Editorial

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2 pages, 146 KiB

Open AccessEditorial

Editorial for the Special Issue on Carbon Based Electronic Devices

by

Alberto Tagliaferro

and

Costas Charitidis

Micromachines 2019, 10(12), 856; https://doi.org/10.3390/mi10120856 - 06 Dec 2019

Viewed by 1510

Abstract

For more than 50 years, silicon has dominated the electronics industry [...] Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

Research

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17 pages, 3774 KiB

Open AccessArticle

Graphene Oxide Decorated Nanometal-Poly(Anilino-Dodecylbenzene Sulfonic Acid) for Application in High Performance Supercapacitors

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Konstantinos Kordatos

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Emmanuel I. Iwuoha

Micromachines 2019, 10(2), 115; https://doi.org/10.3390/mi10020115 - 11 Feb 2019

Cited by 22 | Viewed by 3221

Abstract

Graphene oxide (GO) decorated with silver (Ag), copper (Cu) or platinum (Pt) nanoparticles that are anchored on dodecylbenzene sulfonic acid (DBSA)-doped polyaniline (PANI) were prepared by a simple one-step method and applied as novel materials for high performance supercapacitors. High-resolution transmission electron microscopy [...] Read more.

Graphene oxide (GO) decorated with silver (Ag), copper (Cu) or platinum (Pt) nanoparticles that are anchored on dodecylbenzene sulfonic acid (DBSA)-doped polyaniline (PANI) were prepared by a simple one-step method and applied as novel materials for high performance supercapacitors. High-resolution transmission electron microscopy (HRTEM) and high-resolution scanning electron microscopy (HRSEM) analyses revealed that a metal-decorated polymer matrix is embedded within the GO sheet. This caused the M/DBSA–PANI (M = Ag, Cu or Pt) particles to adsorb on the surface of the GO sheets, appearing as aggregated dark regions in the HRSEM images. The Fourier transform infrared (FTIR) spectroscopy studies revealed that GO was successfully produced and decorated with Ag, Cu or Pt nanoparticles anchored on DBSA–PANI. This was confirmed by the appearance of the GO signature epoxy C–O vibration band at 1040 cm⁻¹ (which decreased upon the introduction of metal nanoparticle) and the PANI characteristic N–H stretching vibration band at 3144 cm⁻¹ present only in the GO/M/DBSA–PANI systems. The composites were tested for their suitability as supercapacitor materials; and specific capacitance values of 206.4, 192.8 and 227.2 F·g⁻¹ were determined for GO/Ag/DBSA–PANI, GO/Cu/DBSA–PANI and GO/Pt/DBSA–PANI, respectively. The GO/Pt/DBSA–PANI electrode exhibited the best specific capacitance value of the three electrodes and also had twice the specific capacitance value reported for Graphene/MnO₂//ACN (113.5 F·g⁻¹). This makes GO/Pt/DBSA–PANI a very promising organic supercapacitor material. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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9 pages, 5825 KiB

Open AccessArticle

Nano-Graphitic based Non-Volatile Memories Fabricated by the Dynamic Spray-Gun Deposition Method

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Paolo Bondavalli

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Marie Blandine Martin

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Louiza Hamidouche

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Alberto Montanaro

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Aikaterini-Flora Trompeta

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Costas A. Charitidis

Micromachines 2019, 10(2), 95; https://doi.org/10.3390/mi10020095 - 29 Jan 2019

Cited by 7 | Viewed by 2901

Abstract

This paper deals with the fabrication of Resistive Random Access Memory (ReRAM) based on oxidized carbon nanofibers (CNFs). Stable suspensions of oxidized CNFs have been prepared in water and sprayed on an appropriate substrate, using the dynamic spray-gun deposition method, developed at Thales [...] Read more.

This paper deals with the fabrication of Resistive Random Access Memory (ReRAM) based on oxidized carbon nanofibers (CNFs). Stable suspensions of oxidized CNFs have been prepared in water and sprayed on an appropriate substrate, using the dynamic spray-gun deposition method, developed at Thales Research and Technology. This technique allows extremely uniform mats to be produced while heating the substrate at the boiling point of the solvent used for the suspensions. A thickness of around 150 nm of CNFs sandwiched between two metal layers (the metalized substrate and the top contacts) has been achieved, creating a Metal-Insulator-Metal (MIM) structure typical of ReRAM. After applying a bias, we were able to change the resistance of the oxidized layer between a low (LRS) and a high resistance state (HRS) in a completely reversible way. This is the first time that a scientific group has produced this kind of device using CNFs and these results pave the way for the further implementation of this kind of memory on flexible substrates. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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14 pages, 4234 KiB

