The application of this robotic technique was approved by the ethics committee of the Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, and it complies with the Helsinki Declaration of 1975, as revised in 2013.
1. Preoperative planning
<ol>
	<li>Fix the cadaveric pelves in the supine position using a fluoroscopic plate base (see Table of Materials) by inserting two Schanz pins through the femur. In the supine position, place both the posterior superior iliac spines simultaneously on the plank and the lumbar vertebrae parallel to the floor. 
	NOTE: The donated cadavers were embalmed by the Department of Anatomy and Research, Tongji Medical College, Huazhong University of Science and Technology. The pelvic specimens were obtained by transection at the level of the lumbar 5 vertebrae and below the lesser trochanter of the femur. The organs in the pelvic cavity were removed. The muscles, joint capsules, and ligamentous structures were left intact.</li>
	<li>Acquire images of the pelves from the upper edge of the L5 vertebrae to the distal femoral trochanter using a spiral CT (see Table of Materials). Process the computed tomography (CT) images of all the cadavers using the workstation, and store them in the DICOM format. 
	NOTE: CT parameters: 0.5 mm slice thickness, 63 mA current, 140 kV voltage.</li>
	<li>Import the CT scan data into the preoperative planning software (see Table of Materials) of this system in the DICOM format to obtain axial, coronal, and sagittal images of the pelvis. 
	NOTE: The DICOM files contain the information from the CT scan, and the reconstructed image can be obtained by automatic import.</li>
	<li>Create a cylinder using the MedCAD module of the software, and define the size of the cylinder by typing in the diameter and length. Place it into the S1 or S2 vertebral body, and adjust the orientation of the cylinder midline on the axial and coronal images. Check the relationship between the edge of the cylinder and the cortical bone in each image. 
	&#8203;NOTE: The cylinder entirely within the cancellous bone (excluding contact with the cortical bone) is considered to have a corresponding screw channel in S1 or S2. The length of the middle line of the cylinder is the length of the screw.</li>
</ol>
2. Surgical setting
<ol>
	<li>Fix the pelvis on the fluoroscopic operating table in the supine position (Figure 1).</li>
	<li>Place the Robot (see Table of Materials) on the ipsilateral side at 45&#176; to the operating table with the C-arm perpendicular to the operating table on the contralateral side. The monitor of the C-arm should face the operating room to enable the surgeon to observe it (Figure 1).</li>
	<li>Place the workstation of the MSOPGS and Slave Manipulator outside the operating room. The surgeon should be able to observe the surgical field and the C-arm monitor while teleoperating with the Slave-Manipulator (Figure 1).</li>
</ol>
3. Surgical procedure
NOTE: After the system is started and inspected, the manipulator is automatically deployed to the working state.
<ol>
	<li>Fix the grid position maker with adhesive tape on the ipsilateral side. Select the target area by a grid position marker on the true lateral view of the sacrum. Ensure that the manual traction mode on the console is selected and started. Drag the robotic arm to the general area of the S1 or S2 transiliac-transsacral screw entry point (Figure 3A, B). 
	NOTE: The target area is enclosed by the anterior border of the sacrum, the sacral nerve canal, and the spinal canal.</li>
	<li>Visualize the true lateral view of the sacrum, operate the Master Manipulator, and adjust the tip of the distal sleeve to be located in the guidewire entry area in the Master-Slave operation mode (Figure 3C).</li>
	<li>After selecting the RCM mode, continue the C-arm fluoroscopy for the lateral sacral view. Adjust the center of the guidewire sleeve into concentric circles to be consistent with the screw channel (Figure 3D).</li>
	<li>Lock the robotic arm, and insert a guidewire (2.5 mm K-wire, see Table of Materials) through the contralateral ilium using an electric drill. Then, remove the Robot in Manual traction mode (Figure 3E). 
	NOTE: No fluoroscopy should be performed during this step.</li>
	<li>Turn the C-arm to the inlet and outlet angles (different pelves have different angles) to determine whether the guidewire has broken through or contacted the anterior and posterior sacral cortex and the sacral nerve canal (Figure 3F, G).</li>
	<li>Insert a 7.3 mm semi-threaded screw (see Table of Materials) along the guidewire to the contralateral iliac cortex.</li>
	<li>Assess the screw position in the pelvic inlet and outlet view and the lateral view (Figure 4).</li>
</ol>
4. Postoperative assessment
<ol>
	<li>Perform steps 1.2-1.3. 
	NOTE: CT parameters: 0.5 mm slice thickness, 63 mA current, and 140 kV voltage.</li>
	<li>Check the screw position in each axial, coronal, and sagittal image. 
	NOTE: The screw positions were assessed using Gras&#39;s method. Specifically, screws in the cancellous bone are Grade I, screws in contact with the cortical bone are Grade II, and screws that penetrate the cortical bone are Grade III. Grade III represents screw misplacement and indicates a risk of vascular and nerve injury13.</li>
</ol>

