Name: fabrication of nanoheight channels incorporating surface acoustic wave actuation via lithium niobate for acoustic nanofluidics
Uploaded: 2020-02-05T13:30:00
Description: Watch this Scientific Journal Video about Fabrication of Nanoheight Channels Incorporating Surface Acoustic Wave Actuation via Lithium Niobate for Acoustic Nanofluidics at JoVE.com

The authors are grateful to the University of California and the NANO3 facility at UC San Diego for provision of funds and facilities in support of this work. This work was performed in part at the San Diego Nanotechnology Infrastructure (SDNI) of UCSD, a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the National Science Foundation (Grant ECCS&#8211;1542148). The work presented here was generously supported by a research grant from the W.M. Keck Foundation. The authors are also grateful for the support of this work by the Office of Naval Research (via Grant 12368098).

1. Nano-height channel mask preparation
<ol>
	<li>Photolithography: With a pattern describing the desired shape of the nanoheight channels (Figure 1B), use normal photolithography and lift-off procedures to produce nanoheight depressions in an LN wafer. These depressions will become nanoheight channels upon wafer bonding in a later step. 
	NOTE: The lateral dimensions of the nanoscale depressions are microscale in this protocol. Electron beam or He/Ne ion beam lithogr...

<ol>
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Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+thermophoretic+particle+separators:+numerical+analysis+and+simulation.">Novel thermophoretic particle separators: numerical analysis and simulation.</a> Applied Thermal Engineering. 59 (1-2), 527-534 (2013).</li><li>Miansari, M., Friend, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acoustic+Nanofluidics+via+Room-Temperature+Lithium+Niobate+Bonding:+A+Platform+for+Actuation+and+Manipulation+of+Nanoconfined+Fluids+and+Particles.">Acoustic Nanofluidics via Room-Temperature Lithium Niobate Bonding: A Platform for Actuation and Manipulation of Nanoconfined Fluids and Particles.</a> Advanced Functional Materials. 26 (43), 7861-7872 (2016).</li><li>Minzioni, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Roadmap+for+optofluidics.">Roadmap for optofluidics.</a> Journal of Optics. 19 (9), 093003 (2017).</li><li>Connacher, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micro/nano+acoustofluidics:+materials,+phenomena,+design,+devices,+and+applications.">Micro/nano acoustofluidics: materials, phenomena, design, devices, and applications.</a> Lab on a Chip. 18 (14), 1952-1996 (2018).</li><li>Ren, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Etching+characteristics+of+LiNbO3+in+reactive+ion+etching+and+inductively+coupled+plasma.">Etching characteristics of LiNbO3 in reactive ion etching and inductively coupled plasma.</a> Journal of Applied Physics. 103 (3), 034109 (2008).</li><li>Winnall, S., Winderbaum, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lithium+niobate+reactive+ion+etching.">Lithium niobate reactive ion etching.</a> Defence Science and Technology Organization. , (2000).</li><li>Hu, H., Ricken, R., Sohler, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Etching+of+lithium+niobate:+micro-and+nanometer+structures+for+integrated+optics.">Etching of lithium niobate: micro-and nanometer structures for integrated optics.</a> Topical Meeting Photorefractive Materials, Effects, and Devices-Control of Light and Matter, Bad Honnef. , (2009).</li><li>Jackel, J. L., Howard, R. E., Hu, E. L., Lyman, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactive+ion+etching+of+LiNbO3.">Reactive ion etching of LiNbO3.</a> Applied Physics Letters. 38 (11), 907-909 (1981).</li><li>Smith, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Investigation of nanoscale etching and poling of lithium niobate. , (2014).</li><li>Tomita, Y., Sugimoto, M., Eda, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+bonding+of+LiNbO3+single+crystals+for+optical+waveguides.">Direct bonding of LiNbO3 single crystals for optical waveguides.</a> Applied Physics Letters. 66 (12), 1484-1485 (1995).</li><li>Howlader, M. M. R., Suga, T., Kim, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Room+temperature+bonding+of+silicon+and+lithium+niobate.">Room temperature bonding of silicon and lithium niobate.</a> Applied Physics Letters. 89 (3), 031914 (2006).</li><li>Chang, C. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+parametric+study+of+ICP-RIE+etching+on+a+lithium+niobate+substrate.">A parametric study of ICP-RIE etching on a lithium niobate substrate.</a> 10th IEEE International Conference on Nano/Micro Engineered and Molecular Systems. , 485-486 (2015).</li><li>Queste, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deep+reactive+ion+etching+of+quartz,+lithium+niobate+and+lead+titanate.">Deep reactive ion etching of quartz, lithium niobate and lead titanate.</a> JNTE (Journ&#233;es Nationales sur les Technologies) Proceedings. , (2008).</li><li>Xu, J., Wang, C., Tian, Y., Wu, B., Wang, S., Zhang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glass-on-LiNbO3+heterostructure+formed+via+a+two-step+plasma+activated+low-temperature+direct+bonding+method.">Glass-on-LiNbO3 heterostructure formed via a two-step plasma activated low-temperature direct bonding method.</a> Applied Surface Science. 459, 621-629 (2018).</li><li>Tulli, D., Janner, D., Pruneri, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Room+temperature+direct+bonding+of+LiNbO3+crystal+layers+and+its+application+to+high-voltage+optical+sensing.">Room temperature direct bonding of LiNbO3 crystal layers and its application to high-voltage optical sensing.</a> Journal of Micromechanics and Microengineering. 21 (8), 085025 (2011).</li><li>Sridhar, M., Maurya, D. K., Friend, J. R., Yeo, L. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Focused+ion+beam+milling+of+microchannels+in+lithium+niobate.">Focused ion beam milling of microchannels in lithium niobate.</a> Biomicrofluidics. 6 (012819), (2012).</li></ol>

