Thanks to XG Sciences for generous donations of graphene paper. Thanks to Dr. C. Friedrich for generously letting us use the micro-drilling equipment. A special thanks is extended to Tayloria Adams for narrating the video.

1. Fabricate a Laminated Electrode/insulation 3D Structure
<ol>
	<li>For a 6 graphene layer, 5 tape layer device, cut graphene paper with a scalpel or similar razor blade and straight-edged ruler into six 0.7 cm x&#160;1.5 cm rectangles and use scissors to cut double-sided pressure-sensitive tape into five 1.3 cm x&#160;~5 cm stripes. 
	NOTE: As shown in Figure 1a, this yields a 3 ground electrode, 3 AC signal electrode device. The 7 mm conducting layer width is narrow enough to fit onto a glass slide, yet wide enough for easy drilling. The 2 mm length does not easily break upon repeated use and has sufficient room to attach copper wires. The device depth is limited by end mill depths.</li>
	<li>Lay the first layer of graphene paper on a clean glass slide. Slowly cover one end of the graphene paper with one stripe of tape, leaving a ~2 mm margin to assure insulation between the two adjacent graphene paper layers (Figure 1b).</li>
	<li>Place the second layer of graphene paper on the top of the tape offset to the first layer of graphene paper (Figure 1a). Apply moderate pressure (press uniformly with thumb, ~100 N over 0.7 cm2 area) after addition of each conducting layer to ensure good sealing between layers.</li>
	<li>Repeat steps 1.2 and 1.3 for the remaining layers, leaving both the top and bottom layers graphene paper. Cut along the dotted line shown in Figure 1b to remove the excess tape from the device edges leaving a small ~1 mm margin to assure sealed insulation between graphene paper layers (Figure 1b). 
	NOTE: Double-sided tape is not utilized as the top and bottom layers to avoid collecting debris as this laminated structure is drilled, mounted on a slide, and filled with sample.</li>
	<li>Perform a quick insulation test with a multimeter (resistance mode). Position the positive and negative probes on two different sides of the device (A and B on Figure 1c); high resistance (kilo- to mega-Ohms) indicates good insulation between layers. Remove the layered structure from the glass slide to prepare for micro-well drilling. 
	NOTE: A device typically fails the insulation test when adjacent graphene paper layers make contact during steps 1.2 through 1.4. Discard such devices.</li>
</ol>
2. Drill Micro-well in the Laminated Structure
<ol>
	<li>Use a computer-controlled mechanical micro-milling machine and choose an end mill with a 700 &#181;m in diameter and 2.1 mm length of cut. Immobilize the laminated structure on the micro-milling stage using appropriate clamps (Figures 2a and b). Run the milling machine spindle at 8,600 rpm, then lower the end mill slowly into and through the center of the laminated structure. Move the rotating end mill up and down through the micro-well to smooth the inside wall.
	<ol>
		<li>Choose micro-well diameters, which are constrained by available end mill diameter/length of cut aspect ratios. Ensure that the inner surface of micro-well is as vertical and clean as possible for optimal electric field gradients and light passage through the micro-well.</li>
	</ol>
	</li>
	<li>Clean debris from micro-well with pressurized air. Perform another insulation test as described in 1.5.</li>
</ol>
3. Attach Electrical Leads to the Laminated Structure
<ol>
	<li>Fold two 3 cm long 32 G&#160;copper wires to a right angle at 2 cm. Mix ~1.5 ml of part A and B of silver conductive epoxy. 
	NOTE: <img alt="Equation 1" fo:content-width="3in" src="/files/ftp_upload/51696/51696eq1.jpg" /></li>
