Abstract-All-metal terahertz metamaterial biosensor for protein detection

 

Gangqi Wang, Fengjie Zhu, Tingting Lang, Jianjun Liu, Zhi Hong,  Jianyuan Qin 

https://nanoscalereslett.springeropen.com/articles/10.1186/s11671-021-03566-3

In this paper, a terahertz (THz) biosensor based on all-metal metamaterial is theoretically investigated and experimentally verified. This THz metamaterial biosensor uses stainless steel materials that are manufactured via laser-drilling technology. The simulation results show that the maximum refractive index sensitivity and the figure of merit of this metamaterial sensor are 294.95 GHz/RIU and 4.03, respectively. Then, bovine serum albumin was chosen as the detection substance to assess this biosensor’s effectiveness. The experiment results show that the detection sensitivity is 72.81 GHz/(ng/mm2) and the limit of detection is 0.035 mg/mL. This THz metamaterial biosensor is simple, cost-effective, easy to fabricate, and has great potential in various biosensing applications.

Abstract-Improvement of Wide-Angle Response for Terahertz Carpet Cloaking by Using a Metasurface with Multilayer Microstructure

Meng Li, Shuang Han, Haiyong Gan, Chenxia Li, Jianjun Liu, Zhi Hong, Xufeng Jing, 

https://link.springer.com/article/10.1007%2Fs10762-019-00617-w

A metasurface provides a completely new path to realize a cloaking effect by using phase compensation. However, the traditional invisible cloaks by using metasurfaces are limited at the narrow bandwidth and angle response. Here, we propose a multilayer metasurface to construct a cloak device, and more geometric freedom ensures the broadband and wide-angle response of our designed cloak. The invisible effect is revealed by near-field and far-field distribution for the ground plane, bare bump, and cloak, respectively. Our designed cloaking with the metasurface composed of five-layer unit cell structure has a good invisible effect at the broadband range from 0.7 to 0.8 THz and has a wide-angle response from 35 to 50°.

Abstract-Structure and spectroscopic characterization of pharmaceutical co-crystal formation between acetazolamide and 4-hydroxybenzoic acid

Yaguo Wang, Jiadan Xue, Jianyuan Qin, Jianjun Liu, Yong Du

https://www.sciencedirect.com/science/article/pii/S138614251930469X

Co-crystals have great potential for drug research and development because the formation of co-crystal is accompanied by changes inter-molecular interactions between starting materials that enable to improve both physical and chemical properties of active pharmaceutical ingredients. In order to provide a more profound insight into the structural changes of specific drugs upon co-crystallization, spectroscopic characterization of solid-state acetazolamide (ACZ), 4-hydroxybenzoic acid (4HBA) and their co-crystal prepared by mechanical grinding approach has been performed with spectral techniques including terahertz time-domain spectroscopy (THz-TDS) and Raman spectroscopy. Experimental THz spectra show that the ACZ-4HBA co-crystal has a few significantly different absorption peaks in 0.82, 1.16, 1.28 and 1.64 THz respectively compared with parent materials in the frequency region from 0.2 to 1.8 THz. Likewise, such differences between the co-crystal and starting compounds could also be characterized by Raman vibrational spectra. Moreover, density functional theory (DFT) calculations were performed to simulate structures and vibrational modes of three kind of possible co-crystal theoretical forms (form I, II and III) between ACZ and 4HBA. Theoretical results and THz/Raman vibrational spectra of ACZ-4HBA co-crystal show that the 4HBA links to the thiadiazole acetamide fragment of ACZ via the double-bridged heterodimeric synthon C(N)NH⋯HOOC inter-molecular hydrogen bonding interaction establishing the theoretical form I, which is more consistent with experimental observations than other two co-crystal forms. These results provide rich information and unique method for characterizing the composition of co-crystal structures and also inter-molecular interactions shown within pharmaceutical co-crystallization process at the molecular level.

Abstract-Guided mode resonance in terahertz compound metamaterial waveguides

Jianjun Liu, Hang Chen, Xufeng Jing, Zhi Hong


https://www.sciencedirect.com/science/article/pii/S0030402618311148

Guided mode resonances (GMR) in a planar compound metamaterial (MM) consisting of two square closed ring resonators were numerically calculated and experimentally demonstrated. The strength and bandwidth of the GMR can be controlled by changing the distance between the two square rings. Moreover, asymmetric Fano resonance or electromagnetic induced transparency (EIT) was realized by manipulating the interaction between the GMR and the dipolar resonance of the MM. The measured results at terahertz frequencies are in good agreement with simulations

