

For the first time, pyranine (8-hydroxypyrene-1,3,6-trisulfonate, HPTS) is studied for realizing active plasmonic control, which is attracted considerable attention owing to its unique photophysical and photochemical properties. We have used this photoacid (HPTS) as an active surrounding medium that can be optically controlled and used for modulating plasmon resonances. In this paper, the fabrication of 2D-plasmonic grating coated by thin film of HPTS exposed to UV irradiation is reported. By switching the UV light on and off, the HPTS thin film maintains an excited-state proton transfer (ESPT) process followed by green fluorescence resulting in a plasmonic redshift caused by the variation of the refractive index. Furthermore, this photochemical active medium has also played another important role in plasmonic sensing, in which the emission-based response of HPTS thin film in 2D-plasmonic grating to water vapor upon photoexcitation is demonstrated, for both s and p polarizations. This tunable, flexible and reversible light-driven system will enhance the development of active plasmonic structures and will have a great influence on many fields such as, biochemical optical sensors and all-optical plasmonic circuits.

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Biosensing applications of all-dielectric SiO2-PDMS meta-stadium grating nanocombs

M. GHASEMI, N. ROOSTAEI, F. SOHRABI, S. M. HAMIDI, AND P. K. CHOUDHURY

Laser and Plasma Research Institute, Shahid Beheshti University, Daneshju Blvd., Tehran 19839 69411, Iran

Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, UKM Bangi, 43600 Selangor, Malaysia

Thin film grating meta-stadium nanocombs were fabricated and experimentally investigated for the purpose of glucose monitoring. The method of ellipsometry was used to study the sensitivity of the structure to the alterations in glucose concentration in aqueous solution. The existence of Tamm surface waves was demonstrated at the interface of two dielectric mediums (PDMS and SiO2) with acceptable resolution. The results revealed the best sensitivity achieved at a 48° angle of incidence over 350 − 450 nm visible wavelength span when the glucose concentration was varied in the range of 50 mg/l to 100 mg/l. Though the present work emphasizes on the monitoring of glucose, the structure can be used for sensing applications of other biological fluids as well.

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Our new paper is accepted in the Journal of Applied Physics. This manuscript has been performed collaboratively by the authors of our group and Ecole Polytechnique Federale de Lausanne (EPFL).
Congratulations to all the authors!

Phase-Sensitive Optical Neural Recording of Cerebellum Tissue on a Flexible Interface

Foozieh Sohrabi,1,2 Dordaneh Etezadi,2 Rodrigo De Campos Perin,3 Yasaman Jahani,2 Ershad Mohammadi,2,4 and Seyedeh Mehri Hamidi*,1

1Magneto-Plasmonic Lab, Laser and Plasma Research Institute, Shahid Beheshti University, Daneshju Boulevard, Tehran 1983969411, Iran

2Institute of Bioengineering, École Polytechnique Fédérale De Lausanne, Ch-1015 Lausanne, Switzerland

3School of Life Sciences, École Polytechnique Fédérale De Lausanne, Ch-1015 Lausanne, Switzerland

4Department of Electrical Engineering, Amirkabir University of Technology, Tehran, Iran

ABSTRACT: Knowing an increased number of the patients suffering from mental disorders, neural signal recording and imaging have become highly prerequisite challenges for providing healing procedures. Despite the fact that novel optical techniques provide highly-resolved imaging/recording of large neuron population, most of them are suffering from insertion damage, tethering connection, labeling and photobleaching deficiencies, among which plasmonic Ellipsometry is a highly sensitive and label-free platform for detecting neural activity both quantitatively and qualitatively. In this paper, a flexible patterned plasmonic substrate is used as a sensing surface for phase-sensitive neural recording of cerebellum tissue slice under electrical and chemical stimulations. Although the traditional reflection spectrum cannot represent the changes in neural activity with high-precision, phase-sensitive neuroplasmonics not only can reveal the neural activity level but also distinguish different electrical and chemical stimulation types with considerable phase splitting factor. This study can open up a new insight toward label-free and flexible biological sensors with neuroscience applications.

KEYWORDS: Plasmonic, Ellipsometry, Phase-sensitive, Neural signal, Brain tissue, Flexible interface.