<ol>
	<li>Bargar, W. L., Bauer, A., B&#246;rner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+and+revision+total+hip+replacement+using+the+Robodoc+system.">Primary and revision total hip replacement using the Robodoc system.</a> Clinical Orthopaedics and Related Research. (354), 82-91 (1998).</li><li>Jacofsky, D. J., Allen, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Robotics+in+arthroplasty:+A+comprehensive+review.">Robotics in arthroplasty: A comprehensive review.</a> Journal of Arthroplasty. 31 (10), 2353-2363 (2016).</li><li>Perfetti, D. C., Kisinde, S., Rogers-LaVanne, M. P., Satin, A. M., Lieberman, I. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Robotic+spine+surgery:+Past,+present+and+future.">Robotic spine surgery: Past, present and future.</a> Spine. 47 (13), 909-921 (2022).</li><li>Long, T., 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=Comparative+study+of+percutaneous+sacroiliac+screw+with+or+without+TiRobot+assistance+for+treating+pelvic+posterior+ring+fractures.">Comparative study of percutaneous sacroiliac screw with or without TiRobot assistance for treating pelvic posterior ring fractures.</a> Orthopaedic Surgery. 11 (3), 386-396 (2019).</li><li>Duan, S. J., 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=Robot-assisted+percutaneous+cannulated+screw+fixation+of+femoral+neck+fractures:+Preliminary+clinical+results.">Robot-assisted percutaneous cannulated screw fixation of femoral neck fractures: Preliminary clinical results.</a> Orthopaedic Surgery. 11 (1), 34-41 (2019).</li><li>Lei, H., Sheng, L., Manyi, W., Junqiang, W., Wenyong, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+biplanar+robot+navigation+system+for+the+distal+locking+of+intramedullary+nails.">A biplanar robot navigation system for the distal locking of intramedullary nails.</a> International Journal of Medical Robotics and Computer Assisted Surgery. 6 (1), 61-65 (2010).</li><li>Oszwald, 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=Robotized+access+to+the+medullary+cavity+for+intramedullary+nailing+of+the+femur.">Robotized access to the medullary cavity for intramedullary nailing of the femur.</a> Technology and Health Care. 18 (3), 173-180 (2010).</li><li>Hung, S. S., Lee, M. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+assessment+of+a+surgical+robot+for+reduction+of+lower+limb+fractures.">Functional assessment of a surgical robot for reduction of lower limb fractures.</a> International Journal of Medical Robotics and Computer Assisted Surgery. 6 (4), 413-421 (2010).</li><li>Dagnino, G., 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=Image-guided+surgical+robotic+system+for+percutaneous+reduction+of+joint+fractures.">Image-guided surgical robotic system for percutaneous reduction of joint fractures.</a> Annual Review of Biomedical Engineering. 45 (11), 2648-2662 (2017).</li><li>Garcia, 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=Trauma+Pod:+A+semi-automated+telerobotic+surgical+system.">Trauma Pod: A semi-automated telerobotic surgical system.</a> International Journal of Medical Robotics and Computer Assisted Surgery. 5 (2), 136-146 (2009).</li><li>Gaensslen, A., M&#252;ller, M., Nerlich, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Acetabular Fractures: Diagnosis, Indications, Treatment Strategies. , (2017).