Query: Properties of split ring resonators metamaterials terahertz sensor on flexible substrates

Candidate papers:

abstract: Enhance sensitivity of the terahertz (THz) wave sensor by the THz wave control characteristic based on artificial electromagnetic meta materials, is a hot spot in current research. The performance of split ring resonators (SRRs) THz sensor on Mylar substrate is numerical simulated with COMSOL Multiphysics software in this paper. The two key characteristic parameters of the THz sensor are analyzed with COMSOL Multiphysics software, which are the thickness of the Mylar substrate and the gap width of the gold SRRs. By comparing the relationship between different parameters and the corresponding resonance frequency curve, the optimal parameters of the THz sensor are obtained which are 10 microns for the Mylar substrate thickness, 2 microns for the gap width of gold SRRs. Then the optimized THz sensor model is used to test the different thickness and relative dielectric constant material with the COMSOL Multiphysics software. The results show that the resonant frequency (f0) move to lower frequency with the increase of the relative dielectric constant of tested materials, and has a good linear relationship between the f0 and the relative dielectric constant of tested materials. While the f0 also move to lower frequency as the thickness of tested materials are increase, but when the thickness are more than 5 microns, the resonance peak stay at near 1.997 THz. They are show that the SRRs THz sensor on flexible substrate has high measurement precision, sensitivity, and reliability when the tested materials are common metal, semiconductor and medium layer which layer thickness is less than 5 microns, and the relative dielectric constant for the range of 1 4 by the linear relationship between the resonance frequency and the different parameters of tested materials, as well as it can provide theory references for actual testing of such terahertz sensors.
author_names: Tianhua Meng

Guozhong Zhao

Wenyu Li

Ran Sun

Yu-He Lu

Ru Huang
title: Properties of split ring resonators metamaterials terahertz sensor on flexible substrates
venue: SPIE/COS Photonics Asia
year: 2020

abstract: We demonstrate a significant enhancement in the sensitivity of split ring resonator terahertz metamaterial dielectric sensors by the introduction of etched trenches into their inductive capacitive gap area, both through finite element simulations and in experiments performed using terahertz time domain spectroscopy. The enhanced sensitivity is demonstrated by observation of an increased frequency shift in response to overlaid dielectric material of thicknesses up to 18 um deposited on to the sensor surface. We show that sensitivity to the dielectric is enhanced by a factor of up to ~2.7 times by the incorporation of locally etched trenches with a depth of ~3.4 um, for example, and discuss the effect of the etching on the electrical properties of the sensors. Our experimental findings are in good agreement with simulations of the sensors obtained using finite element methods.
author_names: Kun Meng

S J Park

Andrew D Burnett

T B Gill

Christopher David Wood

Mark C Rosamond

L Li

Li-ping Chen

David R Bacon

J R Freeman

Paul Dean

Yeong Hwan Ahn

Edmund H Linfield

A G Davies

John E Cunningham
title: Increasing the sensitivity of terahertz split ring resonator metamaterials for dielectric sensing by localized substrate etching.
venue: Optics express
year: 2019

abstract: Volatile sensing in the terahertz (THz) spectrum is attractive since many volatile molecules exhibit unique spectral signatures with higher absorption strength. In this paper, a practical approach for volatile molecular sensing at atmospheric pressure and room temperature in the THz spectrum is investigated. A metamaterial based periodic split ring resonator is designed on a porous flexible substrate and is placed in the optical beam path of a THz signal enclosed inside a sealed chamber. Different volumes of volatiles are introduced into the chamber and the resonance frequency is monitored over time. The substrate porosity naturally allows condensing of volatile molecules into the pores through capillary condensation and surface adsorption. This changes the effective substrate dielectric constant leading to a shift in resonance frequency. The frequency shift dynamics can be monitored for identifying different volatiles and enables profiling. The proposed sensing technique is non destructive in nature and can be easily adapted for monitoring volatiles emitted inside packaged food along a supply chain. The developed sensor tag is flexible and can be easily integrated with existing microsystems packaging technology.
author_names: Saranraj Karuppuswami

