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841 KiB

Open AccessArticle

Research on the Design of an Optical Information Storage Sensing System Using a Diffractive Optical Element

by Xuemin Cheng, Qun Hao, Jianbo Hou, Xiangping Li, Jianshe Ma and Min Gu

Sensors 2013, 13(11), 15409-15421; https://doi.org/10.3390/s131115409 - 8 Nov 2013

Cited by 2 | Viewed by 7123

Abstract

This paper introduces a compact optical information storage sensing system. Applications of this system include longitudinal surface plasmon resonance detection of gold nanorods with a single femtosecond laser in three-dimensional space as well as data storage. A diffractive optical element (DOE) is applied [...] Read more.

This paper introduces a compact optical information storage sensing system. Applications of this system include longitudinal surface plasmon resonance detection of gold nanorods with a single femtosecond laser in three-dimensional space as well as data storage. A diffractive optical element (DOE) is applied in the system to separate the recording-reading beam from the servo beam. This allows us to apply a single laser and one objective lens in a single optical path for the servo beam and the recording-reading beam. The optical system has a linear region of 8 λ, which is compatible with current DVD servo modules. The wavefront error of the optical system is below 0.03 λ_rms. The minimum grating period of the DOE is 13.4 µm, and the depth of the DOE is 1.2 µm, which makes fabrication of it possible. The DOE is also designed to conveniently control the layer-selection process, as there is a linear correlation between the displacement of the DOE and the layer-selection distance. The displacement of DOE is in the range of 0–6.045 mm when the thickness of the layer-selection is 0.3 mm. Experiments were performed and the results have been verified. Full article

(This article belongs to the Special Issue Nanotube and Nanowire Sensors)

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614 KiB

Open AccessArticle

Development of Anodic Titania Nanotubes for Application in High Sensitivity Amperometric Glucose and Uric Acid Biosensors

by Hsiang-Ching Lee, Li-Fan Zhang, Jyh-Ling Lin, Yuan-Lung Chin and Tai-Ping Sun

Sensors 2013, 13(10), 14161-14174; https://doi.org/10.3390/s131014161 - 21 Oct 2013

Cited by 15 | Viewed by 8032

Abstract

The purpose of this study was to develop novel nanoscale biosensors using titania nanotubes (TNTs) made by anodization. Titania nanotubes were produced on pure titanium sheets by anodization at room temperature. In this research, the electrolyte composition ethylene glycol 250 mL/NH₄F [...] Read more.

The purpose of this study was to develop novel nanoscale biosensors using titania nanotubes (TNTs) made by anodization. Titania nanotubes were produced on pure titanium sheets by anodization at room temperature. In this research, the electrolyte composition ethylene glycol 250 mL/NH₄F 1.5 g/DI water 20 mL was found to produce the best titania nanotubes array films for application in amperometric biosensors. The amperometric results exhibit an excellent linearity for uric acid (UA) concentrations in the range between 2 and 14 mg/dL, with 23.3 (µA·cm⁻²)·(mg/dL)⁻¹ UA sensitivity, and a correlation coefficient of 0.993. The glucose biosensor presented a good linear relationship in the lower glucose concentration range between 50 and 125 mg/dL, and the corresponding sensitivity was approximately 249.6 (µA·cm⁻²)·(100 mg/dL)⁻¹ glucose, with a correlation coefficient of 0.973. Full article

(This article belongs to the Special Issue Nanotube and Nanowire Sensors)

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800 KiB

Open AccessArticle

Direct Electrochemistry of Hemoglobin Immobilized on a Functionalized Multi-Walled Carbon Nanotubes and Gold Nanoparticles Nanocomplex-Modified Glassy Carbon Electrode

by Jun Hong, Ying-Xue Zhao, Bao-Lin Xiao, Ali Akbar Moosavi-Movahedi, Hedayatollah Ghourchian and Nader Sheibani

Sensors 2013, 13(7), 8595-8611; https://doi.org/10.3390/s130708595 - 5 Jul 2013

Cited by 47 | Viewed by 9928

Abstract

Direct electron transfer of hemoglobin (Hb) was realized by immobilizing Hb on a carboxyl functionalized multi-walled carbon nanotubes (FMWCNTs) and gold nanoparticles (AuNPs) nanocomplex-modified glassy carbon electrode. The ultraviolet-visible absorption spectrometry (UV-Vis), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) methods were [...] Read more.

