Name: development and functionalization of electrolyte-gated graphene field-effect transistor for biomarker detection
Uploaded: 2022-02-01T14:20:00
Description: Watch this Scientific Journal Video about Development and Functionalization of Electrolyte-Gated Graphene Field-Effect Transistor for Biomarker Detection at JoVE.com

The experiments were conducted at West Virginia University. We acknowledge the Shared Research Facilities at West Virginia University for device fabrication and material characterization. This work was supported by the US National Science Foundation under Grant No. NSF1916894.

1. Transferring chemical vapor deposition of graphene
<ol>
	<li>Cut the graphene sheet on a copper substrate in half (2.5 cm x 5 cm) using scissors. Apply heat resistive tape to fix the four corners of the graphene square on a spinner gasket (see Table of Materials). 
	NOTE: The purchased graphene has a dimension of 5 cm x 5 cm (see Table of Materials).</li>
	<li>Spin-coat the sheet of the graphene with a thin layer (100-200 nm) of PMMA 495K A4 spinning at 500 rpm...

<ol>
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C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intrinsic+response+of+graphene+vapor+sensors.">Intrinsic response of graphene vapor sensors.</a> Nano Letters. 9 (4), 1472-1475 (2009).</li><li>Zhang, A., Lieber, C. M. -. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nano-Bioelectronics.">Nano-Bioelectronics.</a> Chemical Reviews. 116 (1), 215-257 (2015).</li><li>Forsyth, R., Devadoss, A., Guy, O. 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The purchased CVD graphene on copper film needs to be trimmed to the right size for the following fabrication steps. Cutting of the films can cause wrinkling, which needs to be prevented. The parameters provided in the fabrication step can be referred to for plasma etching of graphene, and these numbers could be varied when using different instruments. The etched sample must be closely monitored and inspected to ensure complete graphene etching. Multiple pre-cleaning methods can be applied to clean the substrates, such a...