Open AccessArticle

Laser Treatments for Improving Electrical Conductivity and Piezoresistive Behavior of Polymer–Carbon Nanofiller Composites

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Micromachines 2019, 10(1), 63; https://doi.org/10.3390/mi10010063 - 18 Jan 2019

Cited by 14 | Viewed by 3681

Abstract

The effect of carbon nanotubes, graphene-like platelets, and another carbonaceous fillers of natural origin on the electrical conductivity of polymeric materials was studied. With the aim of keeping the filler content and the material cost as low as possible, the effect of laser [...] Read more.

The effect of carbon nanotubes, graphene-like platelets, and another carbonaceous fillers of natural origin on the electrical conductivity of polymeric materials was studied. With the aim of keeping the filler content and the material cost as low as possible, the effect of laser surface treatments on the conductivity of polymer composites with filler load below the percolation threshold was also investigated. These treatments allowed processing in situ conductive tracks on the surface of insulating polymer-based materials. The importance of the kinds of fillers and matrices, and of the laser process parameters was studied. Carbon nanotubes were also used to obtain piezoresistive composites. The electrical response of these materials to a mechanical load was investigated in view of their exploitation for the production of pressure sensors and switches based on the piezoresistive effect. It was found that the piezoresistive behavior of composites with very low filler concentration can be improved with proper laser treatments. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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10 pages, 2394 KiB

Open AccessArticle

Pressure Sensitivity Enhancement of Porous Carbon Electrode and Its Application in Self-Powered Mechanical Sensors

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Micromachines 2019, 10(1), 58; https://doi.org/10.3390/mi10010058 - 16 Jan 2019

Cited by 5 | Viewed by 3371

Abstract

Microsystems with limited power supplies, such as electronic skin and smart fuzes, have a strong demand for self-powered pressure and impact sensors. In recent years, new self-powered mechanical sensors based on the piezoresistive characteristics of porous electrodes have been rapidly developed, and have [...] Read more.

Microsystems with limited power supplies, such as electronic skin and smart fuzes, have a strong demand for self-powered pressure and impact sensors. In recent years, new self-powered mechanical sensors based on the piezoresistive characteristics of porous electrodes have been rapidly developed, and have unique advantages compared to conventional piezoelectric sensors. In this paper, in order to optimize the mechanical sensitivity of porous electrodes, a material preparation process that can enhance the piezoresistive characteristics is proposed. A flexible porous electrode with superior piezoresistive characteristics and elasticity was prepared by modifying the microstructure of the porous electrode material and adding an elastic rubber component. Furthermore, based on the porous electrode, a self-powered pressure sensor and an impact sensor were fabricated. Through experimental results, the response signals of the sensors present a voltage peak under such mechanical effects and the sensitive signal has less clutter, making it easy to identify the features of the mechanical effects. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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9 pages, 2863 KiB

Open AccessArticle

Spray-On Liquid-Metal Electrodes for Graphene Field-Effect Transistors

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Micromachines 2019, 10(1), 54; https://doi.org/10.3390/mi10010054 - 14 Jan 2019

Cited by 13 | Viewed by 4412

Abstract

Advancements in flexible circuit interconnects are critical for widespread adoption of flexible electronics. Non-toxic liquid-metals offer a viable solution for flexible electrodes due to deformability and low bulk resistivity. However, fabrication processes utilizing liquid-metals suffer from high complexity, low throughput, and significant production [...] Read more.

Advancements in flexible circuit interconnects are critical for widespread adoption of flexible electronics. Non-toxic liquid-metals offer a viable solution for flexible electrodes due to deformability and low bulk resistivity. However, fabrication processes utilizing liquid-metals suffer from high complexity, low throughput, and significant production cost. Our team utilized an inexpensive spray-on stencil technique to deposit liquid-metal Galinstan electrodes in top-gated graphene field-effect transistors (GFETs). The electrode stencils were patterned using an automated vinyl cutter and positioned directly onto chemical vapor deposition (CVD) graphene transferred to polyethylene terephthalate (PET) substrates. Our spray-on method exhibited a throughput of 28 transistors in under five minutes on the same graphene sample, with a 96% yield for all devices down to a channel length of 50 μm. The fabricated transistors possess hole and electron mobilities of 663.5 cm²/(V·s) and 689.9 cm²/(V·s), respectively, and support a simple and effective method of developing high-yield flexible electronics. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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13 pages, 8410 KiB

Open AccessArticle

Plasma Surface Functionalization of Carbon Nanofibres with Silver, Palladium and Platinum Nanoparticles for Cost-Effective and High-Performance Supercapacitors

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Micromachines 2019, 10(1), 2; https://doi.org/10.3390/mi10010002 - 21 Dec 2018

Cited by 14 | Viewed by 3108

Abstract

Due to their relatively low cost, large surface area and good chemical and physical properties, carbon nanofibers (CNFs) are attractive for the fabrication of electrodes for supercapacitors (SCs). However, their relatively low electrical conductivity has impeded their practical application. To this end, a [...] Read more.