	<li>Manually apply mixed silver epoxy to the top and the tips of all 3 graphene paper layers to assure good contact between layers on side A of the laminated structure (Figure 1c), then place the 1 cm copper wire end in the epoxy and between any two layers. Softly squeeze the layers to remove excess epoxy and assure good electrical contact. Repeat for side B of the laminated structure.</li>
	<li>Place the whole device in oven rack, to dry overnight&#160; 70 &#176;C at and 1 atm.</li>
</ol>
4. Prepare Sample and Media
<ol>
	<li>Prepare isotonic media of a spectrum of conductivities using the conductivity meter, 290 mM mannitol stock solution and serial additions of isotonic phosphate buffer saline (PBS). 
	NOTE: A linear correlation exists between the conductivity and volume concentration of ~290 mOsm/L PBS (conducting) in ~290 mOsm/L mannitol solution (non-conducting). The video features a medium of 0.01 S/m conductivity.</li>
	<li>Mix polystyrene beads with prepared conductivity media or e-pure water (~5 x 10-6 S/m) to a 1:50 vol:vol ratio. This protocol is easily adaptable to biological cells as well.</li>
</ol>
5. Setup Experiment and Operate Device
<ol>
	<li>Clamp the device onto a glass slide with moderate pressure (Figure 2d) using modified paper clamps or equivalent. The footings should be close enough to the micro-well to seal the laminated structure to the glass slide preventing sample leakage. The clamp should fit within the microscope stage with pressure optimized to a) prevent deformation of the laminated structure, and b) ensure the micro-well fluid does not leak. Deformation alters the well geometry and light path reducing experiment reproducibility.</li>
	<li>Using a micro syringe or equivalent, slowly inject ~1 &#181;l&#160;of the sample into the micro-well and avoid introducing any bubbles. Repeat injection if necessary and use care to not damage the micro-well walls with the sharp needle. Slightly overfill the micro-well and immediately slide cover glass over the micro-well to remove excess fluid, prevent evaporation, and ensure reproducible volumes for each experiment. 
	NOTE: A diamond tip glasscutter works well to score and crack cover glass to size.</li>
	<li>Secure the completed laminated microdevice to the microscope stage and attach the function generator electrode wires to the two copper leads on the device. In AxioVision (Zeiss software), click button to start the camera recording in multidimensional acquisition mode. Initiate function generator signal at a fixed time period after starting the CCD camera recording to document responses with and without the electric field applied. 
	NOTE: Here 100 Hz to 10 MHz frequency with a 15 Vpeak-peak signal were applied and experiments were observed at 10X magnification at 1 to 200 above the glass slide surface for 2 sec&#160;without field and ~5 min&#160;with field applied. Images were digitally saved at 1 to 5 frames per sec&#160;(fps) for further analysis.</li>
	<li>Upon experiment completion, remove the device and dismantle the clamps. Immerse both the glass slide and device in soapy water, then rinse well. Reuse devices about 30 times with consistent performance.</li>
</ol>
6. Data Analysis and&#160;Image Processing
<ol>
	<li>Analyze image data with preferred software, such as ImageJ. Calculate velocity from the particle displacement between consecutive images at a given time step.</li>
	<li>Calculate experimental DEP force and field strength based on velocity to compile trends and compare with theory29.</li>
	<li>Measure particle velocity radially in the micro-well geometry consistent with the shape of the electric field gradient. From the micro-well edge to the center, identify 8 concentric isoelectric contours (350, 300,&#8230;50, 0 &#181;m), which results in 7 regions. 
	NOTE: The time for particles to traverse the 50 &#181;m distance was used to calculate velocity. When geometric variations necessitated it, the isoelectric contours were adjusted slightly.</li>
</ol>

