Name: evaluating targeting accuracy in the focal plane for an ultrasound-guided high-intensity focused ultrasound phased-array system
Uploaded: 2019-03-06T14:45:00
Description: Watch this Scientific Journal Video about Evaluating Targeting Accuracy in the Focal Plane for an Ultrasound-guided High-intensity Focused Ultrasound Phased-array System at JoVE.com

This work has been supported in part by the National Natural Science Foundation of China (81402522), the Shanghai Key Technology R&#38;D Program (17441907400) from the Science and Technology Commission of Shanghai Municipality, and Shanghai Jiao Tong University Medical Engineering Research Fund (YG2017QN40, YG2015ZD10). Zhonghui Medical Technology (Shanghai) Co., Ltd. is also acknowledged for providing the USgHIFU system. The authors thank Wenzhen Zhu and Junhui Dong for the phantom preparation and their assistance in the experiments.

1. Marker design and fabrication
<ol>
	<li>Design a square model using computer-aided design software. Set each side as sticks with lengths of 40 mm and thicknesses of 2 mm. Place a solid ball with a 10 mm diameter at each corner of the square model.</li>
	<li>Use acrylonitrile butadiene styrene photosensitive resin as the material for printing.</li>
	<li>Send the 3D model file to a manufacturer for fabrication.</li>
</ol>
2. Phantom preparation
<ol>
	<li>Attach a plastic cylinder (with a diam...

<ol>
	<li>Wang, S. B., He, C. C., Li, K., Ji, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+of+a+112-channel+phased-array+ultrasonography-guided+focused+ultrasound+system+in+combination+with+switch+of+ultrasound+imaging+plane+for+tissue+ablation.">Design of a 112-channel phased-array ultrasonography-guided focused ultrasound system in combination with switch of ultrasound imaging plane for tissue ablation.</a> 2014 Symposium on Piezoelectricity, Acoustic Waves, and Device Applications (SPAWDA). , 134-137 (2014).</li><li>Choi, J. 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F., Chen, Y. Z., Ji, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+calibration+of+targeting+errors+for+an+ultrasound-guided+high-intensity+focused+ultrasound+system.">The calibration of targeting errors for an ultrasound-guided high-intensity focused ultrasound system.</a> 2017 IEEE International Symposium on Medical Measurements and Applications (MeMeA). , 10-14 (2017).</li><li>Ellens, N. P. K., 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=The+targeting+accuracy+of+a+preclinical+MRI-guided+focused+ultrasound+system.">The targeting accuracy of a preclinical MRI-guided focused ultrasound system.</a> Medical Physics. 42 (1), 430-439 (2015).</li><li>McDannold, N., Hynynen, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quality+assurance+and+system+stability+of+a+clinical+MRI-guided+focused+ultrasound+system:+Four-year+experience.">Quality assurance and system stability of a clinical MRI-guided focused ultrasound system: Four-year experience.</a> Medical Physics. 33 (11), 4307-4313 (2006).</li><li>Gorny, K. R., 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=MR+guided+focused+ultrasound:+technical+acceptance+measures+for+a+clinical+system.">MR guided focused ultrasound: technical acceptance measures for a clinical system.</a> Physics in Medicine and Biology. 51 (12), 3155-3173 (2006).</li><li>Kim, Y. 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=MR+thermometry+analysis+of+sonication+accuracy+and+safety+margin+of+volumetric+MR+imaging-guided+high-intensity+focused+ultrasound+ablation+of+symptomatic+uterine+fibroids.">MR thermometry analysis of sonication accuracy and safety margin of volumetric MR imaging-guided high-intensity focused ultrasound ablation of symptomatic uterine fibroids.</a> Radiology. 265 (2), 627-637 (2012).</li><li>Chauhan, S., ter Haar, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FUSBOTUS:+empirical+studies+using+a+surgical+robotic+system+for+urological+applications.">FUSBOTUS: empirical studies using a surgical robotic system for urological applications.</a> AIP Conference Proceedings. 911, 117-121 (2007).</li><li>An, C. Y., Syu, J. H., Tseng, C. S., Chang, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+ultrasound+imaging-guided+robotic+HIFU+ablation+experimental+system+and+accuracy+evaluations.">An ultrasound imaging-guided robotic HIFU ablation experimental system and accuracy evaluations.</a> Applied Bionics and Biomechanics. 2017, 5868695 (2017).</li><li>Li, D. H., Shen, G. F., Bai, J. F., Chen, Y. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Focus+shift+and+phase+correction+in+soft+tissues+during+focused+ultrasound+surgery.">Focus shift and phase correction in soft tissues during focused ultrasound surgery.</a> IEEE Transactions on Biomedical Engineering. 58 (6), 1621-1628 (2011).</li><li>N'Djin, W. A., 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=Utility+of+a+tumor-mimic+model+for+the+evaluation+of+the+accuracy+of+HIFU+treatments.+results+of+in+vitro+experiments+in+the+liver.">Utility of a tumor-mimic model for the evaluation of the accuracy of HIFU treatments. results of in vitro experiments in the liver.</a> Ultrasound in Medicine and Biology. 34 (12), 1934-1943 (2008).</li><li>Tang, T. H., 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+new+method+for+absolute+accuracy+evaluation+of+a+US-guided+HIFU+system+with+heterogeneous+phantom.">A new method for absolute accuracy evaluation of a US-guided HIFU system with heterogeneous phantom.</a> 2016 IEEE International Ultrasonics Symposium (IUS). , 1-4 (2016).</li><li>Li, K., Bai, J. F., Chen, Y. 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Robotic components have been used for extracorporeal USgHIFU systems. To evaluate the targeting accuracy of such systems, reference markers11,12,18, in vitro tissue17, tumor-mimic models, and temperature-sensitive phantoms have been used alone or in combination10,20. Compared with the protocols in those studies, this method is more clinically rele...