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Tunable Low Power Piezo-Plasmonic Random Laser under External Voltage

S. F. Haddawi, Hammad. R. Humud, S. M. Hamidi *

This study was aimed to introduce a new kind of low power and tunable random lasers based on piezo-plasmonic core/shell nanoparticles (NPs) consisting of lead zirconate titanate and gold, mixed by different concentrations of Rhodamine B (RhB) dye. To get the random lasing, the sample was exposed to pulsed laser at the presence and in the absence of an external voltage. We got a gradual increase in the thermo-plasmonic properties by increasing the applied voltage on core/shell NPs, which depended on the boundary conditions between the shell and the core samples. By external voltage, the emission intensity was enhanced by decreasing the threshold lasing due to an increase in scattering, which more easily made a close loop path in the gain medium. Our results showed some spikes with the same pump energy in emission spectrum which confirmed the coherence random lasing.

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in these days, Nature journal publishes a paper entitled as ” Vacuum Rabi splitting of a dark plasmonic cavity mode revealed by fast electrons”

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Utilizing ZnO Nanorods for CO gas detection by SPR techniques

H. fallah, T. Asadishad, M. Shafiei, B. Shokri, S. Javadianaghezi, W. S. Mohammed, S. M. Hamidi*

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Tunable thermo-piezo-plasmonic effect on core shell nanoparticles under laser irradiation and external electric field

by A. K. Kodeary, M. Abdulfadhil Gatea, S.F. Haddawi,S. M. Hamidi

This work is focused on the characterization of the opto-heating generation in thermo-piezo-plasmonic solutions of Gold-PbZrTiO3 (PZT) core/shell nanoparticles. Core/shell nanoparticles have been prepared by the laser ablation in liquid method (LAL). Linear and nonlinear optical properties of proposed nanoparticles were studied by optical spectroscopy and the Z-scan technique under external voltage to investigate the piezo-photonic effect. Furthermore, the linear optical properties of these nanostructures were calculated vie dipole approximation method with different core size and different shell thickness of samples immersed in water and Poly-vinyl-pyrrolidone (PVP). In addition, thermo-plasmonic effects of samples are investigated theoretically and experimentally by the finite element method of COMSOL multiphysics V5.4 and infrared camera under laser irradiation and external electric field. The results revealed a clear tunable and adjustable linear and nonlinear behavior and thermo-piezo-plasmonic properties under external effects. The temperature elevation is ranging of ∆T = 3.7–14.1°C under different external effects. Accordingly, these results encourage to uses proposed samples for the cancer treatment and the different biomedical applications.

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Chapter 1. Thermodynamic of Gold Nanoparticles


M. Abdulfadhil Gatea, A. K. Kodeary, S. F. Haddawi and S. M. Hamidi, Computer Technical Engineering Department, Colleague of Technical Engineering, The Islamic University, Najaf, Iraq, and others

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Congratulations for acceptance of two chapter books of our team:

Chapter 4. Polydimethylsiloxane (PDMS): A Promising Material for Biological Applications
(Sajede Saeidifard, Foozieh Sohrabi and Seyedeh Mehri Hamidi)

Chapter 6. Polydimethylsiloxane (PDMS): A Favorable Material for Active Plasmonic Applications
(Houssein Mbarak, Seyedeh Mehri Hamidi and E. Mohajerani)

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Voltage Controlled Properties of Piezo-Magneto-Plasmonic Core/shell Nanoparticles

A. K. Kodeary, S. M. Hamidi, R. Moradlou

The present experimental study aimed to synthesize and evaluate the magneto-plasmonic and piezophotonic properties of Cobalt-based nanoparticles to introduce a new type of core/shell nanoparticles usable in biomedicine and optical applications. For these core/shell nanoparticles, Lead Zirconate Titanate (PbZrTiO3) and Gold as a partner of Cobalt were used in piezophotonic and magneto-plasmonic parts, respectively. Then, their bare nanoparticles and core/shell were prepared by laser ablation in liquid method by using Nd: YAG laser pulse irradiation in Poly vinyl pyrolidone (PVP), as well as water solution. In the next step, the linear optical properties of these nanostructures were measured by spectrometry and calculated by dipole approximation method. Based on the results, super paramagnetic or ferromagnetic properties in the core/shell nanoparticles were achieved by changing in the surrounding medium. In addition, very nice tunable and adjustable piezo magnetism was obtained by tracing nonlinear refractive index under external voltage and host mediums. The results can open new insight in piezo-magneto-plasmonic area for useful biomedical applications.


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