Due to their relatively low cost, large surface area and good chemical and physical properties, carbon nanofibers (CNFs) are attractive for the fabrication of electrodes for supercapacitors (SCs). However, their relatively low electrical conductivity has impeded their practical application. To this end, a novel active-screen plasma activation and deposition technology has been developed to deposit silver, platinum and palladium nanoparticles on activated CNFs surfaces to increase their specific surface area and electrical conductivity, thus improving the specific capacitance. The functionalised CNFs were fully characterised using scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) and their electrochemical properties were evaluated using cyclic voltammetry and electrochemical impedance spectroscopy. The results showed a significant improvement in specific capacitance, as well as electrochemical impedance over the untreated CNFs. The functionalisation of CNFs via environmental-friendly active-screen plasma technology provides a promising future for cost-effective supercapacitors with high power and energy density. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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9 pages, 2901 KiB

Open AccessArticle

White-Light Photosensors Based on Ag Nanoparticle-Reduced Graphene Oxide Hybrid Materials

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Micromachines 2018, 9(12), 655; https://doi.org/10.3390/mi9120655 - 11 Dec 2018

Cited by 12 | Viewed by 2969

Abstract

The unique and outstanding electrical and optical properties of graphene make it a potential material to be used in the construction of high-performance photosensors. However, the fabrication process of a graphene photosensor is usually complicated and the size of the device also is [...] Read more.

The unique and outstanding electrical and optical properties of graphene make it a potential material to be used in the construction of high-performance photosensors. However, the fabrication process of a graphene photosensor is usually complicated and the size of the device also is restricted to micrometer scale. In this work, we report large-area photosensors based on reduced graphene oxide (rGO) implemented with Ag nanoparticles (AgNPs) via a simple and cost-effective method. To further optimize the performance of photosensors, the absorbance and distribution of the electrical field intensity of graphene with AgNPs was simulated using the finite-difference time-domain (FDTD) method through use of the surface plasmon resonance effect. Based on the simulated results, we constructed photosensors using rGO with 60–80 nm AgNPs and analyzed the characteristics at room temperature under white-light illumination for outdoor environment applications. The on/off ratio of the photosensor with AgNPs was improved from 1.166 to 9.699 at the bias voltage of −1.5 V, which was compared as a sample without AgNPs. The proposed photosensor affords a new strategy to construct cost-effective and large-area graphene films which raises opportunities in the field of next-generation optoelectronic devices operated in an outdoor environment. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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9 pages, 4376 KiB

Open AccessArticle

Fabrication of Stable Carbon Nanotube Cold Cathode Electron Emitters with Post-Growth Electrical Aging

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Jung Hyun Kim

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Jung Su Kang

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Kyu Chang Park

Micromachines 2018, 9(12), 648; https://doi.org/10.3390/mi9120648 - 07 Dec 2018

Cited by 9 | Viewed by 3444

Abstract

We fabricated carbon nanotube (CNT) cold cathode emitters with enhanced and stable electron emission properties and long-time stability with electrical aging as a post-treatment. Our CNT field emitters showed improved electrical properties by electrical aging. We set the applied bias for effective electrical [...] Read more.

We fabricated carbon nanotube (CNT) cold cathode emitters with enhanced and stable electron emission properties and long-time stability with electrical aging as a post-treatment. Our CNT field emitters showed improved electrical properties by electrical aging. We set the applied bias for effective electrical aging, with the bias voltage defined at the voltage where Joule heating appeared. At the initial stage of aging, the electron emission current started to increase and then was saturated within 3 h. We understood that 5 h aging time was enough at proper aging bias. If the aging bias is higher, excessive heating damages CNT emitters. With the electrical aging, we obtained improved electron emission current from 3 mA to 6 mA. The current of 6 mA was steadily driven for 9 h. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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7 pages, 3238 KiB

Open AccessArticle

Selective Detection of NO and NO₂ with CNTs-Based Ionization Sensor Array

by

Hui Song

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Kun Li

and

Chang Wang

Micromachines 2018, 9(7), 354; https://doi.org/10.3390/mi9070354 - 16 Jul 2018

Cited by 14 | Viewed by 2927

Abstract

The accurate detection of NO_x is an important issue, because nitrogen oxides are not only environmental pollutants, but also harm to human health. An array composed of two carbon nanotubes (CNTs)-based ionization sensors with different separations is proposed for NO and NO [...] Read more.

