Research

12 pages, 2295 KiB

Open AccessArticle

A Motion-Balanced Sensor Based on the Triboelectricity of Nano-Iron Suspension and Flexible Polymer

by Zhihua Wang, Songyi Yang, Shuang Miao, Qiongfeng Shi, Tianyiyi He and Chengkuo Lee

Nanomaterials 2019, 9(5), 690; https://doi.org/10.3390/nano9050690 - 02 May 2019

Cited by 9 | Viewed by 3048

With the development of the Internet of Things and information technology, a large number of inexpensive sensors are needed to monitor the state of the object. A wide variety of sensors with a low cost can be made using the difference in charge [...] Read more.

With the development of the Internet of Things and information technology, a large number of inexpensive sensors are needed to monitor the state of the object. A wide variety of sensors with a low cost can be made using the difference in charge attractiveness between flexible polymers and other materials. Compared to the two solid materials, a sensor made of a solid polymer-liquid has a large contact area and low friction. A motion-balanced sensor is presented based on the polytetrafluoroethene pipe and nano-iron suspension. The effect of the concentration and volume of the nano-iron suspension on the output voltage of the sensor is analyzed. The motion-balanced sensor can be used to measure the tilt angle of the object and there is a linear relationship between the output voltage and the tilt angle. A comparison test is performed to a commercial acceleration sensor with PZT-5. The test results show that the frequency characteristics and amplitude characteristics of the motion-balanced sensor are consistent with those of the acceleration sensor. The motion-balanced sensor can be used to determine the state of exercise such as walking, running, etc. The motion-balanced sensor has broad application prospects for monitoring the bridges and power towers balance, stroke patients’ health assessment, etc. Full article

(This article belongs to the Special Issue From Nanomaterials to Intelligent Nanosystems)

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12 pages, 3102 KiB

Open AccessArticle

Unidirectional Enhanced Dipolar Emission with an Individual Dielectric Nanoantenna

by Tianyue Zhang, Jian Xu, Zi-Lan Deng, Dejiao Hu, Fei Qin and Xiangping Li

Nanomaterials 2019, 9(4), 629; https://doi.org/10.3390/nano9040629 - 18 Apr 2019

Cited by 16 | Viewed by 4656

Abstract

Light manipulation at the nanoscale is the vanguard of plasmonics. Controlling light radiation into a desired direction in parallel with high optical signal enhancement is still a challenge for designing ultracompact nanoantennas far below subwavelength dimensions. Here, we theoretically demonstrate the unidirectional emissions [...] Read more.

Light manipulation at the nanoscale is the vanguard of plasmonics. Controlling light radiation into a desired direction in parallel with high optical signal enhancement is still a challenge for designing ultracompact nanoantennas far below subwavelength dimensions. Here, we theoretically demonstrate the unidirectional emissions from a local nanoemitter coupled to a hybrid nanoantenna consisting of a plasmonic dipole antenna and an individual silicon nanorod. The emitter near-field was coupled to the dipolar antenna plasmon resonance to achieve a strong radiative decay rate modification, and the emitting plasmon pumped the multipoles within the silicon nanorod for efficient emission redirection. The hybrid antenna sustained a high forward directivity (i.e., a front-to-back ratio of 30 dB) with broadband operating wavelengths in the visible range (i.e., a spectral bandwidth of 240 nm). This facilitated a large library of plasmonic nanostructures to be incorporated, from single element dipole antennas to gap antennas. The proposed hybrid optical nanorouter with ultracompact structural dimensions of 0.08 λ² was capable of spectrally sorting the emission from the local point source into distinct far-field directions, as well as possessing large emission gains introduced by the nanogap. The distinct features of antenna designs hold potential in the areas of novel nanoscale light sources, biosensing, and optical routing. Full article

(This article belongs to the Special Issue From Nanomaterials to Intelligent Nanosystems)