Jennifer A Byford

Premjeet Chahal
title: A Volatile Molecular Sensor Using Terahertz Resonators on Porous Substrates
venue: 2018 IEEE 68th Electronic Components and Technology Conference (ECTC)
year: 2018

abstract: Microscopic split ring resonator (SRR) arrays are fabricated on 100 mm thick polyethylene naphthalate (PEN) films by femtosecond laser micro lens array (MLA) lithography. The transmission properties of these metamaterials are characterized by THz Time Domain Spectroscopy (THz TDS) Tunable resonance responses can be achieved by changing SRR structural design parameters. By stacking 2D PEN metamaterial films with different frequency responses together, a broadband THz filter with full width at half maximum (FWHM) of 0.38 THz is constructed. The bandwidth of the resonance response increases up to 4.2 times as compared to the bandwidths of single layer metamaterials. Numerical simulation reveals that SRR layers inside the multi layer metamaterials are selectively excited towards specific frequencies within the broadband response. Meanwhile, more than one SRR layers respond to the chosen frequencies, resulting in the enhancement of the resonance properties. The multi layer metamaterials provide a promising way to extend SRR based metamaterial operating region from narrowband to broadband with a tunable feature.
author_names: Ningren Han

Z C Chen

Chu Sing Lim

Binghao Ng

M H Hong
title: Broadband multi layer terahertz metamaterials fabrication and characterization on flexible substrates.
venue: Optics express
year: 2011

abstract: We demonstrate micromachined reconfigurable metamaterials working at multiple frequencies simultaneously in the terahertz range. The proposed metamaterial structures can be structurally reconfigured by employing flexible microelectromechanical system based cantilevers in the resonators, which are designed to deform out of plane under an external stimulus. The proposed metamaterial structures provide not only multiband resonance frequency operation but also polarization dependent tunability. Three kinds of metamaterials are investigated as electric split ring resonator (eSRR) arrays with different positions of the split. By moving the position of the split away from the resonator's center, the eSRR exhibits anisotropy, with the dipole resonance splitting into two resonances. The dipole dipole coupling strength can be continuously adjusted, which enables the electromagnetic response to be tailored by adjusting the direct current (DC) voltage between the released cantilevers and the silicon substrate. The observed tunability of the eSRRs is found to be dependent on the polarization of the incident terahertz wave. This polarization dependent tunability is demonstrated by both experimental measurements and electromagnetic simulations. Researchers in Singapore have developed metamaterials whose shape and optical properties can be easily reconfigured. Metamaterials are artificial structures much smaller than the wavelength of light that can achieve functionalities not possible with conventional optics. Chengkuo Lee and colleagues at the National University of Singapore achieved reconfigurable control by fabricating metamaterials on micrometer scale cantilevers. Applying an electrical voltage bends the cantilevers vertically and thus changes the shape of each component in the metamaterial. As the active elements of the device move away from each other with increasing cantilever height, the optical resonance of the device shifts. The researchers performed their investigation in the terahertz regime, although in principle the concept can be applied to the entire electromagnetic spectrum. This approach could lead to novel applications in which optical functionalities can be freely tuned by an electrical voltage.
author_names: Fusheng Ma

Yu-Sheng Lin

Xinhai Zhang

Chengkuo Lee
title: Tunable multiband terahertz metamaterials using a reconfigurable electric split ring resonator array
year: 2014

abstract: Sub wavelength metamaterial structures are of great fundamental and practical interest because of their ability to manipulate the propagation of electromagnetic waves. We review here our recent work on the design, simulation, implementation and equivalent circuit modeling of metamaterial devices operating at Terahertz frequencies. THz metamaterials exhibiting plasmon induced transparency are realized through the hybridization of double split ring resonators on either silicon or flexible polymer substrates and exhibiting slow light properties. THz metamaterials perfect absorbers and stereometamaterials are realized with multifunctional specifications such as broadband absorbing, switching, and incident light polarization selectivity.
author_names: Mohammad P Hokmabadi

Soner Balci

Ju-Hyung Kim

Elizabath Philip

Elmer Rivera

Muliang Zhu

Patrick Kung

Seongsin Margaret Kim
title: Terahertz metamaterials: design, implementation, modeling and applications
venue: SPIE Commercial Scientific Sensing and Imaging
year: 2016