Graphene and its derivatives have been investigated and used for many applications, including electronics1,2, sensing3,4,5, energy storage6,7, and photocatalysis1,6,8. Synthesis and fabrication of high quality, good uniformity, and low defects graphene are critical for high-performance and highly sensitive devices. Since the development of Chemical vapor deposition (CVD) in 2009, it has shown colossal promise and set its place as an essential member of the graphene family9,10,11,12,13. It is grown on a metal substrate and, later for practical uses, is transferred onto insulating substrates14. Several transferring methods have been used to transfer CVD graphene recently. The poly (methyl methacrylate) (PMMA) assisted method is the most used among the different techniques. This method is particularly well-suited for industrial usage because of its large-scale capability, lower cost, and high quality of the transferred graphene14,15. The critical aspect of this method is getting rid of the PMMA residue for CVD graphene&#39;s applications because the residues can cause declination of the electronic properties of graphene14,15,16, cause an effect on biosensors&#39; sensitivity and performance17,18, and create significant device-to-device variations19.
Nanomaterials-based biosensors have been significantly investigated over the past decades, including silicon nanowire (SiNW), carbon nanotube (CNT), and graphene20. Because of its single-atom-layer structure and distinctive properties, graphene demonstrates superior electronic characteristics, good biocompatibility, and facile functionalization, making it an attractive material for developing biosensors14,21,22,23. Due to field-effect transistors (FET) characteristics such as high sensitivity, standard configuration, and cost-effective mass producibility21,24, FET is more preferred in portable and point-of-care implementations than other electronics-based biosensing devices. The electrolyte-gated graphene field-effect transistor (EGGFET) biosensors are examples of the stated FETs21,24. EGGFET can detect various targeting analytes such as nucleic acids25, proteins24,26, metabolites27, and other biologically relevant analytes28. The technique mentioned here ensures the implementation of CVD graphene in a label-free biosensing nanoelectronics device which offers higher sensitivity and accurate time detection over other biosensing devices29.
In this work, an overall process for developing an EGGFET biosensor and functionalizing it for biomarker detection, including transferring CVD graphene onto an insulating substrate, Raman, and AFM characterizations of the transferred graphene, are demonstrated. Furthermore, fabrication of EGGFET and integration with a polydimethylsiloxane (PDMS) sample delivery well, bioreceptor functionalization, and successful detection of human immunoglobulin G (IgG) from serum by spike-and-recovery experiments are also discussed here.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1-pyreneutyric acid N- hydroxysuccinimide ester</td>
			<td>Sigma Aldrich</td>
			<td>457078-1G</td>
			<td>functionalization</td>
		</tr>
		<tr>
			<td>Asylum MFP-3D Atomic Force Microscope</td>
			<td>Oxford Instruments</td>
			<td></td>
			<td>graphene characterization</td>
		</tr>
		<tr>
			<td>AZ 300 MIF</td>
			<td>MicroChemicals</td>
			<td>AZ 300 MIF</td>
			<td>photoresist developer</td>
		</tr>
		<tr>
			<td>AZ 300 MIF</td>
			<td>MicroChemicals</td>
			<td>AZ 300 MIF</td>
			<td>photoresist</td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Sigma Aldrich</td>
			<td>810014</td>
			<td>blocking</td>
		</tr>
		<tr>
			<td>Branson 1210 Sonicator</td>
			<td>SONITEK</td>
			<td></td>
			<td>sample cleaning</td>
		</tr>
		<tr>
			<td>Copper Etchant</td>
			<td>Sigma Aldrich</td>
			<td>667528-500ML</td>
			<td>removing copper film to release graphene</td>
		</tr>
		<tr>
			<td>Dimethyl Sulfoxide (DMSO)</td>
			<td>VWR</td>
			<td>97063-136</td>
			<td>functionalization</td>
		</tr>
		<tr>
			<td>Disposable Biopsy Punches, Integra Miltex</td>
			<td>VWR</td>
			<td>21909-144</td>
			<td>create well in PDMS</td>
		</tr>
		<tr>
			<td>Gold etchant</td>
			<td>Gold Etch, TFA, Transene</td>
			<td>658148</td>
			<td>enchant</td>
		</tr>
		<tr>
			<td>Graphene</td>
			<td>Graphene supermarket</td>
			<td>2&#34; x 2&#34; sheet</td>
			<td>biosensing element of the device</td>
		</tr>
		<tr>
			<td>IgG aptamer</td>
			<td>Base Pair Biotechnologies</td>
			<td>customized</td>
			<td>bioreceptor</td>
		</tr>
		<tr>
			<td>Keithley 4200A-SCS Parameter Analyzer</td>
			<td>Tektronix</td>
			<td></td>
			<td>measurement and detection</td>
		</tr>
		<tr>
			<td>KMG CR-6</td>
			<td>KMG chemicals</td>
			<td>64216</td>
			<td>Chromium etchant</td>
		</tr>
		<tr>
			<td>Kurt J. Lesker E-beam Evaporator</td>
			<td>Kurt J. Lesker</td>
			<td></td>
			<td>metal deposition</td>
		</tr>
		<tr>
			<td>Laurell Technologies 400 Spinners</td>
			<td>Laurell Technologies</td>
			<td>WS-400BZ-6NPP/LITE</td>
			<td>thin film coating</td>
		</tr>
		<tr>
			<td>March PX-250 Plasma Asher</td>
			<td>March Instruments</td>
			<td></td>
			<td>sample cleaning</td>
		</tr>
		<tr>
			<td>Nickel etchant</td>
			<td>Nickel Etchant, TFB, Transene</td>
			<td>600016000</td>
			<td>etchant</td>
		</tr>
		<tr>
			<td>OAI Flood Exposure</td>
			<td>OAI</td>
			<td></td>
			<td>photolithography</td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS)</td>
			<td>Sigma Aldrich</td>
			<td>806552-500ML</td>
			<td>buffer</td>
		</tr>
		<tr>
			<td>PMMA 495K A4</td>
			<td>MicroChemicals</td>
			<td>PMMA 495K A4</td>
			<td>Photoresist for assisting graphene transferring</td>
		</tr>
		<tr>
			<td>Polydimethylsiloxane (PDMS)</td>
			<td>Sigma Aldrich</td>
			<td>Sylgard 184</td>
			<td>sample delivery well</td>
		</tr>
		<tr>
			<td>Renishaw InVia Raman Microscope</td>
			<td>Renishaw</td>
			<td></td>
			<td>graphene characterization</td>
		</tr>
		<tr>
			<td>Sodium Hydroxide (NaOH)</td>
			<td>Sigma Aldrich</td>
			<td>221465-25G</td>
			<td>functionalization</td>
		</tr>
		<tr>
			<td>Suss Microtech MA6 Mask Aligner</td>
			<td>Suss MicroTec</td>
			<td></td>
			<td>photolithography</td>
		</tr>
		<tr>
			<td>Thermo Scientific Cimarec Hotplate</td>
			<td>Thermo Scientific</td>
			<td>SP131635</td>
			<td>sample and device Baking</td>
		</tr>
	</tbody>
</table>