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7 pages, 1566 KiB

Open AccessArticle

Effects of Interface Induced Natural Strains on Magnetic Properties of FeRh

by Jeongmin Hong, Tiannan Yang, Alpha T. N’Diaye, Jeffrey Bokor and Long You

Nanomaterials 2019, 9(4), 574; https://doi.org/10.3390/nano9040574 - 09 Apr 2019

Cited by 8 | Viewed by 3147

Abstract

FeRh is a unique alloy which shows temperature dependent phase transition magnetic properties. The lattice parameter (a) of this CsCl-type (B2) structure is 4.1712 Å. It undergoes a first order transition from antiferromagnetic (AFM) to ferromagnetic (FM) order at around 370K [...] Read more.

FeRh is a unique alloy which shows temperature dependent phase transition magnetic properties. The lattice parameter (a) of this CsCl-type (B2) structure is 4.1712 Å. It undergoes a first order transition from antiferromagnetic (AFM) to ferromagnetic (FM) order at around 370K and hysteretic behavior while cooling and heating. This meta-magnetic transition of FeRh is accompanied by an isotropic expansion in the unit cell volume, which indicates strong coupling between magnetic and structural properties of FeRh. Consequently, the magnetic and transport properties, such as magnetoresistance (MR), are changed during the transition. Due to its unique thermo-magnetic behaviors, FeRh is very important for future spintronic devices. The structure could be applicable for MR devices such as memory, sensors, and many other applications. It is critical to understand how to systematically influence phase transition of FeRh from naturally applied strains. Here, we investigate magnetic properties of FeRh in different strain environments induced by the substrates with different lattice parameters. The study was performed using synchrotron radiation, temperature dependent magnetometry, and magnetic scanning probe microscopy in addition to Landau theory calculations. We found that the naturally induced strains could modulate the magnetic phase locally and globally. The presence of the segments from the nucleation of the ferromagnetic domains, with a very thin layer in the antiferromagnetic matrix and the domain growth, were observed gradually. Using the systematic phenomena, it could be used for immediate applications in the future generation of phase change random access memory (PC-RAM) devices. Full article

(This article belongs to the Special Issue From Nanomaterials to Intelligent Nanosystems)

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14 pages, 15014 KiB

Open AccessArticle

Large Scale Synthesis of Nanopyramidal-Like VO₂ Films by an Oxygen-Assisted Etching Growth Method with Significantly Enhanced Field Emission Properties

by Zongtao Zhang, Yifei Feng, Yanfeng Gao, Deliang Chen and Guosheng Shao

Nanomaterials 2019, 9(4), 549; https://doi.org/10.3390/nano9040549 - 04 Apr 2019

Cited by 5 | Viewed by 3891

Abstract

The present investigation reported on a novel oxygen-assisted etching growth method that can directly transform wafer-scale plain VO₂ thin films into pyramidal-like VO₂ nanostructures with highly improved field-emission properties. The oxygen applied during annealing played a key role in the formation [...] Read more.

The present investigation reported on a novel oxygen-assisted etching growth method that can directly transform wafer-scale plain VO₂ thin films into pyramidal-like VO₂ nanostructures with highly improved field-emission properties. The oxygen applied during annealing played a key role in the formation of the special pyramidal-like structures by introducing thin oxygen-rich transition layers on the top surfaces of the VO₂ crystals. An etching related growth and transformation mechanism for the synthesis of nanopyramidal films was proposed. Structural characterizations confirmed the formation of a composite VO₂ structure of monoclinic M1 (P21/c) and Mott insulating M2 (C2/m) phases for the films at room temperature. Moreover, by varying the oxygen concentration, the nanocrystal morphology of the VO₂ films could be tuned, ranging over pyramidal, dot, and/or twin structures. These nanopyramidal VO₂ films showed potential benefits for application such as temperature−regulated field emission devices. For one typical sample deposited on a 3-inch silicon substrate, its emission current (measured at 6 V/μm) increased by about 1000 times after the oxygen-etching treatment, and the field enhancement factor β reached as high as 3810 and 1620 for the M and R states, respectively. The simple method reported in the present study may provide a protocol for building a variety of large interesting surfaces for VO₂-based device applications. Full article