</li><li>LBR Med: A collaborative robot for medical applications. KUKA Available from: <a target="_blank" href="https://www.kuka.com/en-cn/industries/health-care/kuka-medical-robotics/lbr-med">https://www.kuka.com/en-cn/industries/health-care/kuka-medical-robotics/lbr-med</a> (2023)</li><li>Gras, F., 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=2D-fluoroscopic+navigated+percutaneous+screw+fixation+of+pelvic+ring+injuries--A+case+series.">2D-fluoroscopic navigated percutaneous screw fixation of pelvic ring injuries--A case series.</a> BMC Musculoskeletal Disorders. 11, 153 (2010).</li><li>Innocenti, B., Bori, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Robotics+in+orthopaedic+surgery:+Why,+what+and+how.">Robotics in orthopaedic surgery: Why, what and how.</a> Archives of Orthopaedic and Trauma Surgery. 141 (12), 2035-2042 (2021).</li><li>Chen, A. F., Kazarian, G. S., Jessop, G. W., Makhdom, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Robotic+technology+in+orthopaedic+surgery.">Robotic technology in orthopaedic surgery.</a> Journal of Bone and Joint Surgery. 100 (22), 1984-1992 (2018).</li><li>D'Souza, 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=Robotic-assisted+spine+surgery:+History,+efficacy,+cost,+and+future+trends.">Robotic-assisted spine surgery: History, efficacy, cost, and future trends.</a> Robotic surgery. 6, 9-23 (2019).</li><li>Dagnino, G., 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=Navigation+system+for+robot-assisted+intra-articular+lower-limb+fracture+surgery.">Navigation system for robot-assisted intra-articular lower-limb fracture surgery.</a> International Journal for Computer Assisted Radiology and Surgery. 11 (10), 1831-1843 (2016).</li><li>F&#252;chtmeier, B., 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=Reduction+of+femoral+shaft+fractures+in+vitro+by+a+new+developed+reduction+robot+system+'RepoRobo.">Reduction of femoral shaft fractures in vitro by a new developed reduction robot system 'RepoRobo.</a> Injury. 35, 113-119 (2004).</li><li>Schuijt, H. J., Hundersmarck, D., Smeeing, D. P. J., vander Velde, D., Weaver, 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=Robot-assisted+fracture+fixation+in+orthopaedic+trauma+surgery:+A+systematic+review.">Robot-assisted fracture fixation in orthopaedic trauma surgery: A systematic review.</a> OTA International. 4 (4), 153 (2021).</li><li>Wang, J. Q., 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=Percutaneous+sacroiliac+screw+placement:+A+prospective+randomized+comparison+of+robot-assisted+navigation+procedures+with+a+conventional+technique.">Percutaneous sacroiliac screw placement: A prospective randomized comparison of robot-assisted navigation procedures with a conventional technique.</a> Chinese Medical Journal. 130 (21), 2527-2534 (2017).</li><li>Zhu, Z. D., 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=TiRobot-assisted+percutaneous+cannulated+screw+fixation+in+the+treatment+of+femoral+neck+fractures:+A+minimum+2-year+follow-up+of+50+patients.">TiRobot-assisted percutaneous cannulated screw fixation in the treatment of femoral neck fractures: A minimum 2-year follow-up of 50 patients.</a> Orthopaedic Surgery. 13 (1), 244-252 (2021).</li><li>Gardner, M. J., Routt, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transiliac-transsacral+screws+for+posterior+pelvic+stabilization.">Transiliac-transsacral screws for posterior pelvic stabilization.</a> Journal of Orthopaedic Trauma. 25 (6), 378-384 (2011).</li><li>Verhey, J. T., Haglin, J. M., Verhey, E. M., Hartigan, D. 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The authors declare that they have no competing interests.

