scholarly journals Electrical Conductivity and Optical Properties of Nanoscale Titanium Films on Sapphire for Localized Plasmon Resonance-Based Sensors

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1165
Author(s):  
Klavdiya Korotkova ◽  
Dashi Bainov ◽  
Serafim Smirnov ◽  
Igor Yunusov ◽  
Yury Zhidik

The developing area of plasmonics has led to the possibility of creating a new type of high-speed, high-sensitivity optical sensor for biological environment analysis. The functional layer of such biosensors are nanoscale films of noble metals. In this work we suggest using a thin film of titanium as a functional layer. This paper presents the results of the research on electrical and optical characteristics of 5 to 80 nm thick titanium films deposited on sapphire substrates by magnetron sputtering. It is shown that surface plasmon resonance is consistently observed in the investigated titanium films and the theoretical grounds of surface plasmon resonance excitement is given. In structures with titanium films less than 15 nm thick, local plasmon resonance is observed along with surface plasmon resonance. Local plasmon resonance is more sensitive to the surface state of a thin film of titanium, which on the one hand increases the sensitivity of a biosensor, and on the other hand imposes restrictions on the parameters of nanoscale films.

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1003 ◽  
Author(s):  
Jin-Ha Choi ◽  
Jin-Ho Lee ◽  
Joohyung Son ◽  
Jeong-Woo Choi

For the early diagnosis of several diseases, various biomarkers have been discovered and utilized through the measurement of concentrations in body fluids such as blood, urine, and saliva. The most representative analytical method for biomarker detection is an immunosensor, which exploits the specific antigen-antibody immunoreaction. Among diverse analytical methods, surface plasmon resonance (SPR)-based immunosensors are emerging as a potential detection platform due to high sensitivity, selectivity, and intuitive features. Particularly, SPR-based immunosensors could detect biomarkers without labeling of a specific detection probe, as typical immunosensors such as enzyme-linked immunosorbent assay (ELISA) use enzymes like horseradish peroxidase (HRP). In this review, SPR-based immunosensors utilizing noble metals such as Au and Ag as SPR-inducing factors for the measurement of different types of protein biomarkers, including viruses, microbes, and extracellular vesicles (EV), are briefly introduced.


2019 ◽  
Vol 61 (1) ◽  
Author(s):  
Shahab Bayani Ahangar ◽  
Vinaykumar Konduru ◽  
Jeffrey S. Allen ◽  
Nenad Miljkovic ◽  
Seong Hyuk Lee ◽  
...  

Abstract This paper describes the fabrication and testing of a novel angle-scanning surface plasmon resonance imaging (SPRi) instrument. The combination of two stationary mirrors and two angle-controlled mirrors provides high accuracy (up to 10−3°) and high-speed angular probing. This instrument minimizes the angle-dependent image artifact that arises due to beam walk, which is the biggest challenge for the use of SPRi with angular modulation (AM). In the work described in this paper, two linear stages were employed to minimize the image artifact by adjusting the location of the angle-controlled mirrors and the camera. The SPRi instrument was used to visualize coalescence during dropwise condensation. The results show that the effect of the environment’s temperature on reflectance was less than 1% when the incident angle was carefully chosen for SPRi with intensity modulation (IM). This means that condensation visualization can be carried out at ambient temperatures, without the need for a Peltier stage or a thermally controlled condensing surface. The concept of pixel neighboring was employed to assess the probability of noise and the standard error of thin film measurement. Experimental analyses during dropwise condensation show (1) the presence of a thin film with thickness of one monolayer, and (2) surface coverage of 0.71 m2/m2 by the thin film in the area between the droplets. In addition, analyses showed the existence of a dry area at the part of the substrate exposed by coalescence to ambient air. The results of this work undermine the validity of the film rupture theory as the dropwise condensation mechanism. Graphic abstract


PIERS Online ◽  
2008 ◽  
Vol 4 (7) ◽  
pp. 746-750 ◽  
Author(s):  
Bing-Hung Chen ◽  
Yih-Chau Wang ◽  
Jia-Hng Lin

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1325 ◽  
Author(s):  
Ru-Jing Sun ◽  
Hung Ji Huang ◽  
Chien-Nan Hsiao ◽  
Yu-Wei Lin ◽  
Bo-Huei Liao ◽  
...  

A TiN-based substrate with high reusability presented high-sensitivity refractive index measurements in a home-built surface plasmon resonance (SPR) heterodyne phase interrogation system. TiN layers with and without additional inclined-deposited TiN (i-TiN) layers on glass substrates reached high bulk charge carrier densities of 1.28 × 1022 and 1.91 × 1022 cm−3, respectively. The additional 1.4 nm i-TiN layer of the nanorod array presented a detection limit of 6.1 × 10−7 RIU and was higher than that of the 46 nm TiN layer at 1.2 × 10−6 RIU when measuring the refractive index of a glucose solution. Furthermore, the long-term durability of the TiN-based substrate demonstrated by multiple processing experiments presented a high potential for various practical sensing applications.


2021 ◽  
Vol 11 (7) ◽  
pp. 2963
Author(s):  
Nur Alia Sheh Omar ◽  
Yap Wing Fen ◽  
Irmawati Ramli ◽  
Umi Zulaikha Mohd Azmi ◽  
Hazwani Suhaila Hashim ◽  
...  

A novel vanadium–cellulose composite thin film-based on angular interrogation surface plasmon resonance (SPR) sensor for ppb-level detection of Ni(II) ion was developed. Experimental results show that the sensor has a linear response to the Ni(II) ion concentrations in the range of 2–50 ppb with a determination coefficient (R2) of 0.9910. This SPR sensor can attain a maximum sensitivity (0.068° ppb−1), binding affinity constant (1.819 × 106 M−1), detection accuracy (0.3034 degree−1), and signal-to-noise-ratio (0.0276) for Ni(II) ion detection. The optical properties of thin-film targeting Ni(II) ions in different concentrations were obtained by fitting the SPR reflectance curves using the WinSpall program. All in all, the proposed Au/MPA/V–CNCs–CTA thin-film-based surface plasmon resonance sensor exhibits better sensing performance than the previous film-based sensor and demonstrates a wide and promising technology candidate for environmental monitoring applications in the future.


Sign in / Sign up

Export Citation Format

Share Document