abstract: Metamaterials are artificial composites that acquire their electromagnetic properties from embeded subwavelength metalic structure. With proper design of metamaterials, numerrous intriguing phenomena that not exhibited naturally can be realized, such as invisible cloaking, perfect absorption, negative refractive index and so on. In recent years, With the development of THz technology, the extensive research onTHz metamaterials devices areattracting more and more attentions. Since silicon (Si) has a higher transmittance for THz wave, it is usually selected as substrate in metamaterials structure. However, Si has the shortcomings of hardness, not easy to bend, and fragile, which limit the application of THz metamaterials. In this work, we use polyimide as the substrate to overcome the shortcomings of the Si substrate. Polyimide is flexible, smooth, suitable for conventional lithography process and the THz transmittance can compete with that of the Si. Frist, we test the THz optical properties of polymide, and get the refractive index of 1.9, and the transmittance of 80% Second, we design a double splits ring resonators (DSRRs) and study the properties of transmission by changing the THz incidence angle and curvature of the sample. We find the resonant amplitude and resonant frequencies are unchanged. Fabricating metamaterials structures on a thin plastic substrate is a possible way to extend plane surface filtering to curved surface filtering. Third, we try to make a broadband filter by stacking two samples, and the 181GHz bandwidth at 50% has been achieved. By stacking several plane plastic metamaterial layers with different resonance responses into a multi layer structure, a broadband THz filter can be built. The broadband filter has the advantages of simple manufacture, obvious filtering effect, which provides a new idea for the production of terahertz band filter.
author_names: Jun He

Tiejun Zhang

Wei Xiong

Bo Zhang

Ting He

Jing-ling Shen
title: [A Double Split Ring Terahertz Filter on Ploymide Substrate]
venue: Guang pu xue yu guang pu fen xi Guang pu
year: 2015

abstract: We demonstrated the fabrication of terahertz metamaterial sensor for the accurate and on site detection of yeast using electrohydrodynamic jet printing, which is inexpensive, simple, and environmentally friendly. The very small sized pattern up to 5 ?m width of electrical split ring resonator unit structures could be printed on a large area on both a rigid substrate and flexible substrate, i.e. silicon wafer and polyimide film using the drop on demand technique to eject liquid ink containing silver nanoparticles. Experimental characterization and simulation were performed to study their performances in detecting yeast of different weights. It was shown that the metamaterial sensor fabricated on a flexible polyimide film had higher sensitivity by more than six times than the metamaterial sensor fabricated on a silicon wafer, due to the low refractive index of the PI substrate and due to the extremely thin substrate thickness which lowers the effective index further. The resonance frequency shift saturated when the yeast weights were 145 ?g and 215 ?g for metamaterial structures with gap size 6.5 ?m fabricated on the silicon substrate and on the polyimide substrate, respectively.
author_names: Ayodya Pradhipta Tenggara

S J Park

Hadi Teguh Yudistira

Yeong Hwan Ahn

Doyoung Byun
title: Fabrication of terahertz metamaterials using electrohydrodynamic jet printing for sensitive detection of yeast
year: 2017

abstract: Given the ability to bend, stretch and roll like stretchable electronics, the newly developed metamaterial and plasmonic devices would open new chapters in functional optics. They can manipulate the electromagnetic waves in unprecedented forms and realize powerful applications like invisibility cloaking, sub wavelength imaging, transformation optics and functional sensors etc. This review focused on the recent development in soft, flexible metamaterials and plasmonics that resonate from microwave to visible frequencies, various applications have been realized in filters, sensors and surface enhanced Raman spectroscopy etc. Optical structure designs are ranged from split ring resonators, multilayer fishnet metamaterials and nanoparticle arrays. Common soft substrates include polyimide, polydimethysiloxane, polyethylene terephthalate and polyethylene naphthalene. Their mechanical and optical properties were discussed. Compatible fabrication techniques such as conventional photolithography, electron beam lithography and a few newly developed nanofabrication techniques were introduced. Among which, nanoimprint and nanotransfer techniques that result in large area, low cost, high quality soft metamaterials and plasmonics are promising in wearable and tunable applications.
author_names: Li Gao

Bingwei Lu

Hangxun Xu
title: Materials and applications of flexible metamaterials and plasmonics
year: 2016

abstract: We fabricate quasi three dimensional terahertz electric metamaterials by stacking multiple single layer planar metamaterials fabricated on thin, flexible polyimide substrates. Terahertz time domain spectroscopy is used to characterize their transmission properties, with which we obtain the frequency dependent complex effective dielectric functions. Increasing the number of layers reduces the resonant transmission minimum, while the extracted effective dielectric functions are independent on the number of layers. The results reveal that the real portions of the dielectric functions only show positive values, however, decreasing the thickness of the polyimide substrates, and thereby the spacing between the adjacent split ring resonator layers, enables negative electric response.
author_names: Abul Kalam Azad

Hou-Tong Chen

Xinchao Lu

Jianqiang Gu

Elshan A Akhadov

Antoinette J Taylor

Weili Zhang
title: Flexible Quasi Three Dimensional Terahertz Electric Metamaterials
year: 2009