Room-temperature bonding is key to fabricating SAW-integrated nanoslit devices. Five aspects need to be considered to ensure successful bonding and sufficient bonding strength.
Time and power for plasma surface activation 
Increasing the plasma power will help increase the surface energy and accordingly increase the bonding strength. But the downside of increasing the power during plasma surface activation is the increase in surface roughness, which may adversely affect t...

Controllable nanoscale fluid transport in nanochannels&#8212;nanofluidics1&#8212;occurs on the same length scales as most biological macromolecules, and is promising for biological analysis and sensing, medical diagnosis, and material processing. Various designs and simulations have been developed in nanofluidics to manipulate fluids and particle suspensions based on temperature gradients2, Coulomb dragging3, surface waves4, static electric fields5,6,7, and thermophoresis8 over the last fifteen years. Recently, SAW has been shown9 to produce nanoscale fluid pumping and draining with sufficient acoustic pressure to overcome the dominance of surface and viscous forces that otherwise prevent effective fluid transport in nanochannels. The key benefit of acoustic streaming is its ability to drive useful flow in nanostructures without concern over the details of the chemistry of the fluid or particle suspension, making devices that utilize this technique immediately useful in biological analysis, sensing, and other physicochemical applications.
Fabrication of SAW-integrated nanofluidic devices requires fabrication of the electrodes&#8212;the interdigital transducer (IDT)&#8212;on a piezoelectric substrate, lithium niobate10, to facilitate generating the SAW. Reactive ion etching (RIE) is used to form a nanoscale depression in a separate LN piece, and LN-LN bonding of the two pieces produces a useful nanochannel. The fabrication process for SAW devices has been presented in many publications, whether using normal or lift-off ultraviolet photolithography alongside metal sputter or evaporation deposition11. For the LN RIE process to etch a channel in a specific shape, the effects on the etch rate and the channel&#39;s final surface roughness from choosing different LN orientations, mask materials, gas flow, and plasma power have been investigated12,13,14,15,16. Plasma surface activation has been used to significantly increase surface energy and hence improve the strength of bonding in oxides such as LN17,18,19,20. It is likewise possible to heterogeneously bond LN with other oxides, such as SiO2 (glass) via a two-step plasma activated bonding method21. Room-temperature LN-LN bonding, in particular, has been investigated using different cleaning and surface activation treatments22.
Here, we describe in detail the process to fabricate 40 MHz SAW-integrated 100-nm height nanochannels, often called nanoslit channels (Figure 1A). Effective fluid capillary filling and fluid draining by SAW actuation demonstrates the validity of both nanoslit fabrication and SAW performance in such a nanoscale channel. Our approach offers a nano-acoustofluidic system enabling investigation of a variety of physical problems and biological applications.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Absorber</td>