Regardless of the type of Robot, the core application of robots in orthopedics provides an advanced tool for surgeons to improve the accuracy of surgery. However, the emergence of surgical robots is not a replacement for doctors. Surgeons performing robotic surgery may or may not be in the operating room. Surgical robots generally include a computer control system, a robotic arm responsible for the operation, and a navigation system responsible for tracking. There are three categories of robot systems depending on how th...

The first robotic application utilized in orthopedic surgery was the ROBODOC system employed in 19921. Since then, robot-assisted surgical systems have rapidly developed. Robot-assisted surgery improves arthroplasty by enhancing the surgeon&#39;s ability to restore the alignment of the limb and the physiological kinematics of the joint2. In spinal surgery, the placement of pedicle screws using a robot is safe and accurate; it also reduces the surgeon&#39;s radiation exposure3. However, studies on robot-assisted surgery have been limited owing to the heterogeneity of traumatic orthopedic diseases. The existing research on robotic surgery for orthopedic trauma mainly focuses on robot-assisted sacroiliac joint screws and pubic-screw fixation of pelvic ring fractures4, cannulated screw fixation of the femoral neck5, entry point and distal locking bolts in intramedullary nailing6,7, percutaneous fracture reduction8,9, and the treatment of critically wounded patients in the military field10.
The percutaneous screw technique can be performed using 2D and 3D navigation support. The sacroiliac, anterior column, posterior column, supraacetabular, and magic screws are the most common percutaneous techniques for pelvic and acetabular factures11. The percutaneous transiliac-transsacral screw technique remains challenging for surgeons. An understanding of pelvic anatomy and X-ray fluoroscopy, accurate positioning, and long-term hand stability are required for this procedure. The teleoperated robotic system can meet these requirements well. This study utilizes a teleoperated robotic system to complete percutaneous transiliac-transsacral screw fixation for pelvic ring fractures. The details and workflow of this protocol are presented below.
Robotic system 
The Master-Slave Orthopaedic Positioning and Guidance System (MSOPGS) is mainly composed of three parts: the surgical Robot (Slave Manipulator) with seven degrees of freedom (DOF), the Master Manipulator with force feedback, and the console. The system has four operating modes: manual traction, master-slave operation, remote center of motion (ROM), and emergency. Figure 1 shows the MSOPPGS; its main components are briefly described below.
The surgical robot (see Table of Materials) is a seven DOF manipulator that is pre-certified for integration into medical products12. The Robot has force-feedback sensors that can detect changes in force. The robotic arm can be operated manually or remotely. A torque sensor is installed at the tip and mapped to the &#34;Master Manipulator,&#34; enabling real-time force feedback. The maximum load on the robotic arm is sufficient to resist soft tissue forces and reduce the fluttering of the surgical instruments. The Robot is attached to a mobile platform to acquire an operational workplace and ensure stability. The base is connected to the &#34;Master Manipulator&#34; and the operative system and can process instructions from the operative system.
The &#34;Master Manipulator&#34; is designed for healthcare industries to precisely control the Robot. This device offers seven active DOF, including high-precision force-feedback grasping capabilities. Its end effector covers the natural range of motion of the human hand. An incremental control strategy is used to achieve intuitive control of the robotic arm.
The operative system provides four methods for controlling the robotic arm: manual traction, master-slave operation mode, remote centre of motion (RCM), and emergency. The operative system links the surgeon and Robot and provides safety alarms. The manual traction mode allows the manipulator to be dragged freely within a specific working range. The Robot is automatically locked after being stopped for 5 s. In the master-slave mode, the surgeon can use the &#34;Master Manipulator&#34; to control the movement of the robotic arm. The RCM mode permits the surgical instrument to pivot around the end of the instrument. The RCM mode is best suited to reorientation on the axial fluoroscopy view of the channel, such as the radiographic teardrop sign of the supraacetabular channel and the true sacral view of the transiliac-transsacral osseous pathway. The manipulator can be used for emergency braking at any position. Figure 2 shows the workflow of the system.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>160-slice CT</td>
			<td>United Imaging Healthcare Surgical Technology Co. Ltd</td>
			<td>uCT780</td>
			<td>Acquire the prescise image and DICOM data</td>
		</tr>
		<tr>
			<td>Electric bone drill</td>
			<td>YUTONG Medical</td>
			<td>None</td>
			<td>Power system</td>
		</tr>
		<tr>
			<td>Fluoroscopic plate base</td>
			<td>None</td>
			<td>None</td>
			<td>Fix the cadaveric pelves to operating table</td>
		</tr>
		<tr>
			<td>K-wire</td>
			<td>None</td>
			<td>2.5mm</td>
			<td>Guidewire</td>
		</tr>
		<tr>
			<td>Master-Slave Orthopaedic Positioning and Guidance System</td>
			<td>United Imaging Healthcare Surgical Technology Co. Ltd</td>
			<td>None</td>
			<td>A teleoperated robotic system that positions screws for orthopaedic surgery</td>
		</tr>
		<tr>
			<td>Mimics Innovation Suite</td>
			<td>Materialise</td>
			<td>Mimics Medical 21</td>
			<td>Preoperative planning software &#160;&#160;</td>
		</tr>
		<tr>
			<td>Mobile C-arm</td>
			<td>United Imaging Healthcare Surgical Technology Co. Ltd</td>
			<td>uMC560i</td>
			<td>Low Dose CMOS Mobile C-arm</td>
		</tr>
		<tr>
			<td>Operating table&#160;</td>
			<td>KELING</td>
			<td>DL&#183;C-I</td>
			<td>Fluoroscopic surgical table</td>
		</tr>
		<tr>
			<td>Schanz pins</td>
			<td>Tianjin ZhengTian Medical Instrument Co.,Ltd.</td>
			<td>5.0mm</td>
			<td>Fix the cadaveric pelves</td>
		</tr>
		<tr>
			<td>Semi-threaded screw</td>
			<td>Tianjin ZhengTian Medical Instrument Co.,Ltd.</td>
			<td>7.3mm</td>
			<td>Transiliac-Transsacral Screw</td>
		</tr>
		<tr>
			<td>Seven DOF manipulator</td>
			<td>KUKA, Germany</td>
			<td>LBR Med 7 R800</td>
			<td>Device for performing surgical operations</td>
		</tr>
	</tbody>
</table>