The phased array is increasingly designed and equipped in HIFU systems1,2,3,4,5,6,7. In USgHIFU phased-array systems, a US imaging probe is usually mounted in the central hole of the spherical HIFU transducer1,2,8. The probe is rotatable for targeting and image reconstruction in the three-dimensional space9. Precise targeting is required for the safety and efficacy of HIFU treatment. However, most of the studies for the evaluation of targeting accuracy have been performed for magnetic resonance-guided HIFU systems or USgHIFU systems configured with a self-focused HIFU transducer10,11,12,13,14,15,16. The purpose of the method described below is to evaluate the targeting accuracy in the focal plane for USgHIFU phased array systems.
A bovine muscle/marker-embedded phantom along the clinically relevant beam path is used in the evaluation of the targeting accuracy of a clinical USgHIFU phased-array system. A square model with four balls at the corners is fabricated and embedded, in combination with bovine muscle, into the transparent phantom. A regular hexagon is selected as the target based on the positions of the centers of four balls identified in the reconstructed US image on the treatment plane. After HIFU sonications, the treatment plane of the phantom is scanned, and the boundary of the lesion, as well as the positions of the four balls, can be determined in the scanned image. The targeting accuracy can be evaluated by measuring the distance between the centers of target and lesion, as well as three derivative parameters.
The method is simpler than the measurement of the targeting error using robotic movement with a specific reference object11,17,18 and more clinically relevant in comparison to the method based on single focal spot ablation in a homogeneous phantom10. This method can be used in the evaluation of the targeting accuracy of USgHIFU phased array systems. It can be also used for other USgHIFU systems equipped with self-focused HIFU transducers.