			<td>Dragon Skin, Smooth-On, Inc., Macungie, PA, USA</td>
			<td>Dragon Skin 10 MEDIUM</td>
			<td></td>
		</tr>
		<tr>
			<td>Amplifier</td>
			<td>Mini-Circuits, Brooklyn, NY, USA</td>
			<td>ZHL&#8211;1&#8211;2W&#8211;S+</td>
			<td></td>
		</tr>
		<tr>
			<td>Camera</td>
			<td>Nikon, Minato, Tokyo, Japan</td>
			<td>D5300</td>
			<td></td>
		</tr>
		<tr>
			<td>Developer</td>
			<td>Futurrex, NJ, USA</td>
			<td>RD6</td>
			<td></td>
		</tr>
		<tr>
			<td>Diamond tip engraving pen</td>
			<td>Malco, Memphis, TN, USA</td>
			<td>Malco A50 USA Made Carbide Tipped Scribe</td>
			<td></td>
		</tr>
		<tr>
			<td>Dicing saw</td>
			<td>Disco, Tokyo, Japan</td>
			<td>Disco Automatic Dicing Saw 3220</td>
			<td></td>
		</tr>
		<tr>
			<td>Heating oven</td>
			<td>Carbolite, Hope Valley, UK</td>
			<td>HTCR 6/28</td>
			<td>High Temperature Clean Room Oven - HTCR</td>
		</tr>
		<tr>
			<td>Hole driller</td>
			<td>Dremel, Mount Prospect, Illinois</td>
			<td>Model #4000</td>
			<td>4000 High Performance Variable Speed Rotary</td>
		</tr>
		<tr>
			<td>Inverted microscope</td>
			<td>Amscope, Irvine, CA, USA</td>
			<td>IN480TC-FL-MF603</td>
			<td></td>
		</tr>
		<tr>
			<td>Lithium niobate substrate</td>
			<td>PMOptics, Burlington, MA, USA</td>
			<td>PWLN-431232</td>
			<td>4&#34; double-side polished 0.5 mm thick 128&#176; Y-rotated cut lithium niobate</td>
		</tr>
		<tr>
			<td>Mask aligner</td>
			<td>Heidelberg Instruments, Heidelberg, Germany</td>
			<td>MLA150</td>
			<td></td>
		</tr>
		<tr>
			<td>Nano3 cleanroom facility</td>
			<td>UCSD, La Jolla, CA, USA</td>
			<td></td>
			<td>Fabrication process is performed in it.</td>
		</tr>
		<tr>
			<td>Negative photoresist</td>
			<td>Futurrex, NJ, USA</td>
			<td>NR9-1500PY</td>
			<td></td>
		</tr>
		<tr>
			<td>Oscilloscope</td>
			<td>Keysight Technologies, Santa Rosa, CA, USA</td>
			<td>InfiniiVision 2000 X-Series</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasma surface activation</td>
			<td>PVA TePla, Corona, CA, USA</td>
			<td>PS100</td>
			<td>Tepla Asher</td>
		</tr>
		<tr>
			<td>Polarizer sheet</td>
			<td>Edmund Optics, Barrington, NJ, USA</td>
			<td>#86-182</td>
			<td></td>
		</tr>
		<tr>
			<td>RIE etcher</td>
			<td>Oxford Instruments, Abingdon, UK</td>
			<td>Plasmalab 100</td>
			<td></td>
		</tr>
		<tr>
			<td>Signal generator</td>
			<td>NF Corporation, Yokohama, Japan</td>
			<td>WF1967 multifunction generator</td>
			<td></td>
		</tr>
		<tr>
			<td>Sputter deposition</td>
			<td>Denton Vacuum, NJ, USA</td>
			<td>Denton 18</td>
			<td>Denton Discovery 18 Sputter System</td>
		</tr>
		<tr>
			<td>Teflon wafer dipper</td>
			<td>ShapeMaster, Ogden, IL, USA</td>
			<td>SM4WD1</td>
			<td>Wafer Dipper 4&#34;</td>
		</tr>
	</tbody>
</table>

fabrication of nanoheight channels incorporating surface acoustic wave actuation via lithium niobate for acoustic nanofluidics