Direct electron transfer of hemoglobin (Hb) was realized by immobilizing Hb on a carboxyl functionalized multi-walled carbon nanotubes (FMWCNTs) and gold nanoparticles (AuNPs) nanocomplex-modified glassy carbon electrode. The ultraviolet-visible absorption spectrometry (UV-Vis), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) methods were utilized for additional characterization of the AuNPs and FMWCNTs. The cyclic voltammogram of the modified electrode has a pair of well-defined quasi-reversible redox peaks with a formal potential of −0.270 ± 0.002 V (vs. Ag/AgCl) at a scan rate of 0.05 V/s. The heterogeneous electron transfer constant (ks) was evaluated to be 4.0 ± 0.2 s⁻¹. The average surface concentration of electro-active Hb on the surface of the modified glassy carbon electrode was calculated to be 6.8 ± 0.3 × 10⁻¹⁰ mol cm⁻². The cathodic peak current of the modified electrode increased linearly with increasing concentration of hydrogen peroxide (from 0.05 nM to 1 nM) with a detection limit of 0.05 ± 0.01 nM. The apparent Michaelis-Menten constant (K_m^app) was calculated to be 0.85 ± 0.1 nM. Thus, the modified electrode could be applied as a third generation biosensor with high sensitivity, long-term stability and low detection limit. Full article

(This article belongs to the Special Issue Nanotube and Nanowire Sensors)

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645 KiB

Open AccessArticle

A Wireless Monitoring Sub-nA Resolution Test Platform for Nanostructure Sensors

by Chi Woong Jang, Young Tae Byun, Taikjin Lee, Deok Ha Woo, Seok Lee and Young Min Jhon

Sensors 2013, 13(6), 7827-7837; https://doi.org/10.3390/s130607827 - 19 Jun 2013

Cited by 3 | Viewed by 6272

Abstract

We have constructed a wireless monitoring test platform with a sub-nA resolution signal amplification/processing circuit (SAPC) and a wireless communication network to test the real-time remote monitoring of the signals from carbon nanotube (CNT) sensors. The operation characteristics of the CNT sensors can [...] Read more.

We have constructed a wireless monitoring test platform with a sub-nA resolution signal amplification/processing circuit (SAPC) and a wireless communication network to test the real-time remote monitoring of the signals from carbon nanotube (CNT) sensors. The operation characteristics of the CNT sensors can also be measured by the I_SD-V_SD curve with the SAPC. The SAPC signals are transmitted to a personal computer by Bluetooth communication and the signals from the computer are transmitted to smart phones by Wi-Fi communication, in such a way that the signals from the sensors can be remotely monitored through a web browser. Successful remote monitoring of signals from a CNT sensor was achieved with the wireless monitoring test platform for detection of 0.15% methanol vapor with 0.5 nA resolution and 7 Hz sampling rate. Full article

(This article belongs to the Special Issue Nanotube and Nanowire Sensors)

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565 KiB

Open AccessArticle

Highly Specific and Cost-Efficient Detection of Salmonella Paratyphi A Combining Aptamers with Single-Walled Carbon Nanotubes

by Ming Yang, Zhihui Peng, Yi Ning, Yongzhe Chen, Qin Zhou and Le Deng

Sensors 2013, 13(5), 6865-6881; https://doi.org/10.3390/s130506865 - 22 May 2013

Cited by 98 | Viewed by 11225

Abstract

In this paper, a panel of single-stranded DNA aptamers with high affinity and specificity against Salmonella Paratyphi A was selected from an enriched oligonucleotide pool by a whole-cell-Systematic Evolution of Ligands by Exponential Enrichment (SELEX) procedure, during which four other Salmonella serovars were [...] Read more.