The authors have no conflicts to disclose.

This manuscript details protocols for fabricating a novel 6 graphene layer and 5 tape layer microdevice. Further, device operation is illustrated via observed DEP behaviors of 6.08 &#181;m polystyrene beads along with a unique, geometrically relevant particle velocity analysis approach. This versatile approach to construct nonlinear electrokinetic devices is less costly than electrode and fluidic layer microfabrication techniques, while yielding equally reliable results.
Further, this novel 3D...

Graphene is a novel material known for its high quality electronic properties and potential chemical and biosensor applications1. Graphene nanoplatelets have been used for catalyst support2,3, biosensors4, super-capacitors5, and composite-electrodes including graphene/polyaniline and silicon nanoparticle/graphene composites6-8. This manuscript describes utilization of graphene paper as electrodes in a unique three-dimensional (3D), layered microfluidic device. Graphene paper electrodes were laminated with insulative double-sided tape and a chamber drilled within which 3D AC dielectrophoresis of polystyrene beads was performed.
Dielectrophoresis (DEP) refers to the movement of polarizable particles under non-uniform electrical fields. Positive DEP (pDEP) or negative DEP (nDEP) occurs when particles are more or less polarizable than the surrounding medium, resulting in movement toward the strongest or weakest electrical field, respectively. This nonlinear electrokinetic tool has been used for separation, sorting, trapping, and identification of particles and biological cells9-15. The dielectrophoretic force experienced by a polarized particle is a function of the electric field gradient, particle radius and shape, particle dielectric properties including conductivity and permittivity, as well as the media conductivity and permittivity. In traditional two-dimensional (2D) DEP, particle movement is in the primary plane of the electric field gradient typically formed between microfabricated surface electrodes; movement in the vertical direction is negligible compared to in-plane directions in most devices. However, harnessing this third dimension of electrical field gradients for 3D DEP allows for higher sample throughput and increases the versatility to design new and improved dielectrophoretic separations in which the flow is traverse to the field gradients16,17. Other specific designs include 3D insulator-based DEP18, 3D carbon-electrode DEP13,19, and 3D electroplating DEP10. As evidenced by the research into 3D structures, such devices can be operated in continuous flow mode to achieve higher throughputs. Observation of the 3D particle movement in our layered 3D device is achieved as a function of frequency and medium conductivity via light microscopy at different focal heights.
Fatoyinbo&#160;et al. first reported DEP in a 3D laminated electrode/insulation structure using alternatively stacked 30 &#956;m aluminum foil and 150 &#956;m epoxy resin films20. Hubner&#160;et al. then designed similar 3D laminated electrodes with 35 &#956;m copper tape and 118 &#956;m polyimide adhesive21. This work borrows the 3D-well design22,23, and uniquely utilizes the convenience of 50 &#956;m graphene paper as the conducting layers and 100 &#956;m double-sided tape as the insulating layers, which achieved sealing and sufficient electrical shielding. Graphene paper versatility is a distinct advantage for 3D electrode microdevices because the graphene nanoplatelets have the ability to concurrently act as biosensors, which this group previously demonstrated24.
The field gradients achieved within the graphene paper/polymer laminated 3D microdevices depend on the micro-well dimensions, the graphene paper layers, and the applied electric field. Critical dimensions include the vertical electrode spacing (conducting and insulating layer thicknesses) and micro-well diameter and height (determined by layers stacked). The electric signal can be tuned via amplitude and frequency. The current device structure is for batch operation, but can be tailored to a continuous flow device. The device fabrication technique described here is suitable for developing 3D laminated electrodes with a wide variety of graphene nanoplatelet properties simply by exchanging the graphene paper utilized. Advantages of utilizing graphene paper are versatility of physical and chemical properties, reduced expense, and the graphene nanoplatelets can concurrently act as biosensors to detect a wide range of bioanalytes24. Long-term goals of high throughput 3D DEP systems are to rapidly identify cell types25-27, or achieve label-free, electrically mediated cell sorting of diseased cells from populations of healthy cells28. This paper demonstrates material optimization and device preparation and operation followed by illustration and analysis of typical results.

<table><tbody><tr><td>Polystyrene Beads</td><td>Spherotech, Inc.</td><td>PP-60-10</td><td>6.08 &amp;mu;m diameter</td></tr><tr><td>Graphene paper</td><td>XG Sciences, Inc.</td><td>XG Leaf B-072</td><td></td></tr><tr><td>Double sided tape</td><td>3M</td><td>N/A</td><td>136 office tape</td></tr><tr><td>Silver conductive epoxy</td><td>MG chemicals</td><td>8331-14G</td><td>Part A &amp;amp; B included</td></tr><tr><td>Mannitol</td><td>Sigma Aldrich</td><td>091M0020V</td><td></td></tr><tr><td>Phosphate buffer saline</td><td>OmniPur</td><td>0381C490</td><td></td></tr><tr><td>Microscope (CCD Camera)</td><td>Zeiss</td><td>Axiovert 200M</td><td></td></tr><tr><td>Function/waveform generator</td><td>Agilent</td><td>33250A</td><td></td></tr><tr><td>Syringe</td><td>Hamilton</td><td>84505</td><td></td></tr><tr><td>Paper Clamp</td><td>ADAMS</td><td>3300-50-3848</td><td></td></tr><tr><td>Oven</td><td>Fisher Scientific</td><td>280A</td><td></td></tr><tr><td>Multimeter</td><td>OMEGA</td><td>HHM25</td><td></td></tr><tr><td>Micro-milling machine</td><td>AEROTECH</td><td>ABL1500 stages/A3200 Npaq controller</td><td></td></tr><tr><td>End mill</td><td>ULTRATOOL</td><td>708473</td><td></td></tr><tr><td>AxioVision</td><td>Zeiss</td><td>Version 4.8</td><td></td></tr></tbody></table>

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.

Dielectrophoretic experiments on 6&#160;&#181;m polystyrene beads were conducted in a 0.38 mm3 cylindrical micro-well. Results demonstrate that a 3D laminated graphene paper-based device can illustrate similar dielectrophoretic signatures as 3D metal foil laminated devices20,21, traditional 2D metal-electrode26,27, and 2D insulator devices25. In the following experiments, an 15 Vpeak-peak AC signal was applied and frequency...