Controlled nanoscale manipulation of fluids is known to be exceptionally difficult due to the dominance of surface and viscous forces. Megahertz-order surface acoustic wave (SAW) devices generate tremendous acceleration on their surface, up to 108 m/s2, in turn responsible for many of the observed effects that have come to define acoustofluidics: acoustic streaming and acoustic radiation forces. These effects have been used for particle, cell, and fluid manipulation at the microscale, although more recently SAW has been used to produce similar phenomena at the nanoscale through an entirely different set of mechanisms. Controllable nanoscale fluid manipulation offers a broad range of opportunities in ultrafast fluid pumping and biomacromolecule dynamics useful for physical and biological applications. Here, we demonstrate nanoscale-height channel fabrication via room-temperature lithium niobate (LN) bonding integrated with a SAW device. We describe the entire experimental process including nano-height channel fabrication via dry etching, plasma-activated bonding on lithium niobate, the appropriate optical setup for subsequent imaging, and SAW actuation. We show representative results for fluid capillary filling and fluid draining in a nanoscale channel induced by SAW. This procedure offers a practical protocol for nanoscale channel fabrication and integration with SAW devices useful to build upon for future nanofluidics applications.

We perform fluid capillary filing and SAW-induced fluid draining in nano-height LN slits after successful fabrication and bonding of SAW integrated nanofluidic devices. Surface acoustic waves are generated by IDTs actuated by an amplified sinusoidal signal at the IDTs&#39; resonance frequency of 40 MHz, and the SAW propagates into the nanoslit via a piezoelectric LN substrate. The behavior of the fluid in the nanoslit interacting with SAW may be observed using an inverted microscope.
We demons...

Watch this Scientific Journal Video about Fabrication of Nanoheight Channels Incorporating Surface Acoustic Wave Actuation via Lithium Niobate for Acoustic Nanofluidics at JoVE.com

Fabrication of Nanoheight Channels Incorporating Surface Acoustic Wave Actuation via Lithium Niobate for Acoustic Nanofluidics

We demonstrate fabrication of nanoheight channels with the integration of surface acoustic wave actuation devices upon lithium niobate for acoustic nanofluidics via liftoff photolithography, nano-depth reactive ion etching, and room-temperature plasma surface-activated multilayer bonding of single-crystal lithium niobate, a process similarly useful for bonding lithium niobate to oxides.

Controlled nanoscale manipulation of fluids is known to be exceptionally difficult due to the dominance of surface and viscous forces. Megahertz-order ...