In this paper, a panel of single-stranded DNA aptamers with high affinity and specificity against Salmonella Paratyphi A was selected from an enriched oligonucleotide pool by a whole-cell-Systematic Evolution of Ligands by Exponential Enrichment (SELEX) procedure, during which four other Salmonella serovars were used as counter-selection targets. It was determined through a fluorescence assay that the selected aptamers had high binding ability and specificity to this pathogen. The dissociation constant of these aptamers were up to nanomolar range, and aptamer Apt22 with the lowest K_d (47 ± 3 nM) was used in cell imaging experiments. To detect this bacteria with high specificity and cost-efficiently, a novel useful detection method was also constructed based on the noncovalent self-assembly of single-walled carbon nanotubes (SWNTs) and DNAzyme-labeled aptamer detection probes. The amounts of target bacteria could be quantified by exploiting chemoluminescence intensity changes at 420 nm and the detection limit of the method was 10³ cfu/mL. This study demonstrated the applicability of Salmonella specific aptamers and their potential for use in the detection of Salmonella in food, clinical and environmental samples. Full article

(This article belongs to the Special Issue Nanotube and Nanowire Sensors)

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928 KiB

Open AccessArticle

Hydrothermal Synthesis of Various Hierarchical ZnO Nanostructures and Their Methane Sensing Properties

by Qu Zhou, Weigen Chen, Lingna Xu and Shudi Peng

Sensors 2013, 13(5), 6171-6182; https://doi.org/10.3390/s130506171 - 10 May 2013

Cited by 94 | Viewed by 10601

Abstract

Hierarchical flower-like ZnO nanorods, net-like ZnO nanofibers and ZnO nanobulks have been successfully synthesized via a surfactant assisted hydrothemal method. The synthesized products were characterized by X-ray powder diffraction and field emission scanning electron microscopy, respectively. A possible growth mechanism of the various [...] Read more.

Hierarchical flower-like ZnO nanorods, net-like ZnO nanofibers and ZnO nanobulks have been successfully synthesized via a surfactant assisted hydrothemal method. The synthesized products were characterized by X-ray powder diffraction and field emission scanning electron microscopy, respectively. A possible growth mechanism of the various hierarchical ZnO nanostructures is discussed in detail. Gas sensors based on the as-prepared ZnO nanostructures were fabricated by screen-printing on a flat ceramic substrate. Furthermore, their gas sensing characteristics towards methane were systematically investigated. Methane is an important characteristic hydrocarbon contaminant found dissolved in power transformer oil as a result of faults. We find that the hierarchical flower-like ZnO nanorods and net-like ZnO nanofibers samples show higher gas response and lower operating temperature with rapid response-recovery time compared to those of sensors based on ZnO nanobulks. These results present a feasible way of exploring high performance sensing materials for on-site detection of characteristic fault gases dissolved in transformer oil. Full article

(This article belongs to the Special Issue Nanotube and Nanowire Sensors)

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429 KiB

Open AccessArticle

Simple Fabrication Process for 2D ZnO Nanowalls and Their Potential Application as a Methane Sensor

by Tse-Pu Chen, Sheng-Po Chang, Fei-Yi Hung, Shoou-Jinn Chang, Zhan-Shuo Hu and Kuan-Jen Chen

Sensors 2013, 13(3), 3941-3950; https://doi.org/10.3390/s130303941 - 20 Mar 2013

Cited by 61 | Viewed by 8368

Abstract

Two-dimensional (2D) ZnO nanowalls were prepared on a glass substrate by a low-temperature thermal evaporation method, in which the fabrication process did not use a metal catalyst or the pre-deposition of a ZnO seed layer on the substrate. The nanowalls were characterized for [...] Read more.

Two-dimensional (2D) ZnO nanowalls were prepared on a glass substrate by a low-temperature thermal evaporation method, in which the fabrication process did not use a metal catalyst or the pre-deposition of a ZnO seed layer on the substrate. The nanowalls were characterized for their surface morphology, and the structural and optical properties were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL). The fabricated ZnO nanowalls have many advantages, such as low growth temperature and good crystal quality, while being fast, low cost, and easy to fabricate. Methane sensor measurements of the ZnO nanowalls show a high sensitivity to methane gas, and rapid response and recovery times. These unique characteristics are attributed to the high surface-to-volume ratio of the ZnO nanowalls. Thus, the ZnO nanowall methane sensor is a potential gas sensor candidate owing to its good performance. Full article