a teleoperated robotic system-assisted percutaneous transiliac-transsacral screw fixation technique

Transiliac-transsacral screw fixation is challenging in clinical practice as the screws need to break through six layers of cortical bone. Transiliac-transsacral screws provide a longer lever arm to withstand the perpendicular vertical shear forces. However, the screw channel is so long that a minor discrepancy can lead to iatrogenic neurovascular injuries. The development of medical robots has improved the precision of surgery. The present protocol describes how to use a new teleoperated robotic system to execute transiliac-transacral screw fixation. The Robot was operated remotely to position the entry point and adjust the orientation of the sleeve. The screw positions were evaluated using postoperative computed tomography (CT). All the screws were safely implanted, as confirmed using intraoperative fluoroscopy. Postoperative CT confirmed that all the screws were in the cancellous bone. This system combines the doctor's initiative with the Robot's stability. The remote control of this procedure is possible. Robot-assisted surgery has a higher position-retention capacity compared with conventional methods. In contrast to active robotic systems, surgeons have full control over the operation. The robot system is fully compatible with operating room systems and does not require additional equipment.

A senior orthopedic surgeon completed the surgery using the procedure described. All the screws (three in S1 and two in S2) were secured. The time taken (from the first X-ray fluoroscopy to the insertion of the screw) for inserting each of the five screws was 32 min, 28 min, 26 min, 20 min, and 23 min, respectively. The fluoroscopy time for each screw was approximately 5 min. Although all the screws were in the correct place on the intraoperative fluoroscopic images, several articles have highlighted the need for postope...