(This article belongs to the Special Issue From Nanomaterials to Intelligent Nanosystems)

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9 pages, 1838 KiB

Open AccessArticle

Facile Fabrication of a Self-Healing Temperature-Sensitive Sensor Based on Ionogels and Its Application in Detection Human Breath

by Fengxia Wang, Shaohui Zhang, Yunlin Zhang, Qihang Lin, Yun Chen, Dongfang Zhu, Lining Sun and Tao Chen

Nanomaterials 2019, 9(3), 343; https://doi.org/10.3390/nano9030343 - 03 Mar 2019

Cited by 15 | Viewed by 3606

Abstract

The biocompatible strechable ionogels were prepared by a facile solution-processed method. The ionogels showed outstanding stretchable and self-healing properties. The electrical property could revert to its original state after 4 s. The repaired ionogels could still bear stretching about 150%. Moreover, the ionogels [...] Read more.

The biocompatible strechable ionogels were prepared by a facile solution-processed method. The ionogels showed outstanding stretchable and self-healing properties. The electrical property could revert to its original state after 4 s. The repaired ionogels could still bear stretching about 150%. Moreover, the ionogels exhibited high sensitivity and wide-detection range to temperature. The temperature-sensitive sensor could detect the human breath frequency and intensity, showing potential application in detecting disease. Full article

(This article belongs to the Special Issue From Nanomaterials to Intelligent Nanosystems)

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13 pages, 3050 KiB

Open AccessArticle

Wavelength-Flattened Directional Coupler Based Mid-Infrared Chemical Sensor Using Bragg Wavelength in Subwavelength Grating Structure

by Bowei Dong, Ting Hu, Xianshu Luo, Yuhua Chang, Xin Guo, Hong Wang, Dim-Lee Kwong, Guo-Qiang Lo and Chengkuo Lee

Nanomaterials 2018, 8(11), 893; https://doi.org/10.3390/nano8110893 - 01 Nov 2018

Cited by 41 | Viewed by 4597

Abstract

In this paper, we report a compact wavelength-flattened directional coupler (WFDC) based chemical sensor featuring an incorporated subwavelength grating (SWG) structure for the mid-infrared (MIR). By incorporating a SWG structure into directional coupler (DC), the dispersion in DC can be engineered to allow [...] Read more.

In this paper, we report a compact wavelength-flattened directional coupler (WFDC) based chemical sensor featuring an incorporated subwavelength grating (SWG) structure for the mid-infrared (MIR). By incorporating a SWG structure into directional coupler (DC), the dispersion in DC can be engineered to allow broadband operation which is advantageous to extract spectroscopic information for MIR sensing analysis. Meanwhile, the Bragg reflection introduced by the SWG structure produces a sharp trough at the Bragg wavelength. This sharp trough is sensitive to the surrounding refractive index (RI) change caused by the existence of analytes. Therefore, high sensitivity can be achieved in a small footprint. Around fivefold enhancement in the operation bandwidth compared to conventional DC is achieved for 100% coupling efficiency in a 40 µm long WFDC experimentally. Detection of dichloromethane (CH₂Cl₂) in ethanol (C₂H₅OH) is investigated in a SWG-based WFDC sensor 136.8 µm long. Sensing performance is studied by 3D finite-difference time domain (FDTD) simulation while sensitivity is derived by computation. Both RI sensing and absorption sensing are examined. RI sensing reveals a sensitivity of −0.47% self-normalized transmitted power change per percentage of CH₂Cl₂ concentration while 0.12% change in the normalized total integrated output power is realized in the absorption sensing. As the first demonstration of the DC based sensor in the MIR, our device has the potential for tertiary mixture sensing by utilizing both changes in the real and imaginary part of RI. It can also be used as a broadband building block for MIR application such as spectroscopic sensing system. Full article