Abstract-Application of terahertz spectroscopy and chemometrics for discrimination of transgenic camellia oil

Jianjun Liu, Lanlan Fan, Yuanming Liu, Lili Mao, Jianquan Kan,

PLS-WLDA, an alternative method, is performed on terahertz spectra data. The identification result of PLS-WLDA of terahertz spectra using different preprocessing type (raw, offset and derivative), it is possible to correctly identify 97% of all samples set. Compared with the SPA-WLDA, PLS-WLDA has the better discrimination performance. However, in the aspect of robustness, SPA–WLDA is better than PLS-WLDA.

https://www.sciencedirect.com/science/article/pii/S1386142518307753

Discrimination of transgenic edible oil has become the focus of attention in the field of food safety. In this paper, we propose a method for discrimination of transgenic edible oils by using terahertz spectroscopy combine with weighted linear discriminant analysis (WLDA). To evaluate the lustiness of the model, we employ successive projection arithmetic (SPA) and partial least squares (PLS) to verify the discrimination performance through variable selection. The results demonstrate that the SPA-WLDA model has higher classification accuracy than PLS-WLDA. In conclusion, terahertz spectroscopy is coupled with chemometrics is an effective method for discriminating various types of transgenic edible oils.

Abstract-Mechanically tunable dual frequency THz metamaterial filter

Jianjun Liu, Zhi Hong,

https://www.sciencedirect.com/science/article/pii/S0030401818305108

A mechanically tunable dual frequency THz metamaterial (MM) filter is proposed in this paper. The filter is composed of two individual U-shaped MMs separated by a certain distance. The resonance frequencies can be tuned by adjusting the relative position of the two MMs using mechanical method. The simulation results show that the filter has two tunable resonant frequencies, and the relative tunable ranges are 50.8% from 0.285 THz to 0.43 THz, and 71.0% from 0.496 THz to 0.848 THz, respectively. In addition, through the coordination of two adjustment dimensions, independently tuning of one resonance frequency of the filter can be realized while keeping another resonance unchanged.

Abstract-Broadband polarization-independent two-dimensionally isotropic ultrahigh index metamaterials

Xincui Gui, Xufeng Jing, Jianjun Liu, Pengwei Zhou, Zhi Hong,

https://www.sciencedirect.com/science/article/pii/S1350449517305637

By drastically decreasing the diamagnetic effect with a thin window type structure in the unit cell and increasing the effective permittivity through strong capacitive coupling, we report a window-type broadband isotropic two-dimensional metamaterial with extremely high refractive index in the terahertz region. The designed peak index of refraction of near 18.22 at about 1.15 THz is predicted. In the experiment, we fabricated a “window” type structural metamaterial, and the measured transmission was compared with the results of the simulation. The effective refractive index for the prepared metamaterial was extracted by S-parameter extraction method. It is found that ultrahigh refractive index metamaterials depend on the electric field coupling effect, the magnetic field diamagnetic response, and the geometric parameters in the unit cell. Higher resonant frequency makes it possible to utilize broader high refractive index with low loss and large transmission.

Abstract-Terahertz spectroscopy detection of genetically modified sugar beets containing the Xa21 gene based on chemometrics methods

Jianjun Liu

https://www.osapublishing.org/jot/abstract.cfm?uri=jot-83-10-627&origin=search

Because traditional detection of genetically modified organisms (GMOs) has the disadvantages of being costly, time consuming, and awkward to perform, a novel method for the detection of GMOs based on terahertz spectroscopy combined with chemometrics methods is proposed. In this work, terahertz spectrum data of a genetically modified sugar beet and its parents are pretreated by using principal component analysis and then using the weighted discriminant analysis model, which is an improved discriminant analysis that applys a weighted algorithm to the detection of a genetically modified sugar beet and its parents. It is found from the experimental results that the samples are expressed by the zonation of saline minerals. By analyzing this phenomenon, it is easy to identify these genetically modified sugar beets. By combining terahertz spectroscopy with chemometrics methods, this paper provides a precise, fast, convenient, and nondestructive method for the detection of GMOs.

© 2017 Optical Society of America

Abstract-Experimental realization of perfect terahertz plasmonic absorbers using highly doped silicon substrate and CMOS-compatible techniques

Ting Wang, Su Shen, Jianjun Liu, Yusheng Zhang, and Zhanghua Han
https://www.osapublishing.org/ome/abstract.cfm?uri=ome-6-2-523

We experimentally demonstrate that at terahertz frequencies perfect plasmonic absorbers made on a highly doped silicon platform can be easily realized, exhibiting near-zero dips in the reflection spectra. The unit cell of the absorber consists of a dielectric layer of SiO2 film sandwiched between a highly doped silicon wafer and the copper structures, in the form of either one-dimensional stripe array or two-dimensional cross array. The reflection spectrum of the proposed absorbers are characterized using a terahertz time-domain spectroscopy system and the experimental results are in good agreement with numerical simulations. The dependence of the absorption on the THz polarization for both the 1D and 2D absorbers are also investigated. The high performance together with the easy fabrication processes presented in this paper show that the plasmonic absorber holds high prospect in terahertz applications.