Watch this Scientific Journal Video about A Teleoperated Robotic System-Assisted Percutaneous Transiliac-Transsacral Screw Fixation Technique at JoVE.com

A Teleoperated Robotic System-Assisted Percutaneous Transiliac-Transsacral Screw Fixation Technique

Teleoperated robotic system-assisted percutaneous transiliac-transsacral screw fixation is a feasible technique. Screw channels can be implemented with high accuracy owing to the excellent freedom of movement and stability of the robotic arms.

Transiliac-transsacral screw fixation is challenging in clinical practice as the screws need to break through six layers of cortical bone. ...

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Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

2.2K Views.  Huazhong University of Science and Technology. Teleoperated robotic system-assisted percutaneous transiliac-transsacral screw fixation is a feasible technique. Screw channels can be implemented with high accuracy owing to the excellent freedom of movement and stability of the robotic arms.

Video: A Teleoperated Robotic System-Assisted Percutaneous Transiliac-Transsacral Screw Fixation Technique

Time Multiplexing Super Resolving Technique for Imaging from a Moving Platform

We propose a method for increasing the resolution of an object and overcoming the diffraction limit of an optical system installed on top of a moving imaging system, such as an airborne platform or satellite. The resolution improvement is obtained in a two-step process. First, three low resolution differently defocused images are being captured and the optical phase is retrieved using an improved iterative Gerchberg-Saxton based algorithm. The phase retrieval allows to numerically back propagate the field to the aperture plane. Second, the imaging system is shifted and the first step is repeated. The obtained optical fields at the aperture plane are combined and a synthetically increased lens aperture is generated along the direction of movement, yielding higher imaging resolution. The method resembles a well-known approach from the microwave regime called the Synthetic Aperture Radar (SAR) in which the antenna size is synthetically increased along the platform propagation direction. The proposed method is demonstrated through laboratory experiment.

A method for overcoming the optical diffraction limit is presented. The method includes a two-step process: optical phase retrieval using iterative Gerchberg-Saxton algorithm, and imaging system shifting followed by repetition of the first step. A synthetically increased lens aperture is generated along the direction of movement, yielding higher imaging resolution.

We propose a method for increasing the resolution of an object and overcoming the diffraction limit of an optical system installed on top of a moving ...

Fast Imaging Technique to Study Drop Impact Dynamics of Non-Newtonian Fluids

In the field of fluid mechanics, many dynamical processes not only occur over a very short time interval but also require high spatial resolution for detailed observation, scenarios that make it challenging to observe with conventional imaging systems. One of these is the drop impact of liquids, which usually happens within one tenth of millisecond. To tackle this challenge, a fast imaging technique is introduced that combines a high-speed camera (capable of up to one million frames per second) with a macro lens with long working distance to bring the spatial resolution of the image down to 10 &#181;m/pixel. The imaging technique enables precise measurement of relevant fluid dynamic quantities, such as the flow field, the spreading distance and the splashing speed, from analysis of the recorded video. To demonstrate the capabilities of this visualization system, the impact dynamics when droplets of non-Newtonian fluids impinge on a flat hard surface are characterized. Two situations are considered: for oxidized liquid metal droplets we focus on the spreading behavior, and for densely packed suspensions we determine the onset of splashing. More generally, the combination of high temporal and spatial imaging resolution introduced here offers advantages for studying fast dynamics across a wide range of microscale phenomena.

Drop impact of non-Newtonian fluids is a complex process since different physical parameters influence the dynamics over a very short time (less than one tenth of a millisecond). A fast imaging technique is introduced in order to characterize the impact behaviors of different non-Newtonian fluids.

In the field of fluid mechanics, many dynamical processes not only occur over a very short time interval but also require high spatial resolution for ...

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 ...