Our protocol provides a detailed fabrication method of nano-height channels incorporating surface acoustic wave actuation via lithium niobate for acoustic nanofluidics. This technique can be used to perform room temperature plasma surface activated multilayer bonding of single crystal lithium niobate, a process equally useful for bonding lithium niobate or silicon dioxide and other oxides. Any debris and particulates should be removed during the cleaning and plasma surface activated processes to prevent bonding failure in the nano-height channel formation.Visual demonstration of this method can capture the entire fabrication process in detail resulting in a clear presentation of the protocol for other researchers. To prepare a nano-height channel mask, place a wafer inscribed with a pattern designed to be a normal photolithography in liftoff procedures into a sputter deposition system and draw down the chamber vacuum to five times 10 to the negative six millitorr. Allow argon to flow at 2.5 millitorr and sputter chromium at 200 watts to produce a 400 nanometer thick sacrificial mask within 18 minutes.At the end of the deposition, completely submerge the wafer in a beaker of acetone and sonicate the wafer at medium intensity for 10 minutes. At the end of the sonication, rinse the wafer with deionized water and dry the wafer with dry nitrogen flow. Then use a dicing saw to divide the wafer into individual chips with one nano-slit pattern per chip.To fabricate the nano-height channel, place the wafer into a reactive ion etching chamber. Set the chamber parameters as indicated to produce a 120 nanometer deep nano-slit in the lithium niobate. To drill the channel inlets and outlets, use double-sided tape to attach a small steel plate to the bottom of a Petri dish and the etched chip to the plate.Fill the dish with water to fully immerse the chip and attach a 0.5 millimeter diameter diamond drill bit to a drill press. Then drill at a speed of at least 10, 000 rotations per minute to machine the desired inlets and outlets. For chromium wet etching, use a diamond tip engraving pen to clearly mark the flat unetched surface of the drilled lithium niobate to keep track of which side the nano-height channel is located and sonicate the chips in chromium etchant.For solvent cleaning of the chips, place chip pairs consisting of one surface acoustic wave device and one etched nanoscale depression chip and immerse the pairs in a beaker of acetone placed with a sonication bath. After two minutes of sonication in acetone, sonicate the chips in methanol for one minute. At the end of the methanol sonication, rinse the chips in deionized water.Next, add hydrogen peroxide to sulfuric acid at a one-to-three ratio in a well-ventilated hood and place all of the chips into a Teflon holder. Carefully place the holder into the beaker of piranha acid for 10 minutes before rinsing the chips and holder in two sequential deionized water baths. After the second rinse, dry the chips with dry nitrogen flow and immediately place the samples into oxygen plasma activation equipment keeping them covered during handling to avoid contamination.Using 120 watts of power while exposing the chips to oxygen flow at 120 standard cubic centimeters for 150 seconds, activate the chip surfaces with the plasma. At the end of the activation, immediately submerge the samples in a fresh deionized water bath for at least two minutes. After drying the chips with dry nitrogen flow, carefully lay the nano-slit chip onto the surface acoustic wave device chip in the desired position with the chips aligned in the appropriate orientation.Then use tweezers or similar to press down upon the sample from its center to initiate the bond, applying gentle pressure to areas that failed to bond after the initial depression. Next, place the bonded samples in a sprung clamp to safely exert loads despite thermal expansion and place the clamped samples into a room temperature oven. Then set the oven temperature to 300 degrees Celsius with a ramp rate of two degrees Celsius per minute maximum with a dwell time of two hours before automatic shutoff.To observe fluid motion in the completed nano-slit, place the nano-slit chip under an inverted microscope and rotate the chip through a linear polarizing filter in the optical path to suitably block birefringence-based image doubling in the lithium niobate. Then add ultrapure deionized water to the inlet and image the fluid progression. For surface acoustic wave actuation, attach absorbers to the ends of the surface acoustic wave device to prevent reflected acoustic waves and set the resonance frequency on a signal generator to around 40 megahertz.Use an amplifier to amplify the signal and use an oscilloscope to measure the actual voltage, current and power applied to the device. Then apply a sinusoidal electrical field to the interdigital transducer and record the fluid motion during the actuation within the nano-slit. In these images, capillary filling of ultrapure deionized water into one 100 nanometer tall 400 micrometer wide channel and one 100 nanometer tall 40 micrometer wide channel is shown.Capillary forces draw fluid filling of the entire nano-slit with a drop of ultrapure water delivered through the inlet and the filling occurred more quickly within the narrower channel due to its larger capillary force. In this experiment, water in a 100 nanometer height slit was drained to show a water-air interface with the maximum length at the middle indicating a maximum acoustic energy at the middle of the surface acoustic wave device. A threshold applied power of around one watt is required to force the acoustic pressure to be larger than the capillary pressure to drive a visible draining phenomenon.Most fabrication processes should be conducted in a clean room to prevent microscale particulate contamination and fluid used for filling should be ultrapure to prevent clogging of the nano-slit. Our approach offers a nano-acoustic fluidics system for the investigation of a variety of physical problems and biological applications at the nanoscale.

