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 border="0" cellpadding="0" cellspacing="0" width="552">
	<tbody>
		<tr>
			<td>Reagents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Name of Reagent</td>
			<td>Company</td>
			<td>Catalogue Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Polystyrene Beads</td>
			<td>Spherotech, Inc.</td>
			<td>PP-60-10</td>
			<td>6.08 um 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 &#38;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></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Equipment:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Name of equipment&#160;</td>
			<td>Company</td>
			<td>Catalogue Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Microscope&#160;&#160;&#160;&#160; (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>Version4.8</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

Research

JoVE Journal

Engineering

11.9K Views.  Michigan Technological University. 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 μm micro-well was drilled transverse to the layers. DEP behavior of polystyrene beads was demonstrated in the micro-well.

Video: Development of a 3D Graphene Electrode Dielectrophoretic Device

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

High-resolution, High-speed, Three-dimensional Video Imaging with Digital Fringe Projection Techniques

Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces.&#160;Like the human eyes and brain, DFP uses triangulation between matching points in two views of the same scene at different angles to compute depth.&#160;However, unlike a stereo-based method, DFP uses a digital video projector to replace one of the cameras1. The projector rapidly projects a known sinusoidal pattern onto the subject, and the surface of the subject distorts these patterns in the camera&#8217;s field of view. Three distorted patterns (fringe images) from the camera can be used to compute the depth using triangulation.
Unlike other 3D measurement methods, DFP techniques lead to systems that tend to be faster, lower in equipment cost, more flexible, and easier to develop.&#160;DFP systems can also achieve the same measurement resolution as the camera.&#160;For this reason, DFP and other digital structured light techniques have recently been the focus of intense research (as summarized in1-5). Taking advantage of DFP, the graphics processing unit, and optimized algorithms, we have developed a system capable of 30&#160;Hz 3D video data acquisition, reconstruction, and display for over 300,000 measurement points per frame6,7.&#160;Binary defocusing DFP methods can achieve even greater speeds8.
Diverse applications can benefit from DFP techniques. Our collaborators have used our systems for facial function analysis9, facial animation10, cardiac mechanics studies11, and fluid surface measurements, but many other potential applications exist.&#160;This video will teach the fundamentals of DFP techniques and illustrate the design and operation of a binary defocusing DFP system.

This video describes the fundamentals of digital fringe projection techniques, which provide dense 3D measurements of dynamically changing surfaces.&#160;It also demonstrates the design and operation of a high-speed binary defocusing system based on these techniques.

Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces.&#160;Like the human eyes and brain, DFP uses ...

Ultrasound Velocity Measurement in a Liquid Metal Electrode

A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently more difficult than measuring the flow of a transparent fluid, since optical methods are not applicable. Ultrasound can be used to measure the velocity of an opaque fluid, not only at isolated points, but at hundreds or thousands of points arrayed along lines, with good temporal resolution. When applied to a liquid metal electrode, ultrasound velocimetry involves additional challenges: high temperature, chemical activity, and electrical conductivity. Here we describe the experimental apparatus and methods that overcome these challenges and allow the measurement of flow in a liquid metal electrode, as it conducts current, at operating temperature. Temperature is regulated within &#177;2 &#176;C using a Proportional-Integral-Derivative (PID) controller that powers a custom-built furnace. Chemical activity is managed by choosing vessel materials carefully and enclosing the experimental setup in an argon-filled glovebox. Finally, unintended electrical paths are carefully prevented. An automated system logs control settings and experimental measurements, using hardware trigger signals to synchronize devices. This apparatus and these methods can produce measurements that are impossible with other techniques, and allow optimization and control of electrochemical technologies like liquid metal batteries.

Ultrasound velocimetry is used to study mixing by fluid flow in liquid metal electrodes. The focus of this manuscript is to illustrate the methods used for making precise, spatially-resolved ultrasound measurements while limiting oxidation and controlling and monitoring temperature, applied current, and the heater power being supplied.

A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently ...

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

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. ...

Non-aqueous Electrode Processing and Construction of Lithium-ion Coin Cells

Research into new and improved materials to be utilized in lithium-ion batteries (LIB) necessitates an experimental counterpart to any computational analysis. Testing of lithium-ion batteries in an academic setting has taken on several forms, but at the most basic level lies the coin cell construction. In traditional LIB electrode preparation, a multi-phase slurry composed of active material, binder, and conductive additive is cast out onto a substrate. An electrode disc can then be punched from the dried sheet and used in the construction of a coin cell for electrochemical evaluation. Utilization of the potential of the active material in a battery is critically dependent on the microstructure of the electrode, as an appropriate distribution of the primary components are crucial to ensuring optimal electrical conductivity, porosity, and tortuosity, such that electrochemical and transport interaction is optimized. Processing steps ranging from the combination of dry powder, wet mixing, and drying can all critically affect multi-phase interactions that influence the microstructure formation. Electrochemical probing necessitates the construction of electrodes and coin cells with the utmost care and precision. This paper aims at providing a step-by-step guide of non-aqueous electrode processing and coin cell construction for lithium-ion batteries within an academic setting and with emphasis on deciphering the influence of drying and calendaring.