The accurate detection of NO_x is an important issue, because nitrogen oxides are not only environmental pollutants, but also harm to human health. An array composed of two carbon nanotubes (CNTs)-based ionization sensors with different separations is proposed for NO and NO₂ selective detection. The experimental results indicate that the CNTs-based ionization sensor has an intrinsic, monotonically decreasing response to NO or NO₂. The sensor with 80 µm separations and 100 µm separations exhibited the highest sensitivity of −0.11 nA/ppm to 300 ppm NO and −0.49 nA /ppm to 70 ppm NO₂, respectively. Although the effect of the NO₂ concentration on the NO response is much stronger than that of NO on NO₂, the array of these two sensors still exhibits the ability to simultaneously detect the concentrations of NO and NO₂ in a gas mixture without component separation. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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Review

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43 pages, 4895 KiB

Open AccessReview

Selective Carbon Material Engineering for Improved MEMS and NEMS

by

Stephane Neuville

Micromachines 2019, 10(8), 539; https://doi.org/10.3390/mi10080539 - 16 Aug 2019

Cited by 36 | Viewed by 4832

Abstract

The development of micro and nano electromechanical systems and achievement of higher performances with increased quality and life time is confronted to searching and mastering of material with superior properties and quality. Those can affect many aspects of the MEMS, NEMS and MOMS [...] Read more.

The development of micro and nano electromechanical systems and achievement of higher performances with increased quality and life time is confronted to searching and mastering of material with superior properties and quality. Those can affect many aspects of the MEMS, NEMS and MOMS design including geometric tolerances and reproducibility of many specific solid-state structures and properties. Among those: Mechanical, adhesion, thermal and chemical stability, electrical and heat conductance, optical, optoelectronic and semiconducting properties, porosity, bulk and surface properties. They can be affected by different kinds of phase transformations and degrading, which greatly depends on the conditions of use and the way the materials have been selected, elaborated, modified and assembled. Distribution of these properties cover several orders of magnitude and depend on the design, actually achieved structure, type and number of defects. It is then essential to be well aware about all these, and to distinguish and characterize all features that are able to affect the results. For this achievement, we point out and discuss the necessity to take into account several recently revisited fundamentals on carbon atomic rearrangement and revised carbon Raman spectroscopy characterizing in addition to several other aspects we will briefly describe. Correctly selected and implemented, these carbon materials can then open new routes for many new and more performing microsystems including improved energy generation, storage and conversion, 2D superconductivity, light switches, light pipes and quantum devices and with new improved sensor and mechanical functions and biomedical applications. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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25 pages, 3542 KiB

Open AccessFeature PaperReview

Functionalized Carbon Materials for Electronic Devices: A Review

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Micromachines 2019, 10(4), 234; https://doi.org/10.3390/mi10040234 - 03 Apr 2019

Cited by 78 | Viewed by 6583

Abstract

Carbon-based materials, including graphene, single walled carbon nanotubes (SWCNTs), and multi walled carbon nanotubes (MWCNTs), are very promising materials for developing future-generation electronic devices. Their efficient physical, chemical, and electrical properties, such as high conductivity, efficient thermal and electrochemical stability, and high specific [...] Read more.

Carbon-based materials, including graphene, single walled carbon nanotubes (SWCNTs), and multi walled carbon nanotubes (MWCNTs), are very promising materials for developing future-generation electronic devices. Their efficient physical, chemical, and electrical properties, such as high conductivity, efficient thermal and electrochemical stability, and high specific surface area, enable them to fulfill the requirements of modern electronic industries. In this review article, we discuss the synthetic methods of different functionalized carbon materials based on graphene oxide (GO), SWCNTs, MWCNTs, carbon fibers (CFs), and activated carbon (AC). Furthermore, we highlight the recent developments and applications of functionalized carbon materials in energy storage devices (supercapacitors), inkjet printing appliances, self-powered automatic sensing devices (biosensors, gas sensors, pressure sensors), and stretchable/flexible wearable electronic devices. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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29 pages, 5738 KiB