fabrication-nanoheight-channels-incorporating-surface-acoustic-wave

Research

JoVE Journal

Engineering

Construction and Testing of Coin Cells of Lithium Ion Batteries

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime. Lithium ion batteries have also been considered to be used in electric and hybrid vehicles1 or even electrical grid stabilization systems2. All these applications simulate a dramatic increase in the research and development of battery materials3-7, including new materials3,8, doping9, nanostructuring10-13, coatings or surface modifications14-17 and novel binders18. Consequently, an increasing number of physicists, chemists and materials scientists have recently ventured into this area. Coin cells are widely used in research laboratories to test new battery materials; even for the research and development that target large-scale and high-power applications, small coin cells are often used to test the capacities and rate capabilities of new materials in the initial stage. 
 In 2010, we started a National Science Foundation (NSF) sponsored research project to investigate the surface adsorption and disordering in battery materials (grant no. DMR-1006515). In the initial stage of this project, we have struggled to learn the techniques of assembling and testing coin cells, which cannot be achieved without numerous help of other researchers in other universities (through frequent calls, email exchanges and two site visits). Thus, we feel that it is beneficial to document, by both text and video, a protocol of assembling and testing a coin cell, which will help other new researchers in this field. This effort represents the "Broader Impact" activities of our NSF project, and it will also help to educate and inspire students.
In this video article, we document a protocol to assemble a CR2032 coin cell with a LiCoO2 working electrode, a Li counter electrode, and (the mostly commonly used) polyvinylidene fluoride (PVDF) binder. To ensure new learners to readily repeat the protocol, we keep the protocol as specific and explicit as we can. However, it is important to note that in specific research and development work, many parameters adopted here can be varied. First, one can make coin cells of different sizes and test the working electrode against a counter electrode other than Li. Second, the amounts of C black and binder added into the working electrodes are often varied to suit the particular purpose of research; for example, large amounts of C black or even inert powder were added to the working electrode to test the "intrinsic" performance of cathode materials14. Third, better binders (other than PVDF) have also developed and used18. Finally, other types of electrolytes (instead of LiPF6) can also be used; in fact, certain high-voltage electrode materials will require the uses of special electrolytes7.

A protocol to construct and test coin cells of lithium ion batteries is described. The specific procedures of making a working electrode, preparing a counter electrode, assembling a cell inside a glovebox and testing the cell are presented.

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime.  Lithium ion ...

Synthesis of Phase-shift Nanoemulsions with Narrow Size Distributions for Acoustic Droplet Vaporization and Bubble-enhanced Ultrasound-mediated Ablation

High-intensity focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To enhance localized heating and improve thermal ablation in tumors, lipid-coated perfluorocarbon droplets have been developed which can be vaporized by HIFU. The vasculature in many tumors is abnormally leaky due to their rapid growth, and nanoparticles are able to penetrate the fenestrations and passively accumulate within tumors. Thus, controlling the size of the droplets can result in better accumulation within tumors. In this report, the preparation of stable droplets in a phase-shift nanoemulsion (PSNE) with a narrow size distribution is described. PSNE were synthesized by sonicating a lipid solution in the presence of liquid perfluorocarbon. A narrow size distribution was obtained by extruding the PSNE multiple times using filters with pore sizes of 100 or 200 nm. The size distribution was measured over a 7-day period using dynamic light scattering. Polyacrylamide hydrogels containing PSNE were prepared for in vitro experiments. PSNE droplets in the hydrogels were vaporized with ultrasound and the resulting bubbles enhanced localized heating. Vaporized PSNE enables more rapid heating and also reduces the ultrasound intensity needed for thermal ablation. Thus, PSNE is expected to enhance thermal ablation in tumors, potentially improving therapeutic outcomes of HIFU-mediated thermal ablation treatments.

Phase-shift nanoemulsions (PSNE) can be vaporized using high intensity focused ultrasound to enhance localized heating and improve thermal ablation in tumors. In this report, the preparation of stable PSNE with a narrow size distribution is described. Furthermore, the impact of vaporized PSNE on ultrasound-mediated ablation is demonstrated in tissue-mimicking phantoms.

High-intensity  focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To  enhance localized heating and improve thermal ablation in ...

Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we present the fabrication protocol for a multilayered SAW acoustic counterflow device. The device is fabricated starting from a lithium niobate (LN) substrate onto which two interdigital transducers (IDTs) and appropriate markers are patterned. A polydimethylsiloxane (PDMS) channel cast on an SU8 master mold is finally bonded on the patterned substrate. Following the fabrication procedure, we show the techniques that allow the characterization and operation of the acoustic counterflow device in order to pump fluids through the PDMS channel grid. We finally present the procedure to visualize liquid flow in the channels. The protocol is used to show on-chip fluid pumping under different flow regimes such as laminar flow and more complicated dynamics characterized by vortices and particle accumulation domains.

In this video we first describe fabrication and operation procedures of a surface acoustic wave (SAW) acoustic counterflow device. We then demonstrate an experimental setup that allows for both qualitative flow visualization and quantitative analysis of complex flows within the SAW pumping device.

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we ...