Watch this Scientific Journal Video about Development of a 3D Graphene Electrode Dielectrophoretic Device at JoVE.com

Development of a 3D Graphene Electrode Dielectrophoretic Device

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 ...

development-of-a-3d-graphene-electrode-dielectrophoretic-device

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11.9K Views.  Michigan Technological University.  Een micro-inrichting met hoge doorvoer potentieel gebruikt om driedimensionale (3D) diëlektroforese (DEP) tonen met nieuwe materialen. Grafeen nanoplatelet papier en dubbelzijdig tape werden afwisselend gestapeld; een 700 urn micro-put werd geboord dwars op de lagen. DEP gedrag polystyreen korrels werd aangetoond in de micro-put. 

Video: Development of a 3D Graphene Electrode Dielectrophoretic Device

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 ...

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. ...

Flow-assisted Dielectrophoresis: A Low Cost Method for the Fabrication of High Performance Solution-processable Nanowire Devices

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of nanowires. DEP is used for nanowire analysis, characterization, and for solution-based fabrication of semiconducting devices. The method works by applying an alternating electric field between metallic electrodes. The nanowire formulation is then dropped onto the electrodes which are on an inclined surface to create a flow of the formulation using gravity. The nanowires then align along the gradient of the electric field and in the direction of the liquid flow. The frequency of the field can be adjusted to select nanowires with superior conductivity and lower trap density. 
In this work, flow-assisted DEP is used to create nanowire field effect transistors. Flow-assisted DEP has several advantages: it allows selection of nanowire electrical properties; control of nanowire length; placement of nanowires in specific areas; control of orientation of nanowires; and control of nanowire density in the device. 
The technique can be expanded to many other applications such as gas sensors and microwave switches. The technique is efficient, quick, reproducible, and it uses a minimal amount of dilute solution making it ideal for the testing of novel nanomaterials. Wafer scale assembly of nanowire devices can also be achieved using this technique, allowing large numbers of samples for testing and large-area electronic applications.

In this paper, flow assisted dielectrophoresis is demonstrated for the self-assembly of nanowire devices. The fabrication of a silicon nanowire field effect transistor is shown as an example.

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of ...

Using Graphene Liquid Cell Transmission Electron Microscopy to Study in Situ Nanocrystal Etching

Graphene liquid cell electron microscopy provides the ability to observe nanoscale chemical transformations and dynamics as the reactions are occurring in liquid environments. This manuscript describes the process for making graphene liquid cells through the example of graphene liquid cell transmission electron microscopy (TEM) experiments of gold nanocrystal etching. The protocol for making graphene liquid cells involves coating gold, holey-carbon TEM grids with chemical vapor deposition graphene and then using those graphene-coated grids to encapsulate liquid between two graphene surfaces. These pockets of liquid, with the nanomaterial of interest, are imaged in the electron microscope to see the dynamics of the nanoscale process, in this case the oxidative etching of gold nanorods. By controlling the electron beam dose rate, which modulates the etching species in the liquid cell, the underlying mechanisms of how atoms are removed from nanocrystals to form different facets and shapes can be better understood. Graphene liquid cell TEM has the advantages of high spatial resolution, compatibility with traditional TEM holders, and low start-up costs for research groups. Current limitations include delicate sample preparation, lack of flow capability, and reliance on electron beam-generated radiolysis products to induce reactions. With further development and control, graphene liquid cell may become a ubiquitous technique in nanomaterials and biology, and is already being used to study mechanisms governing growth, etching, and self-assembly processes of nanomaterials in liquid on the single particle level.

Using Graphene Liquid Cell Transmission Electron Microscopy to Study in Situ Nanocrystal Etching

Graphene liquid cell electron microscopy can be used to observe nanocrystal dynamics in a liquid environment with greater spatial resolution than other liquid cell electron microscopy techniques. Etching premade nanocrystals and following their shape using graphene liquid cell Transmission Electron Microscopy can yield important mechanistic information about nanoparticle transformations.

Graphene liquid cell electron microscopy provides the ability to observe nanoscale chemical transformations and dynamics as the reactions are occurring in ...

Chemistry

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 ...