Open AccessReview

Carbon-Based Materials for Humidity Sensing: A Short Review

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Jean-Marc Tulliani

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Barbara Inserra

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Daniele Ziegler

Micromachines 2019, 10(4), 232; https://doi.org/10.3390/mi10040232 - 31 Mar 2019

Cited by 91 | Viewed by 5487

Abstract

Humidity sensors are widespread in many industrial applications, ranging from environmental and meteorological monitoring, soil water content determination in agriculture, air conditioning systems, food quality monitoring, and medical equipment to many other fields. Thus, an accurate and reliable measurement of water content in [...] Read more.

Humidity sensors are widespread in many industrial applications, ranging from environmental and meteorological monitoring, soil water content determination in agriculture, air conditioning systems, food quality monitoring, and medical equipment to many other fields. Thus, an accurate and reliable measurement of water content in different environments and materials is of paramount importance. Due to their rich surface chemistry and structure designability, carbon materials have become interesting in humidity sensing. In addition, they can be easily miniaturized and applied in flexible electronics. Therefore, this short review aims at providing a survey of recent research dealing with carbonaceous materials used as capacitive and resistive humidity sensors. This work collects some successful examples of devices based on carbon nanotubes, graphene, carbon black, carbon fibers, carbon soot, and more recently, biochar produced from agricultural wastes. The pros and cons of the different sensors are also discussed in the present review. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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24 pages, 1742 KiB

Open AccessReview

Rheological Issues in Carbon-Based Inks for Additive Manufacturing

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Micromachines 2019, 10(2), 99; https://doi.org/10.3390/mi10020099 - 29 Jan 2019

Cited by 32 | Viewed by 5616

Abstract

As the industry and commercial market move towards the optimization of printing and additive manufacturing, it becomes important to understand how to obtain the most from the materials while maintaining the ability to print complex geometries effectively. Combining such a manufacturing method with [...] Read more.

As the industry and commercial market move towards the optimization of printing and additive manufacturing, it becomes important to understand how to obtain the most from the materials while maintaining the ability to print complex geometries effectively. Combining such a manufacturing method with advanced carbon materials, such as Graphene, Carbon Nanotubes, and Carbon fibers, with their mechanical and conductive properties, delivers a cutting-edge combination of low-cost conductive products. Through the process of printing the effectiveness of these properties decreases. Thorough optimization is required to determine the idealized ink functional and flow properties to ensure maximum printability and functionalities offered by carbon nanoforms. The optimization of these properties then is limited by the printability. By determining the physical properties of printability and flow properties of the inks, calculated compromises can be made for the ink design. In this review we have discussed the connection between the rheology of carbon-based inks and the methodologies for maintaining the maximum pristine carbon material properties. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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27 pages, 7357 KiB

Open AccessReview

Transparent Conductive Electrodes Based on Graphene-Related Materials

by

Yun Sung Woo

Micromachines 2019, 10(1), 13; https://doi.org/10.3390/mi10010013 - 26 Dec 2018

Cited by 51 | Viewed by 6740

Abstract

Transparent conducting electrodes (TCEs) are the most important key component in photovoltaic and display technology. In particular, graphene has been considered as a viable substitute for indium tin oxide (ITO) due to its optical transparency, excellent electrical conductivity, and chemical stability. The outstanding [...] Read more.

Transparent conducting electrodes (TCEs) are the most important key component in photovoltaic and display technology. In particular, graphene has been considered as a viable substitute for indium tin oxide (ITO) due to its optical transparency, excellent electrical conductivity, and chemical stability. The outstanding mechanical strength of graphene also provides an opportunity to apply it as a flexible electrode in wearable electronic devices. At the early stage of the development, TCE films that were produced only with graphene or graphene oxide (GO) were mainly reported. However, since then, the hybrid structure of graphene or GO mixed with other TCE materials has been investigated to further improve TCE performance by complementing the shortcomings of each material. This review provides a summary of the fabrication technology and the performance of various TCE films prepared with graphene-related materials, including graphene that is grown by chemical vapor deposition (CVD) and GO or reduced GO (rGO) dispersed solution and their composite with other TCE materials, such as carbon nanotubes, metal nanowires, and other conductive organic/inorganic material. Finally, several representative applications of the graphene-based TCE films are introduced, including solar cells, organic light-emitting diodes (OLEDs), and electrochromic devices. Full article

(This article belongs to the Special Issue Carbon Based Electronic Devices)

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