Fabrication of Uniform Nanoscale Cavities via Silicon Direct Wafer Bonding

Measurements of the heat capacity and superfluid fraction of confined 4He have been performed near the lambda transition using lithographically patterned and bonded silicon wafers. Unlike confinements in porous materials often used for these types of experiments3, bonded wafers provide predesigned uniform spaces for confinement. The geometry of each cell is well known, which removes a large source of ambiguity in the interpretation of data.
Exceptionally flat, 5 cm diameter, 375 &#181;m thick Si wafers with about 1 &#181;m variation over the entire wafer can be obtained commercially (from Semiconductor Processing Company, for example). Thermal oxide is grown on the wafers to define the confinement dimension in the z-direction. A pattern is then etched in the oxide using lithographic techniques so as to create a desired enclosure upon bonding. A hole is drilled in one of the wafers (the top) to allow for the introduction of the liquid to be measured. The wafers are cleaned2 in RCA solutions and then put in a microclean chamber where they are rinsed with deionized water4. The wafers are bonded at RT and then annealed at ~1,100 &#176;C. This forms a strong and permanent bond. This process can be used to make uniform enclosures for measuring thermal and hydrodynamic properties of confined liquids from the nanometer to the micrometer scale.

A method for permanently bonding two silicon wafers so as to realize a uniform enclosure is described. This includes wafer preparation, cleaning, RT bonding, and annealing processes. The resulting bonded wafers (cells) have uniformity of enclosure ~1%1,2. The resulting geometry allows for measurements of confined liquids and gasses.

Measurements of the heat capacity and superfluid fraction of confined 4He have been performed near the lambda transition using lithographically patterned ...

Patterning via Optical Saturable Transitions - Fabrication and Characterization

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical Saturable Transitions (POST). In this technique the chemical properties of organic photochromic molecules that undergo single-photon reactions are exploited, enabling rapid top-down nanopatterning over large areas at low light intensities, thereby, allowing for the circumvention of the far-field diffraction barrier.4 Simple, cost-effective, high throughput and resolution alternatives to nanopatterning are being explored, such as, two-photon polymerization5,6, beam pen lithography (BPL)7, scanning electron beam lithography (SEBL), and focused ion beam (FIB) patterning. However, multi-photon approaches require high light intensities, which limit their potential for high throughput and offer low image contrast. Although, electron and ion beam lithographic processes offer increased resolution, the serial nature of the process is limited to slow writing speeds, which also prevents patterning of features over large areas. Beam-pen lithography is an approach towards parallel near-field optical lithography. However, the gap between the source of the beam and the surface of the photoresist needs to be controlled extremely precisely for good pattern uniformity and this is very challenging to accomplish for large arrays of beams. Patterning via Optical Saturable Transitions (POST) is an alternative optical nanopatterning technique for patterning sub-wavelength features1-3. Since this technique uses single photons instead of electrons, it is extremely fast and does not require high light intensities1-3, opening the door to massive parallelization.

We report that the diffraction limit of conventional optical lithography can be overcome by exploiting the transitions of organic photochromic derivatives induced by their photoisomerization at low light intensities.1-3 This paper outlines our fabrication technique and two locking mechanisms, namely: dissolution of one photoisomer and electrochemical oxidation.

This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical ...

Characterization of Full Set Material Constants and Their Temperature Dependence for Piezoelectric Materials Using Resonant Ultrasound Spectroscopy

During the operation of high power electromechanical devices, a temperature rise is unavoidable due to mechanical and electrical losses, causing the degradation of device performance. In order to evaluate such degradations using computer simulations, full matrix material properties at elevated temperatures are needed as inputs. It is extremely difficult to measure such data for ferroelectric materials due to their strong anisotropic nature and property variation among samples of different geometries. Because the degree of depolarization is boundary condition dependent, data obtained by the IEEE (Institute of Electrical and Electronics Engineers) impedance resonance technique, which requires several samples with drastically different geometries, usually lack self-consistency. The resonant ultrasound spectroscopy (RUS) technique allows the full set material constants to be measured using only one sample, which can eliminate errors caused by sample to sample variation. A detailed RUS procedure is demonstrated here using a lead zirconate titanate (PZT-4) piezoceramic sample. In the example, the complete set of material constants was measured from room temperature to 120 &#176;C. Measured free dielectric constants <img alt="Equation 1" src="/files/ftp_upload/53461/image001.jpg" /> and&#160;<img alt="Equation 2" src="/files/ftp_upload/53461/image002.jpg" /> were compared with calculated ones based on the measured full set data, and piezoelectric constants d15 and d33 were also calculated using different formulas. Excellent agreement was found in the entire range of temperatures, which confirmed the self-consistency of the data set obtained by the RUS.