(This article belongs to the Special Issue Nanotube and Nanowire Sensors)

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576 KiB

Open AccessArticle

C₅₉N Peapods Sensing the Temperature

by Yongfeng Li, Toshiro Kaneko and Rikizo Hatakeyama

Sensors 2013, 13(1), 966-974; https://doi.org/10.3390/s130100966 - 15 Jan 2013

Cited by 4 | Viewed by 6021

Abstract

We report the novel photoresponse of nanodevices made from azafullerene (C₅₉N)-encapsulated single-walled carbon nanotubes (C₅₉N@SWNTs), so called peapods. The photoconducting properties of a C₅₉N@SWNT are measured over a temperature range of 10 to 300 K under a [...] Read more.

We report the novel photoresponse of nanodevices made from azafullerene (C₅₉N)-encapsulated single-walled carbon nanotubes (C₅₉N@SWNTs), so called peapods. The photoconducting properties of a C₅₉N@SWNT are measured over a temperature range of 10 to 300 K under a field-effect transistor configuration. It is found that the photosensitivity of C₅₉N@SWNTs depends very sensitively on the temperature, making them an attractive candidate as a component of nanothermometers covering a wide temperature range. Our results indicate that it is possible to read the temperature by monitoring the optoelectronics signal of C₅₉N@SWNTs. In particular, sensing low temperatures would become more convenient and easy by giving a simple light pulse. Full article

(This article belongs to the Special Issue Nanotube and Nanowire Sensors)

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Review

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967 KiB

Open AccessReview

Integration of Metal Oxide Nanowires in Flexible Gas Sensing Devices

by Elisabetta Comini

Sensors 2013, 13(8), 10659-10673; https://doi.org/10.3390/s130810659 - 15 Aug 2013

Cited by 31 | Viewed by 8630

Abstract

Metal oxide nanowires are very promising active materials for different applications, especially in the field of gas sensors. Advances in fabrication technologies now allow the preparation of nanowires on flexible substrates, expanding the potential market of the resulting sensors. The critical steps for [...] Read more.

Metal oxide nanowires are very promising active materials for different applications, especially in the field of gas sensors. Advances in fabrication technologies now allow the preparation of nanowires on flexible substrates, expanding the potential market of the resulting sensors. The critical steps for the large-scale preparation of reliable sensing devices are the elimination of high temperatures processes and the stretchability of the entire final device, including the active material. Direct growth on flexible substrates and post-growth procedures have been successfully used for the preparation of gas sensors. The paper will summarize the procedures used for the preparation of flexible and wearable gas sensors prototypes with an overlook of the challenges and the future perspectives concerning this field. Full article

(This article belongs to the Special Issue Nanotube and Nanowire Sensors)

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1238 KiB

Open AccessReview

Spectroscopy, Manipulation and Trapping of Neutral Atoms, Molecules, and Other Particles Using Optical Nanofibers: A Review

by Michael J. Morrissey, Kieran Deasy, Mary Frawley, Ravi Kumar, Eugen Prel, Laura Russell, Viet Giang Truong and Síle Nic Chormaic

Sensors 2013, 13(8), 10449-10481; https://doi.org/10.3390/s130810449 - 13 Aug 2013

Cited by 79 | Viewed by 14184

Abstract

The use of tapered optical fibers, i.e., optical nanofibers, for spectroscopy and the detection of small numbers of particles, such as neutral atoms or molecules, has been gaining interest in recent years. In this review, we briefly introduce the optical nanofiber, its [...] Read more.

The use of tapered optical fibers, i.e., optical nanofibers, for spectroscopy and the detection of small numbers of particles, such as neutral atoms or molecules, has been gaining interest in recent years. In this review, we briefly introduce the optical nanofiber, its fabrication, and optical mode propagation within. We discuss recent progress on the integration of optical nanofibers into laser-cooled atom and vapor systems, paying particular attention to spectroscopy, cold atom cloud characterization, and optical trapping schemes. Next, a natural extension of this work to molecules is introduced. Finally, we consider several alternatives to optical nanofibers that display some advantages for specific applications. Full article

(This article belongs to the Special Issue Nanotube and Nanowire Sensors)

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