development and functionalization of electrolyte-gated graphene field-effect transistor for biomarker detection

In the current study, graphene and its derivatives have been investigated and used for many applications, including electronics, sensing, energy storage, and photocatalysis. Synthesis and fabrication of high quality, good uniformity, and low defects graphene are critical for high-performance and highly sensitive devices. Among many synthesis methods, chemical vapor deposition (CVD), considered a leading approach to manufacture graphene, can control the number of graphene layers and yield high-quality graphene. CVD graphene needs to be transferred from the metal substrates on which it is grown onto&#160;insulating substrates for practical applications. However, separation and transferring of graphene onto new substrates are challenging for a uniform layer without damaging or affecting graphene&#39;s structures and properties. Additionally, electrolyte-gated graphene field-effect transistor (EGGFET) has been demonstrated for its wide applications in various biomolecular detections because of its high sensitivity and standard device configuration. In this article, poly (methyl methacrylate) (PMMA)-assisted graphene transferring approach, fabrication of graphene field-effect transistor (GFET), and biomarker immunoglobulin G (IgG) detection are demonstrated. Raman spectroscopy and atomic force microscopy were applied to characterize the transferred graphene. The method is shown to be a practical approach for transferring clean and residue-free graphene while preserving the underlying graphene lattice onto an insulating substrate for electronics or biosensing applications.

The representative results show the transferred CVD graphene characterized by Raman and AFM, respectively. The G peak and the 2D peaks of the Raman image give comprehensive information regarding the existence and the quality of the transferred monolayer graphene32 (Figure 1). Standard lithography processes30,31 were applied for fabricating the GFET device, as shown in Figure 2. <s...

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Development and Functionalization of Electrolyte-Gated Graphene Field-Effect Transistor for Biomarker Detection

The present protocol demonstrates the development of electrolyte-gated graphene field-effect transistor (EGGFET) biosensor and its application in biomarker immunoglobulin G (IgG) detection.

In the current study, graphene and its derivatives have been investigated and used for many applications, including electronics, sensing, energy storage, ...