Prescribed 3-D Direct Writing of Suspended Micron/Sub-micron Scale Fiber Structures via a Robotic Dispensing System

A 3-axis dispensing system is utilized to control the initiating and terminating fiber positions and trajectory via the dispensing software. The polymer fiber length and orientation is defined by the spatial positioning of the dispensing system 3-axis stages. The fiber diameter is defined by the prescribed dispense time of the dispensing system valve, the feed rate (the speed at which the stage traverses from an initiating to a terminating position), the gauge diameter of the dispensing tip, the viscosity and surface tension of the polymer solution, and the programmed drawing length. The stage feed rate affects the polymer solution&#8217;s evaporation rate and capillary breakup of the filaments. The dispensing system consists of a pneumatic valve controller, a droplet-dispensing valve and a dispensing tip. Characterization of the direct write process to determine the optimum combination of factors leads to repeatedly acquiring the desired range of fiber diameters. The advantage of this robotic dispensing system is the ease of obtaining a precise range of micron/sub-micron fibers onto a desired, programmed location via automated process control. Here, the discussed self-assembled micron/sub-micron scale 3D structures have been employed to fabricate suspended structures to create micron/sub-micron fluidic devices and bioengineered scaffolds.

Here, we present a protocol to fabricate freely-suspended, micron/sub-micron scale polymer fibers and &#8220;web-like&#8221; structures generated via automated direct writing procedure by means of a 3-axis dispensing system.

A 3-axis dispensing system is utilized to control the initiating and terminating fiber positions and trajectory via the dispensing software. The polymer ...

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 ...

Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film synthesis) for the purpose of exploratory materials research. Certain materials pose a challenge wherein the traditional bulk Hall bar device fabrication method is insufficient to produce a measureable device for sample transport measurement, principally because the single crystal size is too small to attach wire leads to the sample in a Hall bar configuration. This can be, for example, because the first batch of a new material synthesized yields very small single crystals or because flakes of samples of one to very few monolayers are desired. In order to enable rapid characterization of materials that may be carried out in parallel with improvements to their growth methodology, a method of device fabrication for very small samples has been devised to permit the characterization of novel materials as soon as a preliminary batch has been produced. A slight variation of this methodology is applicable to producing devices using exfoliated samples of two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs), as well as multilayer heterostructures of such materials. Here we present detailed protocols for the experimental device fabrication of fragments and flakes of novel materials with micron-sized dimensions onto substrate and subsequent measurement in a commercial superconducting magnet, dry helium close-cycle cryostat magnetotransport system at temperatures down to 0.300 K and magnetic fields up to 12 T.

We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film ...

Light Enhanced Hydrofluoric Acid Passivation: A Sensitive Technique for Detecting Bulk Silicon Defects

A procedure to measure the bulk lifetime (&#62;100 &#181;sec) of silicon wafers by temporarily attaining a very high level of surface passivation when immersing the wafers in hydrofluoric acid (HF) is presented. By this procedure three critical steps are required to attain the bulk lifetime. Firstly, prior to immersing silicon wafers into HF, they are chemically cleaned and subsequently etched in 25% tetramethylammonium hydroxide. Secondly, the chemically treated wafers are then placed into a large plastic container filled with a mixture of HF and hydrochloric acid, and then centered over an inductive coil for photoconductance (PC) measurements. Thirdly, to inhibit surface recombination and measure the bulk lifetime, the wafers are illuminated at 0.2 suns for 1 min&#160;using a halogen lamp, the illumination is switched off, and a PC measurement is immediately taken. By this procedure, the characteristics of bulk silicon defects can be accurately determined. Furthermore, it is anticipated that a sensitive RT surface passivation technique will be imperative for examining bulk silicon defects when their concentration is low (&#60;1012 cm-3).

A RT liquid surface passivation technique to investigate the recombination activity of bulk silicon defects is described. For the technique to be successful, three critical steps are required: (i) chemical cleaning and etching of silicon, (ii) immersion of silicon in 15% hydrofluoric acid and (iii) illumination for 1 min.

A procedure to measure the bulk lifetime (&#62;100 &#181;sec) of silicon wafers by temporarily attaining a very high level of surface passivation when ...