Production of a Strain-Measuring Device with an Improved 3D Printer

A traditional strain measurement sensor needs to be electrified and is susceptible to electromagnetic interference. In order to solve the fluctuations in the analog electrical signal in a traditional strain gauge operation, a new strain measurement method is presented here. It uses a photographic technique to display the strain change by amplifying the change of the pointer displacement of the mechanism. A visual polydimethylsiloxane (PDMS) lens with a focal length of 7.16 mm was added to a smartphone camera to generate a lens group acting as a microscope to capture images. It had an equivalent focal length of 5.74 mm. Acrylonitrile butadiene styrene (ABS) and nylon amplifiers were used to test the influence of different materials on the sensor performance. The production of the amplifiers and PDMS lens is based on improved 3D printing technology. The data obtained were compared with the results from finite element analysis (FEA) to verify their validity. The sensitivity of the ABS amplifier was 36.03 &plusmn; 1.34 &#181;&epsilon;/&#181;m, and the sensitivity of the nylon amplifier was 36.55 &plusmn; 0.53 &#181;&epsilon;/&#181;m.

This work presents a strain measurement sensor consisting of an amplification mechanism and a polydimethylsiloxane microscope manufactured using an improved 3D printer.

A traditional strain measurement sensor needs to be electrified and is susceptible to electromagnetic interference. In order to solve the fluctuations in ...

Evaluating the Electrochemical Properties of Supercapacitors using the Three-Electrode System

The three-electrode system is a basic and general analytical platform for investigating the electrochemical performance and characteristics of energy storage systems at the material level. Supercapacitors are one of the most important emergent energy storage systems developed in the past decade. Here, the electrochemical performance of a supercapacitor was evaluated using a three-electrode system with a potentiostat device. The three-electrode system consisted of a working electrode (WE), reference electrode (RE), and counter electrode (CE). The WE is the electrode where the potential is controlled and the current is measured, and it is the target of research. The RE acts as a reference for measuring and controlling the potential of the system, and the CE is used to complete the closed circuit to enable electrochemical measurements. This system provides accurate analytical results for evaluating electrochemical parameters such as the specific capacitance, stability, and impedance through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Several experimental design protocols are proposed by controlling the parameter values of the sequence when using a three-electrode system with a potentiostat device to evaluate the electrochemical performance of supercapacitors. Through these protocols, the researcher can set up a three-electrode system to obtain reasonable electrochemical results for assessing the performance of supercapacitors.

The protocol describes the evaluation of various electrochemical properties of supercapacitors using a three-electrode system with a potentiostat device.

The three-electrode system is a basic and general analytical platform for investigating the electrochemical performance and characteristics of energy ...

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 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, ...

Coating CryoEM Grids with Monolayer Graphene to Improve Cryo-Sample Preparation

Application of Monolayer Graphene to Cryo-Electron Microscopy Grids for High-resolution Structure Determination

In cryogenic electron microscopy (cryoEM), purified macromolecules are applied to a grid bearing a holey carbon foil; the molecules are then blotted to remove excess liquid and rapidly frozen in a roughly 20-100 nm thick layer of vitreous ice, suspended across roughly 1 &#181;m wide foil holes. The resulting sample is imaged using cryogenic transmission electron microscopy, and after image processing using suitable software, near-atomic resolution structures can be determined. Despite cryoEM&#39;s widespread adoption, sample preparation remains a severe bottleneck in cryoEM workflows, with users often encountering challenges related to samples behaving poorly in the suspended vitreous ice. Recently, methods have been developed to modify cryoEM grids with a single continuous layer of graphene, which acts as a support surface that often increases particle density in the imaged area and can reduce interactions between particles and the air-water interface. Here, we provide detailed protocols for the application of graphene to cryoEM grids and for rapidly assessing the relative hydrophilicity of the resulting grids. Additionally, we describe an EM-based method to confirm the presence of graphene by visualizing its characteristic diffraction pattern. Finally, we demonstrate the utility of these graphene supports by rapidly reconstructing a 2.7 &#197; resolution density map of a Cas9 complex using a pure sample at a relatively low concentration.

Author Spotlight: Enhancing CryoEM Sample Preparation Using Graphene Monolayer on Microscopy Grids 

The application of support layers to cryogenic electron microscopy (cryoEM) grids can increase particle density, limit interactions with the air-water interface, reduce beam-induced motion, and improve the distribution of particle orientations. This paper describes a robust protocol for coating cryoEM grids with a monolayer of graphene for improved cryo-sample preparation.

In cryogenic electron microscopy (cryoEM), purified macromolecules are applied to a grid bearing a holey carbon foil; the molecules are then blotted to ...

Development of a 3D Graphene Electrode Dielectrophoretic Device

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