(This article belongs to the Special Issue From Nanomaterials to Intelligent Nanosystems)

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15 pages, 5416 KiB

Open AccessArticle

Investigation of Position Sensing and Energy Harvesting of a Flexible Triboelectric Touch Pad

by Tao Chen, Qiongfeng Shi, Kunpu Li, Zhan Yang, Huicong Liu, Lining Sun, Jan A. Dziuban and Chengkuo Lee

Nanomaterials 2018, 8(8), 613; https://doi.org/10.3390/nano8080613 - 13 Aug 2018

Cited by 29 | Viewed by 5303

Abstract

Triboelectric nanogenerator (TENG) is a promising technology because it can harvest energy from the environment to enable self-sustainable mobile and wearable electronic devices. In this work, we present a flexible touch pad capable of detecting the contact location of an object and generating [...] Read more.

Triboelectric nanogenerator (TENG) is a promising technology because it can harvest energy from the environment to enable self-sustainable mobile and wearable electronic devices. In this work, we present a flexible touch pad capable of detecting the contact location of an object and generating substantial energy simultaneously based on the coupling of triboelectric effects and electrostatic induction. The touch pad consists of Polytetrafluoroethylene (PTFE) thin film, multiple Aluminum (Al) electrodes and Polyethylene terephthalate (PET) layers, which can be achieved through low cost, simplified and scalable fabrication process. Different from the conventional multi-pixel-based positioning sensor (i.e., large array of sensing elements and electrodes), the analogue method proposed here is used to implement the positioning function with only four electrodes. Position location can achieve a detecting resolution of as small as 1.3 mm (the size of locating layer is 7.5 cm × 7.5 cm). For the energy harvesting part, a multilayer structure is designed to provide higher current output. The open circuit voltage of the device is around 420 V and the short circuit current can reach up to 6.26 µA with current density of 0.25 µA/cm². The maximum output power obtained is approximately 10 mW, which is 0.4 mW/cm². The flexibility and significantly reduced number of electrodes enable the proposed touch pad to be readily integrated into portable electronic devices, such as intelligent robots, laptops, healthcare devices, and environmental surveys, etc. Full article

(This article belongs to the Special Issue From Nanomaterials to Intelligent Nanosystems)

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14 pages, 6456 KiB

Open AccessArticle

A Self-Powered Six-Axis Tactile Sensor by Using Triboelectric Mechanism

by Tao Chen, Qiongfeng Shi, Zhan Yang, Jinchang Liu, Huicong Liu, Lining Sun and Chengkuo Lee

Nanomaterials 2018, 8(7), 503; https://doi.org/10.3390/nano8070503 - 06 Jul 2018

Cited by 18 | Viewed by 4326

Abstract

Triboelectric nanogenerators (TENGs) are highly promising because they can scavenge energy from their working environment to sustainably power wearable/mobile electronics. In this work, we propose a novel and straightforward strategy for six-axis force detection and object controlling by using a self-powered sensor based [...] Read more.

Triboelectric nanogenerators (TENGs) are highly promising because they can scavenge energy from their working environment to sustainably power wearable/mobile electronics. In this work, we propose a novel and straightforward strategy for six-axis force detection and object controlling by using a self-powered sensor based on TENG. The self-powered sensor can be used in diversified tactile sensing and energy saving applications, which has been demonstrated to be able to detect normal force in the range of 0–18 N. Using the vector properties of external force, six-axis directions in three-dimensional (3D) space is detected. Additionally, it is fabricated with environmental friendly materials, i.e., galinstan and polydimethylsiloxane (PDMS), promoting its applications in more diversified situations. Because of the available and high output voltage as well as the low internal impedance, the self-powered sensor is readily compatible with commercial signal processing and management circuits. The device presented in this work shows robust structure and stable output performance, enabling itself as an ideal human machine interface in self-powered, batteryless, and electric energy saving applications. Full article

(This article belongs to the Special Issue From Nanomaterials to Intelligent Nanosystems)

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