A Robotic Platform to Study the Foreflipper of the California Sea Lion

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most of their thrust with their large foreflippers. This protocol describes a robotic platform designed to study the hydrodynamic performance of the swimming California sea lion (Zalophus californianus). The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;). The kinematics of the sea lion&#39;s propulsive stroke are extracted from video data of unmarked, non-research sea lions at the Smithsonian Zoological Park (SNZ). Those data form the basis of the actuation motion of the robotic flipper presented here. The geometry of the robotic flipper is based a on high-resolution laser scan of a foreflipper of an adult female sea lion, scaled to about 60% of the full-scale flipper. The articulated model has three joints, mimicking the elbow, wrist and knuckle joint of the sea lion foreflipper. The robotic platform matches dynamics properties&#8212;Reynolds number and tip speed&#8212;of the animal when accelerating from rest. The robotic flipper can be used to determine the performance (forces and torques) and resulting flowfields.

A robotic platform is described that will be used to study the hydrodynamic performance&#8212;forces and flowfields&#8212;of the swimming California sea lion. The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;).

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most ...

Magnet Assisted Composite Manufacturing: A Flexible New Technique for Achieving High Consolidation Pressure in Vacuum Bag/Lay-Up Processes

This work demonstrates a protocol to improve the quality of composite laminates fabricated by wet lay-up vacuum bag processes using the recently developed magnet assisted composite manufacturing (MACM) technique. In this technique, permanent magnets are utilized to apply a sufficiently high consolidation pressure during the curing stage. To enhance the intensity of the magnetic field, and thus, to increase the magnetic compaction pressure, the magnets are placed on a magnetic top plate. First, the entire procedure of preparing the composite lay-up on a magnetic bottom steel plate using the conventional wet lay-up vacuum bag process is described. Second, placement of a set of Neodymium-Iron-Boron permanent magnets, arranged in alternating polarity, on the vacuum bag is illustrated. Next, the experimental procedures to measure the magnetic compaction pressure and volume fractions of the composite constituents are presented. Finally, methods used to characterize microstructure and mechanical properties of composite laminates are discussed in detail. The results prove the effectiveness of the MACM method in improving the quality of wet lay-up vacuum bag laminates. This method does not require large capital investment for tooling or equipment and can also be used to consolidate geometrically complex composite parts by placing the magnets on a matching top mold positioned on the vacuum bag.

A new technique for applying consolidation pressure on the vacuum bag lay-up to fabricate composite laminates is described. The goal of this protocol is to develop a simple, cost-effective technique to improve the quality of laminates fabricated by the wet lay-up vacuum bag method.

This work demonstrates a protocol to improve the quality of composite laminates fabricated by wet lay-up vacuum bag processes using the recently developed ...

Design and Implementation of a Bespoke Robotic Manipulator for Extra-corporeal Ultrasound

With the potential for high precision, dexterity, and repeatability, a self-tracked robotic system can be employed to assist the acquisition of real-time ultrasound. However, limited numbers of robots designed for extra-corporeal ultrasound have been successfully translated into clinical use. In this study, we aim to build a bespoke robotic manipulator for extra-corporeal ultrasound examination, which is lightweight and has a small footprint. The robot is formed by five specially shaped links and custom-made joint mechanisms for probe manipulation, to cover the necessary range of motion with redundant degrees of freedom to ensure the patient&#39;s safety. The mechanical safety is emphasized with a clutch mechanism, to limit the force applied to patients. As a result of the design, the total weight of the manipulator is less than 2 kg and the length of the manipulator is about 25 cm. The design has been implemented, and simulation, phantom, and volunteer studies have been performed, to validate the range of motion, the ability to make fine adjustments, mechanical reliability, and the safe operation of the clutch. This paper details the design and implementation of the bespoke robotic ultrasound manipulator, with the design and assembly methods illustrated. Testing results to demonstrate the design features and clinical experience of using the system are presented. It is concluded that the current proposed robotic manipulator meets the requirements as a bespoke system for extra-corporeal ultrasound examination and has great potential to be translated into clinical use.

This paper introduces the design and implementation of a bespoke robotic manipulator for extra-corporeal ultrasound examination. The system has five degrees of freedom with lightweight joints made by 3D printing and a mechanical clutch for safety management.

With the potential for high precision, dexterity, and repeatability, a self-tracked robotic system can be employed to assist the acquisition of real-time ...