© 2016 Optical Society of America

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Abstract-Absorber: a novel terahertz sensor in the application of substance identification

·       Jianjun Liu , Lanlan Fa, Jinfeng Ku, Lili Mao

    http://link.springer.com/article/10.1007/s11082-015-0361-5?no-access=true

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Different to traditional identification methods, a novel method that using terahertz absorber to identify waste oil and edible oil is proposed in this paper. Terahertz absorber is a sensitive metamaterials sensor which be characteristic of low and frequency in the terahertz frequency band. When the waste oil or edible oil is added to the absorber void, terahertz electromagnetic response of absorber is moved, and the redshift phenomenon of response peak is produced. Comparison of different levels of redshift, we can distinguish waste oil and edible oil clearly. The experimental data and results show that the proposed method provides a novel detection method for different substance by using metamaterials sensor in terahertz band.

Abstract-Terahertz broadband polarizer using bilayer subwavelength metal wire-grid structure on polyimide film

Xiao Wu  Huayue Li   Shixiong Liang   Jianjun Liu  Zhanghua Han  Zhi Hong 

http://www.opticsjournal.net/abstract.htm?aid=OJ1412290000238EaHdJ

A terahertz (THz) broadband polarizer using bilayer subwavelength metal wire-grid structure on both sides of polyimide film is simulated by the finite-difference time-domain method. We analyze the effect of film -thickness, material loss, and lateral shift between two metallic gratings on the performance of the THz -polarizer. Bilayer wire-grid polarizers are fabricated by a simple way of laser induced and non-electrolytic plating with copper. The THz time-domain spectroscopy measurements show that in 0.2–1.6 THz frequency range, the extinction ratio is better than 45 dB, the average extinction ratio reaches 53 dB, and the -transmittance exceeds 67%, which shows great advantage over conventional single wire-grid THz polarizer.

Abstract-The terahertz spectrum detection of transgenic food

• Jianjun Liu^a, , 
• Zhi Li^a, b

• ^a School of Mechano-Electronic Engineering, Xidian University, Xi’an, Shanxi 710071, PR China
• ^b School of Electronic Engineering and Automation, Guilin University of Electronic Technology, Guilin, Guangxi 541004, PR China

http://www.sciencedirect.com/science/article/pii/S0030402614011139

Received 13 July 2013, Accepted 5 January 2014, Available online 4 November 2014

This paper presents the optical characteristic of the four transgenic foods in the terahertz (THz) by means of electro-optic sampling. The transmission spectra and complex refractive index of the four transgenic foods are obtained. This paper finds that transgenic maize (TGM), transgenic rice (TGR), transgenic soybean (TGS) and transgenic potato (TGP) all have absorption within the frequency range of 0.2 and 2.5 THz. It can be seen that the TGM and TGR have obvious absorption peaks at 1.08 and 1.82 THz respectively, the TGS has a plurality of absorption peak in this frequency band, compared to the other three samples, and the TGP is slow. The unique absorption properties in THz of four transgenic foods show that the time-resolved terahertz spectroscopy can be applied to detect and identify transgenic food.

Abstract-Terahertz gas sensing based on a simple one-dimensional photonic crystal cavity with high-quality factors

Tao Chen, Zhanghua Han, Jianjun Liu, and Zhi Hong  »View Author Affiliations

Applied Optics, Vol. 53, Issue 16, pp. 3454-3458 (2014)
http://dx.doi.org/10.1364/AO.53.003454

http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-53-16-3454

We report in this paper terahertz gas sensing using a simple 1D photonic crystal cavity. The resonant frequencies of the cavity depend linearly on the refractive index of the ambient gas, which can then be measured by monitoring the resonance shift. Although quite easy to manufacture, this cavity exhibits high-quality factors, facilitating the realization of high sensitivity in the gas refractive index sensing. In our experiment, 6% of the change of hydrogen concentration in air, which corresponds to a refractive index change of 1.4×10−5, can be steadily detected, and different gas samples can be easily identified. Our experimental results are consistent with the theoretically calculated spectral responses of the cavity using the transfer matrix method.

© 2014 Optical Society of America