This protocol describes the procedure of measuring the temperature dependence of the full set material constants of piezoelectric materials using resonant ultrasound spectroscopy (RUS).

During the operation of high power electromechanical devices, a temperature rise is unavoidable due to mechanical and electrical losses, causing the ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. 
Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties.
The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.

Development of new ablative materials and their numerical modeling requires extensive experimental investigation. This protocol describes procedures for material response characterization in plasma flows with the core techniques being non-intrusive methods to track the material recession along with the chemistry in the reactive boundary layer by emission spectroscopy.

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution ...

Free-form Light Actuators &#8212; Fabrication and Control of Actuation in Microscopic Scale

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted researchers&#39; attention in many fields. Most of the studies focused on macroscopic LCE structures (films, fibers) and their miniaturization is still in its infancy. Recently developed lithography techniques, e.g., mask exposure and replica molding, only allow for creating 2D structures on LCE thin films. Direct laser writing (DLW) opens access to truly 3D fabrication in the microscopic scale. However, controlling the actuation topology and dynamics at the same length scale remains a challenge.
In this paper we report on a method to control the liquid crystal (LC) molecular alignment in the LCE microstructures of arbitrary three-dimensional shape. This was made possible by a combination of direct laser writing for both the LCE structures as well as for micrograting patterns inducing local LC alignment. Several types of grating patterns were used to introduce different LC alignments, which can be subsequently patterned into the LCE structures. This protocol allows one to obtain LCE microstructures with engineered alignments able to perform multiple opto-mechanical actuation, thus being capable of multiple functionalities. Applications can be foreseen in the fields of tunable photonics, micro-robotics, lab-on-chip technology and others.

Free-form Light Actuators &amp;#8212; Fabrication and Control of Actuation in Microscopic Scale

Here, we fabricate 3D polymeric micro/nano structures in which both the shape and the molecular alignment can be engineered with nanometer scale accuracy by the use of direct laser writing. Light induced deformation of several types of liquid crystalline elastomer microstructures can be controlled in the microscopic scale.

Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted ...

Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must be smaller than the incident wavelength of sound and the width of the fluidic channels are typically tens to hundreds of micrometers across, acoustofluidic devices typically use ultrasonic waves generated from a piezoelectric transducer pulsating at high frequencies (in the megahertz range). At characteristic frequencies that depend on the geometry of the device, it is possible to induce the formation of standing waves that can focus particles along desired fluidic streamlines within a bulk flow. Here, we describe a method for the fabrication of acoustophoretic devices from common materials and clean room equipment. We show representative results for the focusing of particles with positive or negative acoustic contrast factors, which move towards the pressure nodes or antinodes of the standing waves, respectively. These devices offer enormous practical utility for precisely positioning large numbers of microscopic entities (e.g., cells) in stationary or flowing fluids for applications ranging from cytometry to assembly.

Acoustofluidic devices use ultrasonic waves within microfluidic channels to manipulate, concentrate and isolate suspended micro and nanoscopic entities. This protocol describes the fabrication and operation of such a device supporting bulk acoustic standing waves to focus particles in a central streamline without the aid of sheath fluids.

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must ...

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of lithium-ion (Li-ion) batteries. However, a number of setbacks prevent their integration into commercial devices. The main limiting factor is due to nanoscale phenomena occurring at the electrode/electrolyte interfaces, ultimately leading to degradation of battery operation. These key problems are highly challenging to observe and characterize as these batteries contain multiple buried interfaces. One approach for direct observation of interfacial phenomena in thin film batteries is through the fabrication of electrochemically active nanobatteries by a focused ion beam (FIB). As such, a reliable technique to fabricate nanobatteries was developed and demonstrated in recent work. Herein, a detailed protocol with a step-by-step process is presented to enable the reproduction of this nanobattery fabrication process. In particular, this technique was applied to a thin film battery consisting of LiCoO2/LiPON/a-Si, and has further been previously demonstrated by in situ cycling within a transmission electron microscope.

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

A protocol for the fabrication of electrochemically active LiPON-based solid-state lithium-ion nanobatteries using a focused ion beam is presented.

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of ...