<table border="0" cellpadding="0" cellspacing="0" style="width:849px;" width="849">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:233px;">Acrylamide</td>
			<td style="width:276px;">Amresco</td>
			<td style="width:160px;">D403-2</td>
			<td style="width:180px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acrylic baseboard</td>
			<td>LAO NIAO STORES</td>
			<td>customized</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acrylic cylindrical water tank&#160;</td>
			<td>LAO NIAO STORES</td>
			<td>customized</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ammonium persulfate</td>
			<td>Yatai United Chemical Co., Ltd (Wuxi, China)</td>
			<td>2017-03-01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Beaker</td>
			<td>East China Chemical Reagent Instrument Store</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bis-acrylamide</td>
			<td>Amresco</td>
			<td>M0172</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bovine muscle</td>
			<td>Market</td>
			<td style="width:160px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Chopping board</td>
			<td>JIACHI</td>
			<td dir="LTR">JC-ZB40</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cylindrical plastic&#160;phantom holder</td>
			<td>QIYINPAI</td>
			<td>customized</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Degassed deionized water</td>
			<td style="width:276px;"></td>
			<td style="width:160px;"></td>
			<td>made by the USgHIFU system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Electric balance</td>
			<td>YINGHENG</td>
			<td>11119453359</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glass rod</td>
			<td>East China Chemical Reagent Instrument Store</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Knife</td>
			<td>SHIBAZI</td>
			<td dir="LTR">SL1210-C</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mask</td>
			<td>Medicom</td>
			<td>2498</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">N,N,N&#8217;,N&#8217;&#8211;Tetramethylethylenediamine</td>
			<td>Zhanyun Chemical Co., Ltd (Shanghai, China)</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Rubber glove</td>
			<td>AMMEX</td>
			<td>YZB/MAL 0587-2018</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Scanner</td>
			<td>Fuji Xerox</td>
			<td>DocuPrint M268dw</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Screwdriver</td>
			<td>Stanley</td>
			<td>T6</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Silica gel</td>
			<td>GE</td>
			<td>381</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Square model</td>
			<td>QIYINPAI</td>
			<td>customized</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Stainless steel spoons</td>
			<td>East China Chemical Reagent Instrument Store</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sucker</td>
			<td>East China Chemical Reagent Instrument Store</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Swine muscle</td>
			<td>Market</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">USgHIFU system</td>
			<td>Zhonghui Medical Technology (Shanghai) Co., Ltd.</td>
			<td>SUA-I</td>
			<td></td>
		</tr>
	</tbody>
</table>

evaluating targeting accuracy in the focal plane for an ultrasound-guided high-intensity focused ultrasound phased-array system

Phased arrays are increasingly used as high-intensity focused ultrasound (HIFU) transducers in the existing extracorporeal ultrasound-guided HIFU (USgHIFU) systems. The HIFU transducers in such systems are usually spherical in shape with a central hole where a US imaging probe is mounted and can be rotated. The image on the plane of treatment can be reconstructed through the image sequence acquired during the rotation of the probe. Therefore, the treatment plan can be made on the reconstructed images. In order to evaluate the targeting accuracy in the focal plane of such systems, the protocol of a method using a bovine muscle and marker-embedded phantom is described. In the phantom, four solid balls at the corners of a square resin model serve as the reference markers in the reconstructed image. The target should be moved so that both its center and the center of the square model can coincide according to their relative positions in the reconstructed image. Swine muscle with a thickness of about 30 mm is placed above the phantom to mimic the beam path in clinical settings. After sonication, the treatment plane in the phantom is scanned and the boundary of the associated lesion is extracted from the scanned image. The targeting accuracy can be evaluated by measuring the distance between the centers of target and lesion, as well as three derivative parameters. This method cannot only evaluate the targeting accuracy of the target consisting of multiple focal spots rather than a single focal spot in a clinically relevant beam path of the USgHIFU phased-array system, but it can be also used in the preclinical evaluation or regular maintenance of USgHIFU systems configured with phased-array or self-focused HIFU transducer.

We made phantoms dedicated to evaluating the targeting accuracy of a clinical USgHIFU phased-array system with the targets of three different sizes. Figure 1 displays the US image at angles of 0&#176; and 90&#176;. The interfaces are clear, and the sticks of the square model are bright in the US images. Figure 2 demonstrates the reconstructed US image in the treatment plane and the focal spots of the largest target. The centers o...

Watch this Scientific Journal Video about Evaluating Targeting Accuracy in the Focal Plane for an Ultrasound-guided High-intensity Focused Ultrasound Phased-array System at JoVE.com

Evaluating Targeting Accuracy in the Focal Plane for an Ultrasound-guided High-intensity Focused Ultrasound Phased-array System

This study describes a protocol to evaluate the targeting accuracy in the focal plane of an ultrasound-guided high-intensity focused ultrasound phased-array system.

Phased arrays are increasingly used as high-intensity focused ultrasound (HIFU) transducers in the existing extracorporeal ultrasound-guided HIFU ...