Non-aqueous electrode processing is central to the construction of coin cells and the evaluation of new electrode chemistries for lithium-ion batteries. A step-by-step guide to the basic practices needed as an electrochemical engineer working with batteries in an academic experimental setting is furnished.

Research into new and improved materials to be utilized in lithium-ion batteries (LIB) necessitates an experimental counterpart to any computational ...

A 3D-printed Chamber for Organic Optoelectronic Device Degradation Testing

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, using 3D-printing. As these types of devices are sensitive to moisture and oxygen, such a chamber can aid researchers in characterizing the electronic and stability properties. The chamber is intended to be used as a temporary, reusable, and stable environment with controlled properties (including humidity, gas introduction, and temperature). It can be used to protect air-sensitive materials or to expose them to contaminants in a controlled way for degradation studies. To characterize the properties of the chamber, we outline a simple procedure to determine the water vapor transmission rate (WVTR) using relative humidity as measured by a standard humidity sensor. This standard operating procedure, using a 50% infill density of polylactic acid (PLA), results in a chamber that can be used for weeks without any significant loss of device properties. The versatility and ease of use of the chamber allows it to be adapted to any characterization condition that requires a compact-controlled atmosphere.

Here, we present a protocol for the design, manufacture, and use of a simple, versatile 3D-printed and controlled atmospheric chamber for the optical and electrical characterization of air-sensitive organic optoelectronic devices.

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, ...

Three-electrode Coin Cell Preparation and Electrodeposition Analytics for Lithium-ion Batteries

As lithium-ion batteries find use in high energy and power applications, such as in electric and hybrid-electric vehicles, monitoring the degradation and subsequent safety issues becomes increasingly important. In a Li-ion cell setup, the voltage measurement across the positive and negative terminals inherently includes the effect of the cathode and anode which are coupled and sum to the total cell performance. Accordingly, the ability to monitor the degradation aspects associated with a specific electrode is extremely difficult because the electrodes are fundamentally coupled. A three-electrode setup can overcome this problem. By introducing a third (reference) electrode, the influence of each electrode can be decoupled, and the electrochemical properties can be measured independently. The reference electrode (RE) must have a stable potential that can then be calibrated against a known reference, for example, lithium metal. The three-electrode cell can be used to run electrochemical tests such as cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). Three-electrode cell EIS measurements can elucidate the contribution of individual electrode impedance to the full cell. In addition, monitoring the anode potential allows the detection of electrodeposition due to lithium plating, which can cause safety concerns. This is especially important for the fast charging of Li-ion batteries in electric vehicles. In order to monitor and characterize the safety and degradation aspects of an electrochemical cell, a three-electrode setup can prove invaluable. This paper aims to provide a guide to constructing a three-electrode coin cell setup using the 2032-coin cell architecture, which is easy to produce, reliable, and cost-effective.

Three-electrode cells are useful in studying the electrochemistry of lithium-ion batteries. Such an electrochemical setup allows the phenomena associated with the cathode and anode to be decoupled and examined independently. Here, we present a guide for construction and use of a three-electrode coin cell with emphasis on lithium plating analytics.

As lithium-ion batteries find use in high energy and power applications, such as in electric and hybrid-electric vehicles, monitoring the degradation and ...

A Standard and Reliable Method to Fabricate Two-Dimensional Nanoelectronics

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D materials is still in nascent stages, scientists cannot fully rely on traditional semiconductor techniques for related research. Delicate processes from locating the materials to electrode definition need to be well controlled. In this article, a universal fabrication protocol required in manufacturing nanoscale electronics, such as 2D quasi-heterojunction bipolar transistors (Q-HBT), and 2D back-gated transistors are demonstrated. This protocol includes the determination of material position, electron beam lithography (EBL), metal electrode definition, et al. A step by step narrative of the fabrication procedures for these devices are also presented. Furthermore, results show that each of the fabricated devices has achieved high performance with high repeatability. This work reveals a comprehensive description of process flow for preparing 2D nano-electronics, enables the research groups to access this information, and pave the way toward future electronics.

The article aims to introduce a standard and reliable fabrication procedure for the development of future low dimensional nanoelectronics.

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...