The method effectively removes PMMA residue while preserving the underlying graphene lattice. The functional device shows consistent results in detecting IgG antibodies in blood serum. Also, the protocol ensures the implementation of CVD graphene in a realtime, label-free biosensing device.The steps are pretty simple and can be done with minimal training. The device offers high selectivity, high sensitivity, and realtime detection over other biosensing devices Begin by cutting the graphene sheet on a copper substrate in half using a scalpel. Apply heat-resistant tape to fix the four corners of the graphene square on a spinner gasket.Spin coat the square sheet of the graphene with a thin layer of 100 to 200 nanometers of PMMA 495K A4, spinning at 500 rotations per minute for 10 seconds, and then 2, 000 rotations per minute for 50 seconds. Then, bake the sample at 150 degrees Celsius for five minutes. Remove the backside of the graphene with oxygen plasma at 30 watt using a rate flow of 15 standard cubic centimeters per minute for five minutes.Cut the plasma-treated graphene square into a dimension of one-centimeter width and two-centimeter height for device fabrication. Cut the pre-cleaned silica substrate into small pieces with an approximate four-centimeter width and two-centimeter height. Etch the copper off using the graphene etchant ferric chloride without dilution.Float the sample with the copper side down and the PMMA side up on the liquid etchant. After copper etching, lift the graphene film slowly using the plasma-treated substrate. Air dry the transferred graphene film for two hours, then bake on a hot plate.To remove PMMA, start by warming up the sample with acetone vapor at 70 degrees Celsius by keeping the sample approximately two centimeters above acetone vapor for four minutes with the PMMA side facing down. Then, immerse the sample in acetone for five minutes. Wash the sample with deionized water cautiously.Finally, gently blow dry the sample with nitrogen. Wash the substrate with the transferred graphene using acetone, isopropyl alcohol, and deionized water. Then, bake the substrate on a hot plate at 75 degrees Celsius for 30 minutes.Using an electron beam evaporator, deposit nickel and gold of 5 and 45 nanometers thickness, respectively, on the graphene sample. Apply the first photolithography process using mask A for the patterning of the electrodes. Spin AZ 5214E positive photoresist on the sample at 2, 000 rotations per minute for 45 seconds and cure the sample at 120 degrees Celsius for one minute.Place the sample in the ultraviolet flood exposure system and expose it for approximately 10 seconds under 200 millijoules per square centimeter. Develop the sample with a photoresist developer AZ 300 MIF for approximately two minutes and then rinse with deionized water. Immerse the sample in a gold etchant to etch the gold layer for 10 seconds, rinse with deionized water, and remove the remaining photoresist layer by immersing in acetone for 10 minutes.Using acetone, isopropyl alcohol, and deionized water, wash the sample followed by baking on a hot plate at 75 degrees Celsius for 30 minutes. Then, apply the second photolithography process using mask B to pattern the graphene channels. Immerse the sample in nickel etchant at 60 degrees Celsius to etch the nickel layer for 10 seconds.Rinse with deionized water and blow dry using nitrogen. Place the sample in the plasma asher and remove the exposed graphene using oxygen plasma. Later, remove the photoresist layer by immersing in acetone for 10 minutes.Wash the sample using acetone, IPA, and deionized water and bake on a hot plate at 75 degrees Celsius for 30 minutes. Apply the third photolithography process using mask C to pattern the passivation photoresist layer to protect the underlying graphene on the substrate. Use the same process parameters as previously mentioned, including spinning with positive photoresist, curing the sample, and developing with photoresist developer.Later, immerse the sample in nickel etchant at 60 degrees Celsius for 10 seconds to remove the remaining nickel layer, and then rinse with deionized water and blow dry using nitrogen. Finally, bake the sample on a hot plate at 120 degrees Celsius for 30 minutes. The representative results show the transferred CVD graphene characterized by Raman and atomic force microscopy.The G peak and the two-dimensional peaks of the Raman image give comprehensive information regarding the existence and the quality of the transferred monolayer graphene. The figure shows EEG FET biosensor integrated with a standard silver in silver chloride reference electrode and a polydimethyl siloxane well for containing the sample. Further, the enlarged view of the graphene channel demonstrates the connection to the source electrode to the ground, the drain, and the gate electrodes to the source.PBASE, a widely used functionalization reagent for graphene, can be absorbed on graphene surface through a pi-pi interaction without damaging graphene's electrical properties. A 5-prime amino-modified IgG aptamer is conjugated with PBASE by the amide bond linkages between the reactive and hydroxy-6 cinnamide ester in PBASE, and the amine group on the 5-prime end of the IgG aptamer. Bovine serum albumin incubation was used to block the remaining unconjugated sites after rinsing the device with single-strength PBS The figure shows the IgG detection under different electrolyte conditions.The quality of the graphene is the key to the best performance of this device. So during plasma etching, it needs to be ensured that the plasma does not harm the useful regions of the graphene. Also, the PMMA residues need to be cleaned altogether to get a clean graphene surface.The functional device shows consistent results in detecting human IgG antibody, so the procedure can be used as a reference to build devices with other nanomaterials to study interface interactions and biosensing.