Accurate targeting is essential to ensure safety and efficacy for image-guided, high-intensity focused ultrasound systems. Our protocol can evaluate in targeting accuracy of ultrasound-guided, high-intensity focused ultrasound phase-array systems. This technique can be used to evaluate the targeting accuracy in the treatment plane while taking into consideration the clinically relevant tissue paths.This method can be applied to ultrasound-guided, high-intensity focused ultrasound systems with a self-focused transducer using different ultrasound image reconstruction methods. Visual demonstration of this method can help others fully understand the protocol, especially how to determine the location of the target in the reconstructed ultrasound image. Before making the phantom, fabricate the model.This 3D-printed model is a square with side lengths of 40 millimeters. A solid ball is at each corner. With the model at hand, make the phantom holder.For this, get an acrylic baseboard and an eight-centimeter-diameter plastic cylinder that is three centimeters tall. Use silica gel to attach them to form a holder. Let the assembly sit for one hour.Now, move on to make the phantom from fresh bovine muscle. Slice the muscle into a square with sides of 30 millimeters and 10-millimeter thickness. Ventilate the tissue with a fan for two hours to evaporate moisture.Next, prepare to work with hazardous chemicals. Pour degassed and deionized water into a beaker. Add acrylamide, and stir until it is dissolved.Then, add bis-acrylamide, and stir until dissolved. Finally, add tetramethylethylenediamine, and stir until the solution is uniform. This is solution one.In another beaker with degassed and deionized water, add ammonium persulfate, and stir to dissolve. This is solution two. When the phantom has solidified, retrieve the 3D-printed model, and place it on the phantom surface.With the model in place, the next step is to put the sliced bovine muscle in the middle of the model. Pour the rest of solution one into the phantom holder. Move the bovine muscle to remove air at the interface of the phantom and the slice.Continue by pouring the remainder of the solution two into the phantom holder. Then, stir for five seconds. Adjust the location of the muscle to be at the center of the phantom, and let everything sit for 20 minutes to solidify.Once it has solidified, use a screwdriver to remove the silica gel, holding the cylinder and base together, and slowly detach the two. Start the ultrasound-guided, high-intensity focused ultrasound system. Turn on the water-processing module, and set the circulation speed.To continue, have a cylindrical tank filled with degassed water at room temperature. The tank diameter is 30 centimeters, and its height is 13 centimeters. Get the phantom holder, and place it in the degassed water.Take measures to ensure the holder is fixed tightly in place. Next, move the treatment bed and the therapeutic unit to allow imaging the phantom. The balloon of the therapeutic unit should be immersed in the degassed water.Be prepared with a sample of swine muscle before continuing. The sample should be about 100 millimeters long and be about 30 millimeters thick. Put the sample aside, and slowly move the therapeutic unit up and down.The goal is to make sure the treatment plane is at the upper interface of the sliced bovine muscle and phantom. With the ultrasound imaging probe at zero degrees, move the water tank to make the imaging axis pass through the middle of the two parallel lines in the image. Next, rotate the imaging probe to 90 degrees.Then, move the tank to make the axis pass through the middle of the two parallel lines in the image. Reconstruct the ultrasound image in the treatment plane at the depth of geometric focus. Check that the four balls are clearly shown in the reconstructed image.Also, check if the target is located at the center of the square model. When ready, lift the therapeutic unit in order to place the swine muscle above the phantom. Here, the swine muscle is in position and ready for the next steps.Move the therapeutic unit back into position for imaging. Arrange the depth of geometric focus to be three millimeters beneath the upper surface of the bovine muscle. Continue by setting the parameters for high-intensity focused ultrasound sonication, including the pulse duration and power, among others.Set the exposure time for the chosen hexagonal virtual target and a two-second exposure time for the focal spot at the geometric center of the phase array. Start the sonication, and put a foot on the foot pedal of the sonication instrument. During sonication, observe and record the ultrasound image to allow comparison of the echogenicity of different samples.Remove the phantom before using similarly prepared phantoms to repeat the sonication steps with the other virtual targets. This is an ultrasound image at an angle of zero degrees. An ultrasound image at an angle of 90 degrees is similar.Both images show clear interfaces between the swine muscle, phantom, and bovine muscle. In addition, the sticks of the square model are bright. This is the reconstructed image in the treatment plane.The blue circles encompass the highest average gray value in the red squares and identify the positions of the four balls in the model. The blue circles also determine the center of the square model, which is the center of the targets. The brown squares indicate the focal spots in the largest regular hexagonal target.Determining the location of the four balls in the reconstructed ultrasound image is important for matching the target center with the model center. The chemical materials used for phantom preparation are slightly hazardous. A mask and gloves should be worn during the procedure.

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Engineering

Evaluating Plasmonic Transport in Current-carrying Silver Nanowires

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information support1,2,3. In this context, metal nanowires are especially desirable for realizing dense routing networks4. A prerequisite to operate such shared nanowire-based platform relies on our ability to electrically contact individual metal nanowires and efficiently excite surface plasmon polaritons5 in this information support. In this article, we describe a protocol to bring electrical terminals to chemically-synthesized silver nanowires6 randomly distributed on a glass substrate7. The positions of the nanowire ends with respect to predefined landmarks are precisely located using standard optical transmission microscopy before encapsulation in an electron-sensitive resist. Trenches representing the electrode layout are subsequently designed by electron-beam lithography. Metal electrodes are then fabricated by thermally evaporating a Cr/Au layer followed by a chemical lift-off. The contacted silver nanowires are finally transferred to a leakage radiation microscope for surface plasmon excitation and characterization8,9. Surface plasmons are launched in the nanowires by focusing a near infrared laser beam on a diffraction-limited spot overlapping one nanowire extremity5,9. For sufficiently large nanowires, the surface plasmon mode leaks into the glass substrate9,10. This leakage radiation is readily detected, imaged, and analyzed in the different conjugate planes in leakage radiation microscopy9,11. The electrical terminals do not affect the plasmon propagation. However, a current-induced morphological deterioration of the nanowire drastically degrades the flow of surface plasmons. The combination of surface plasmon leakage radiation microscopy with a simultaneous analysis of the nanowire electrical transport characteristics reveals the intrinsic limitations of such plasmonic circuitry.

Silver nanowires can simultaneously transport electrons and optical information in the form of surface plasmons. A procedure is described here to realize such a shared circuitry and the limitations at propagating both information carriers are evaluated.

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information ...

Measuring Material Microstructure Under Flow Using 1-2 Plane Flow-Small Angle Neutron Scattering

A new small-angle neutron scattering (SANS) sample environment optimized for studying the microstructure of complex fluids under simple shear flow is presented. The SANS shear cell consists of a concentric cylinder Couette geometry that is sealed and rotating about a horizontal axis so that the vorticity direction of the flow field is aligned with the neutron beam enabling scattering from the 1-2 plane of shear (velocity-velocity gradient, respectively). This approach is an advance over previous shear cell sample environments as there is a strong coupling between the bulk rheology and microstructural features in the 1-2 plane of shear. Flow-instabilities, such as shear banding, can also be studied by spatially resolved measurements. This is accomplished in this sample environment by using a narrow aperture for the neutron beam and scanning along the velocity gradient direction. Time resolved experiments, such as flow start-ups and large amplitude oscillatory shear flow are also possible by synchronization of the shear motion and time-resolved detection of scattered neutrons. Representative results using the methods outlined here demonstrate the useful nature of spatial resolution for measuring the microstructure of a wormlike micelle solution that exhibits shear banding, a phenomenon that can only be investigated by resolving the structure along the velocity gradient direction. Finally, potential improvements to the current design are discussed along with suggestions for supplementary experiments as motivation for future experiments on a broad range of complex fluids in a variety of shear motions.

A shear cell is developed for small-angle neutron scattering measurements in the velocity-velocity gradient plane of shear and is used to characterize complex fluids. Spatially resolved measurements in the velocity gradient direction are possible for studying shear-banding materials. Applications include investigations of colloidal dispersions, polymer solutions, and self-assembled structures.

A new small-angle neutron scattering (SANS) sample environment optimized for studying the microstructure of complex fluids under simple shear flow is ...