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Synthesis and Functionalization of Nitrogen-doped Carbon Nanotube Cups with Gold Nanoparticles as Cork Stoppers

Nitrogen-doped carbon nanotubes consist of many cup-shaped graphitic compartments termed as nitrogen-doped carbon nanotube cups (NCNCs). These as-synthesized graphitic nanocups from chemical vapor deposition (CVD) method were stacked in a head-to-tail fashion held only through noncovalent interactions. Individual NCNCs can be isolated out of their stacking structure through a series of chemical and physical separation processes. First, as-synthesized NCNCs were oxidized in a mixture of strong acids to introduce oxygen-containing defects on the graphitic walls. The oxidized NCNCs were then processed using high-intensity probe-tip sonication which effectively separated the stacked NCNCs into individual graphitic nanocups. Owing to their abundant oxygen and nitrogen surface functionalities, the resulted individual NCNCs are highly hydrophilic and can be effectively functionalized with gold nanoparticles (GNPs), which preferentially fit in the opening of the cups as cork stoppers. These graphitic nanocups corked with GNPs may find promising applications as nanoscale containers and drug carriers.

We discussed the synthesis of individual graphitic nanocups using a series of techniques including chemical vapor deposition, acid oxidation and probe-tip sonication. By citrate reduction of HAuCl4, the graphitic nanocups were effectively corked with gold nanoparticles due to the chemically reactive edges of the cups.

Nitrogen-doped carbon  nanotubes consist of many cup-shaped graphitic compartments termed as  nitrogen-doped carbon nanotube cups (NCNCs).  These ...

Development of a 3D Graphene Electrode Dielectrophoretic Device

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The protocol details the procedures to construct a versatile, reusable, multiple layer, laminated dielectrophoresis chamber. Specifically, six layers of 50 &#181;m x&#160;0.7 cm x&#160;2 cm graphene paper and five layers of double sided tape were alternately stacked together, then clamped to a glass slide. Then a 700 &#956;m diameter micro-well was drilled through the laminated structure using a computer-controlled micro drilling machine. Insulating properties of the tape layer between adjacent graphene layers were assured by resistance tests. Silver conductive epoxy connected alternate layers of graphene paper and formed stable connections between the graphene paper and external copper wire electrodes. The finished device was then clamped and sealed to a glass slide. The electric field gradient was modeled within the multi-layer device. Dielectrophoretic behaviors of 6 &#956;m polystyrene beads were demonstrated in the 1 mm deep micro-well, with medium conductivities ranging from 0.0001 S/m to 1.3 S/m, and applied signal frequencies from 100 Hz to 10 MHz. Negative dielectrophoretic responses were observed in three dimensions over most of the conductivity-frequency space and cross-over frequency values are consistent with previously reported literature values. The device did not prevent AC electroosmosis and electrothermal flows, which occurred in the low and high frequency regions, respectively. The graphene paper utilized in this device is versatile and could subsequently function as a biosensor after dielectrophoretic characterizations are complete.

A microdevice with high throughput potential is used to demonstrate three-dimensional (3D) dielectrophoresis (DEP) with novel materials. Graphene nanoplatelet paper and double sided tape were alternately stacked; a 700 &#956;m micro-well was drilled transverse to the layers. DEP behavior of polystyrene beads was demonstrated in the micro-well.

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The ...

Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities

Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees of freedom to control electronic devices. In particular, the behavior of graphene&#8217;s charge carriers in response to potentials from charged Coulomb impurities is predicted to differ significantly from that of most materials. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) can provide detailed information on both the spatial and energy dependence of graphene&#39;s electronic structure in the presence of a charged impurity.&#160;The design of a hybrid impurity-graphene device, fabricated using controlled deposition of impurities onto a back-gated graphene surface, has enabled several novel methods for controllably tuning graphene&#8217;s electronic properties.1-8 Electrostatic gating enables control of the charge carrier density in graphene and the ability to reversibly tune the charge2 and/or molecular5 states of an impurity. This paper outlines the process of fabricating a gate-tunable graphene device decorated with individual Coulomb impurities for combined STM/STS studies.2-5 These studies provide valuable insights into the underlying physics, as well as signposts for designing hybrid graphene devices.

This paper details the fabrication process of a gate-tunable graphene device, decorated with Coulomb impurities for scanning tunneling microscopy studies. Mapping the spatially dependent electronic structure of graphene in the presence of charged impurities unveils the unique behavior of its relativistic charge carriers in response to a local Coulomb potential.

Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees ...

Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using visible light irradiation with plasmonic nanoparticles. The plasmonic nanoparticle is used to improve the reduction efficiency of GO. It only takes 30 min&#160;at RT by illuminating the solutions with Xe-lamp, the r-GO solutions can be obtained by completely removing gold nanoparticles through simple centrifugation step. The spherical gold nanoparticles (AuNPs) as compared to the other nanostructures is the most suitable plasmonic nanostructure for r-GO preparation. The reduced graphene oxide prepared using visible light and AuNPs was equally qualitative as chemically reduced graphene oxide, which was supported by various analytical techniques such as UV-Vis spectroscopy, Raman spectroscopy, powder XRD and XPS. The reduced graphene oxide prepared with visible light shows excellent quenching properties over the fluorescent molecules modified on ssDNA and excellent fluorescence recovery for target DNA detection. The r-GO prepared by recycled AuNPs is found to be of same quality with that of chemically reduced r-GO. The use of visible light with plasmonic nanoparticle demonstrates the good alternative method for r-GO synthesis.

A simple protocol for the preparation of reduced graphene oxide using visible light and plasmonic nanoparticle is described.

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using ...

Synthesis and Functionalization of 3D Nano-graphene Materials: Graphene Aerogels and Graphene Macro Assemblies

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. Additionally, most reported graphene assemblies are held together through physical interactions (e.g., van der Waals forces) rather than chemical bonds, which limit their mechanical strength and conductivity. This video method details recently developed strategies to fabricate mass-producible, graphene-based bulk materials derived from either polymer foams or single layer graphene oxide. These materials consist primarily of individual graphene sheets connected through covalently bound carbon linkers. They maintain the favorable properties of graphene such as high surface area and high electrical and thermal conductivity, combined with tunable pore morphology and exceptional mechanical strength and elasticity. This flexible synthetic method can be extended to the fabrication of polymer/carbon nanotube (CNT) and polymer/graphene oxide (GO) composite materials. Furthermore, additional post-synthetic functionalization with anthraquinone is described, which enables a dramatic increase in charge storage performance in supercapacitor applications.

This video method describes the synthesis of high surface area, monolithic 3D graphene-based materials derived from polymer precursors as well as single layer graphene oxide.

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. ...

Effect of Bending on the Electrical Characteristics of Flexible Organic Single Crystal-based Field-effect Transistors

The charge transport in an organic semiconductor depends highly on the molecular packing in the crystal, which influences the electronic coupling immensely. However, in soft electronics, in which organic semiconductors play a critical role, the devices will be bent or folded repeatedly. The effect of bending on the crystal packing and thus the charge transport is crucial to the performance of the device. In this manuscript, we describe the protocol to bend a single crystal of 5,7,12,16-tetrachloro-6,13-diazapentacene (TCDAP) in the field-effect transistor configuration and to obtain reproducible I-V characteristics upon bending the crystal. The results show that bending a field-effect transistor prepared on a flexible substrate results in nearly reversible yet opposite trends in charge mobility, depending on the bending direction. The mobility increases when the device is bent toward the top gate/dielectric layer (upward, compressive state) and decreases when bent toward the crystal/substrate side (downward, tensile state). The effect of bending curvature was also observed, with greater mobility change resulting from higher bending curvature. It is suggested that the intermolecular &#960;-&#960; distance changes upon bending, thereby influencing the electronic coupling and the subsequent carrier transport ability.

This manuscript describes the bending process of an organic single crystal-based field-effect transistor to maintain a functioning device for electronic property measurement. The results suggest that bending causes changes in the molecular spacing in the crystal and thus in the charge hopping rate, which is important in flexible electronics.

The charge transport in an organic semiconductor depends highly on the molecular packing in the crystal, which influences the electronic coupling ...

Atmospheric Pressure Fabrication of Large-Sized Single-Layer Rectangular SnSe Flakes

Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for applications in two-dimensional nanoelectronics devices. Although many methods to synthesize SnSe nanocrystals have been developed, a simple way to fabricate large-sized single-layer SnSe flakes remains a great challenge. Herein, we show the experimental method to directly grow large-sized single-layer rectangular SnSe flakes on commonly used SiO2/Si insulating substrates using a straightforward two-step fabrication method in an atmospheric pressure quartz tube furnace system. The single-layer rectangular SnSe flakes with an average thickness of ~6.8 &#197; and lateral dimensions of about 30 &#181;m &#215; 50 &#181;m were fabricated by a combination of vapor transport deposition technique and nitrogen etching route. We characterized the morphology, microstructure, and electrical properties of the rectangular SnSe flakes and obtained excellent crystallinity and good electronic properties. This article about the two-step fabrication method can help researchers grow other similar two-dimensional, large-sized, single-layer materials using an atmospheric pressure system.