Laboratory Drop Towers for the Experimental Simulation of Dust-aggregate Collisions in the Early Solar System

For the purpose of investigating the evolution of dust aggregates in the early Solar System, we developed two vacuum drop towers in which fragile dust aggregates with sizes up to ~10 cm and porosities up to 70% can be collided. One of the drop towers is primarily used for very low impact speeds down to below 0.01 m/sec and makes use of a double release mechanism. Collisions are recorded in stereo-view by two high-speed cameras, which fall along the glass vacuum tube in the center-of-mass frame of the two dust aggregates. The other free-fall tower makes use of an electromagnetic accelerator that is capable of gently accelerating dust aggregates to up to 5 m/sec. In combination with the release of another dust aggregate to free fall, collision speeds up to ~10 m/sec can be achieved. Here, two fixed high-speed cameras record the collision events. In both drop towers, the dust aggregates are in free fall during the collision so that they are weightless and match the conditions in the early Solar System.

We present a technique to achieve low-velocity to intermediate-velocity collisions between fragile dust aggregates in the laboratory. For this purpose, two vacuum drop-tower setups have been developed that allow collision velocities between &#60;0.01 and ~10 m/sec. The collision events are recorded by high-speed imaging.

For the purpose of investigating the evolution of dust aggregates in the early Solar System, we developed two vacuum drop towers in which fragile dust ...

Ambient Method for the Production of an Ionically Gated Carbon Nanotube Common Cathode in Tandem Organic Solar Cells

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two solution-processed polymeric cells connected in parallel by a transparent carbon nanotubes (CNT) interlayer. This structure includes improvements in fabrication techniques for tandem OPV devices. First the need for ambient-processed cathodes is considered. The CNT anode in the tandem device is tuned via ionic gating to become a common cathode. Ionic gating employs electric double layer charging to lower the work function of the CNT electrode. Secondly, the difficulty of sequentially stacking tandem layers by solution-processing is addressed. The devices are fabricated via solution and dry-lamination in ambient conditions with parallel processing steps. The method of fabricating the individual polymeric cells, the steps needed to laminate them together with a common CNT cathode, and then provide some representative results are described. These results demonstrate ionic gating of the CNT electrode to create a common cathode and addition of current and efficiency as a result of the lamination procedure.

A method of fabricating, in ambient conditions, organic photovoltaic tandem devices in a parallel configuration is presented. These devices feature an air-processed, semi-transparent, carbon nanotube common cathode.

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two ...

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal&#8211;semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 &#937;&#8722;1 cm&#8722;1, with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed. Similar results can be obtained for other layer semiconductor materials such as MoS2 and WS2.

We describe the approaches for the device fabrication and electrical characterization of molybdenum diselenide (MoSe2) layer semiconductor nanostructures with different thicknesses. In addition, the fabrication of ohmic contacts for MoSe2-layer nanocrystals by the focused-ion beam deposition method using platinum (Pt) as a contact metal is described.

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor ...

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 ...

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 ...

Controllable Nucleation of Cavitation from Plasmonic Gold Nanoparticles for Enhancing High Intensity Focused Ultrasound Applications

In this study, plasmonic gold nanoparticles were simultaneously exposed to pulsed near-infrared laser light and high intensity focused ultrasound (HIFU) for the controllable nucleation of cavitation in tissue-mimicking gel phantoms. This in vitro protocol was developed to demonstrate the feasibility of this approach, for both enhancement of imaging and therapeutic applications for cancer. The same apparatus can be used for both imaging and therapeutic applications by varying the exposure duration of the HIFU system. For short duration exposures (10 &#181;s), broadband acoustic emissions were generated through the controlled nucleation of inertial cavitation around the gold nanoparticles. These emissions provide direct localization of nanoparticles. For future applications, these particles may be functionalized with molecular-targeting antibodies (e.g. anti-HER2 for breast cancer) and can provide precise localization of cancerous regions, complementing routine diagnostic ultrasound imaging. For continuous wave (CW) exposures, the cavitation activity was used to increase the localized heating from the HIFU exposures resulting in larger thermal damage in the gel phantoms. The acoustic emissions generated from inertial cavitation activity during these CW exposures was monitored using a passive cavitation detection (PCD) system to provide feedback of cavitation activity. Increased localized heating was only achieved through the unique combination of nanoparticles, laser light and HIFU. Further validation of this technique in pre-clinical models of cancer is necessary.

This protocol demonstrates the controllable nucleation of cavitation in gel phantoms, through simultaneous exposure to both near-infrared pulsed laser light and high intensity focused ultrasound (HIFU). The cavitation activity can then be used for enhancing imaging and/or therapeutic uses of HIFU.

In this study, plasmonic gold nanoparticles were simultaneously exposed to pulsed near-infrared laser light and high intensity focused ultrasound (HIFU) ...

Multiplexing Focused Ultrasound Stimulation with Fluorescence Microscopy

By focusing low-intensity ultrasound pulses that penetrate soft tissues, LIPUS represents a promising biomedical technology to remotely and safely manipulate neural firing, hormonal secretion and genetically-reprogrammed cells. However, the translation of this technology for medical applications is currently hampered by a lack of biophysical mechanisms by which targeted tissues sense and respond to LIPUS. A suitable approach to identify these mechanisms would be to use optical biosensors in combination with LIPUS to determine underlying signaling pathways. However, implementing LIPUS to a fluorescence microscope may introduce undesired mechanical artefacts due to the presence of physical interfaces that reflect, absorb and refract acoustic waves. This article presents a step-by-step procedure to incorporate LIPUS to commercially-available upright epi-fluorescence microscopes while minimizing the influence of physical interfaces along the acoustic path. A simple procedure is described to operate a single-element ultrasound transducer and to bring the focal zone of the transducer into the objective focal point. The use of LIPUS is illustrated with an example of LIPUS-induced calcium transients in cultured human glioblastoma cells measured using calcium imaging.

Low-Intensity Pulsed Ultrasound Stimulation (LIPUS) is a modality for non-invasive mechanical stimulation of endogenous or engineered cells with high spatial and temporal resolution. This article describes how to implement LIPUS to an epi-fluorescence microscope and how to minimize acoustic impedance mismatch along the ultrasound path to prevent unwanted mechanical artefacts.

By focusing low-intensity ultrasound pulses that penetrate soft tissues, LIPUS represents a promising biomedical technology to remotely and safely ...

Evaluating Usability Aspects of a Mixed Reality Solution for Immersive Analytics in Industry 4.0 Scenarios

In medicine or industry, the analysis of high-dimensional data sets is increasingly required. However, available technical solutions are often complex to use. Therefore, new approaches like immersive analytics are welcome. Immersive analytics promise to experience high-dimensional data sets in a convenient manner for various user groups and data sets. Technically, virtual-reality devices are used to enable immersive analytics. In Industry 4.0, for example, scenarios like the identification of outliers or anomalies in high-dimensional data sets are pursued goals of immersive analytics. In this context, two important questions should be addressed for any developed technical solution on immersive analytics: First, is the technical solutions being helpful or not? Second, is the bodily experience of the technical solution positive or negative? The first question aims at the general feasibility of a technical solution, while the second one aims at the wearing comfort. Extant studies and protocols, which systematically address these questions are still rare. In this work, a study protocol is presented, which mainly investigates the usability for immersive analytics in Industry 4.0 scenarios. Specifically, the protocol is based on four pillars. First, it categorizes users based on previous experiences. Second, tasks are presented, which can be used to evaluate the feasibility of the technical solution. Third, measures are presented, which quantify the learning effect of a user. Fourth, a questionnaire&#160;evaluates the stress level when performing tasks. Based on these pillars, a technical setting was implemented that uses mixed reality smartglasses to apply the study protocol. The results of the conducted study show the applicability of the protocol on the one hand and the feasibility of immersive analytics in Industry 4.0 scenarios on the other. The presented protocol includes a discussion of discovered limitations.

This protocol delineates the technical setting of a developed mixed reality application that is used for immersive analytics. Based on this, measures are presented, which were used in a study to gain insights into usability aspects of the developed technical solution.

In medicine or industry, the analysis of high-dimensional data sets is increasingly required. However, available technical solutions are often complex to ...