A protocol is presented demonstrating a two-step fabrication technique to grow large-sized single-layer rectangular shaped SnSe flakes on low-cost SiO2/Si dielectrics wafers in an atmospheric pressure quartz tube furnace system.

Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for ...

Guidelines and Experience Using Imaging Biomarker Explorer (IBEX) for Radiomics

Imaging Biomarker Explorer (IBEX) is an open-source tool for medical imaging radiomics work. The purpose of this paper is to describe how to use IBEX's graphical user interface (GUI) and to demonstrate how IBEX calculated features have been used in clinical studies. IBEX allows for the import of DICOM images with DICOM radiation therapy structure files or Pinnacle files. Once the images are imported, IBEX has tools within the Data Selection GUI to manipulate the viewing of the images, measure voxel values and distances, and create and edit contours. IBEX comes with 27 preprocessing and 132 feature choices to design feature sets. Each preprocessing and feature category has parameters that can be altered. The output from IBEX is a spreadsheet that contains: 1) each feature from the feature set calculated for each contour in a data set, 2) image information about each contour in a data set, and 3) a summary of the preprocessing and features used with their selected parameters. Features calculated from IBEX have been used in studies to test the variability of features under different imaging conditions and in survival models to improve current clinical models.

Guidelines and Experience Using Imaging Biomarker Explorer IBEX for Radiomics

We describe IBEX, an open-source tool designed for medical imaging radiomics studies, and how to use this tool. In addition, some published works that have used IBEX for uncertainty analysis and model building are showcased.

Imaging Biomarker Explorer (IBEX) is an open-source tool for medical imaging radiomics work. The purpose of this paper is to describe how to use IBEX's ...

Fabrication of Three-Dimensional Graphene-Based Polyhedrons via Origami-Like Self-Folding

The assembly of two-dimensional (2D) graphene into three-dimensional (3D) polyhedral structures while preserving the graphene's excellent inherent properties has been of great interest for the development of novel device applications. Here, fabrication of 3D, microscale, hollow polyhedrons (cubes) consisting of a few layers of 2D graphene or graphene oxide sheets via an origami-like self-folding process is described. This method involves the use of polymer frames and hinges, and aluminum oxide/chromium protection layers that reduce tensile, spatial, and surface tension stresses on the graphene-based membranes when the 2D nets are transformed into 3D cubes. The process offers control of the size and shape of the structures as well as parallel production. In addition, this approach allows the creation of surface modifications by metal patterning on each face of the 3D cubes. Raman spectroscopy studies show the method allows the preservation of the intrinsic properties of the graphene-based membranes, demonstrating the robustness of our method.

Fabrication of Three-Dimensional Graphene-Based Polyhedrons via Origami-Like Self-Folding

Here, we present a protocol for fabrication of 3D graphene-based polyhedrons via origami-like self-folding.

The assembly of two-dimensional (2D) graphene into three-dimensional (3D) polyhedral structures while preserving the graphene's excellent inherent ...

Preparation of Graphene Liquid Cells for the Observation of Lithium-ion Battery Material

In this work, we introduce the preparation of graphene liquid cells (GLCs), encapsulating both electrode materials and organic liquid electrolytes between two graphene sheets, and the facile synthesis of one-dimensional nanostructures using electrospinning. The GLC enables in situ transmission electron microscopy (TEM) for the lithiation dynamics of electrode materials. The in situ GLC-TEM using an electron beam for both imaging and lithiation can utilize not only realistic battery electrolytes, but also the high-resolution imaging of various morphological, phase, and interfacial transitions.

Here, we present a protocol for the fabrication and preparation of a graphene liquid cell for in situ transmission electron microscopy observation, along with a synthesis of electrode materials and electrochemical battery cell tests.

In this work, we introduce the preparation of graphene liquid cells (GLCs), encapsulating both electrode materials and organic liquid electrolytes between ...