This work was supported by the NSF (CMMI-1351370).

1. Design Masks for Fabrication of Donor Substrate
<ol>
	<li>Design a mask with desired geometry. To fabricate 100 &#956;m x 100 &#956;m square silicon individual units, draw an array of 100 &#956;m x 100 &#956;m squares.</li>
	<li>Design a second mask with an identical geometry, with each side extending out an additional 15 &#956;m. For the array of 100 &#956;m x 100 &#956;m squares, draw an array of 130 &#956;m x 130 &#956;m squares that can cover the squares in step 1.1.</li>
	<li>Design the anchor geometry. Draw four 20 &#956;m x 40 &#956;m rectangles, each centered along one edge of a square. Place the structures so that the first 15 &#956;m covers the original 100 &#956;m x 100 &#956;m square in step 1.1 and the remaining 25 &#956;m extends outward (as shown in Figure 2). 
	NOTE: Any shape and dimensions can be used as long as the anchor contacts both the patterned material and the substrate. One end of this anchor covers the original geometry in step 1.1 and the other end should extend out the geometry in step 1.2.</li>
</ol>
2. Prepare Retrievable Donor Substrate
<ol>
	<li>Prepare a p-type doped silicon on insulator (SOI) wafer with 3 &#956;m device layer thickness, with sheet resistance of 1-20 &#937;&#8226;cm and box oxide layer thickness of 1 &#956;m. NOTE: For various applications these parameters can be altered.</li>
	<li>Spin coat photoresist (AZ5214, 3,000 rpm for 30 sec, 1.5 &#956;m thick) and attach the mask designed in step 1.1.</li>
	<li>Using a reactive ion etching (RIE) instrument, pattern the device layer of the SOI wafer and remove photoresist mask. After this step, the RIE etched region has exposed the box oxide layer (Figure 2A).</li>
	<li>Spin coat photoresist (AZ5214, 3,000 rpm for 30 sec, 1.5 &#956;m thick) and pattern with mask designed in step 1.2.</li>
	<li>Heat the wafer at 125 &#176;C for 90 sec on a hot plate.</li>
	<li>Immerse the wafer into 49% HF for 50 sec to etch the exposed box oxide layer from step 2.3. After completely drying, remove the masking photoresist (Figure 2B).</li>
	<li>Spin coat (AZ5214, 3,000 rpm for 30 sec, 1.5 &#956;m thick) and pattern the anchoring design from step 1.3.</li>
	<li>Heat the wafer at 125 &#176;C for 90 sec on a hot plate.</li>
	<li>Immerse into 49% HF for 50 min. This step etches the box oxide layer remaining underneath the remaining patterned device layer silicon, resulting in suspended silicon individual units on the photoresist (Figure 2C).</li>
</ol>
3. Design Masks for a Microtip Stamp
<ol>
	<li>Design a mask with a single 100 &#956;m x 100 &#956;m square.</li>
	<li>Design a mask with multiple 12 &#956;m x 12 &#956;m squares inside a 100 &#956;m x 100 &#956;m area.</li>
</ol>
4. Make the Mold for a Microtip Stamp
<ol>
	<li>Clean a silicon wafer with crystalline orientation of &#60;1-0-0&#62;, deposit 100 nm of silicon nitride using Plasma Enhanced Chemical Vapor Deposition (PECVD) equipment.</li>
	<li>Spin coat photoresist (AZ5214, 3,000 rpm for 30 sec, 1.5 &#956;m thick) and pattern with mask designed in step 3.2.</li>
	<li>Pattern the silicon nitride layer using 10:1 Buffered Oxide Etchant (BOE).</li>
	<li>Dissolve 80 g of potassium hydroxide (KOH) in 170 ml of deionized water and 40 ml of isopropyl alcohol (IPA) mixture a beaker.</li>
	<li>Heat the KOH, IPA, and water mixture at 80 &#176;C on a hot plate.</li>
	<li>Vertically place the prepared wafer in the beaker with KOH mixture to etch the exposed silicon in crystalline structure (etching rate is around 1 &#956;m/min).</li>
	<li>After the exposed silicon is fully etched, remove the wafer from KOH mixture, etch away the silicon nitride using HF, and perform RCA 1 and RCA 2 cleaning (Figure 3A).</li>
	<li>Spin coat with SU-8 100 and pattern with the prepared mask from step 3.1 with following recipe: 3,000 rpm for 1 min, soft bake at 65 &#176;C for 10 min and 95 &#176;C for 30 min, expose with 550 mJ/cm2, and post bake at 65 &#176;C for 1 min and 95 &#176;C for 10 min (Figure 3B).</li>
	<li>After the SU-8 100 is fully cured, apply a monolayer of (tridecafluoro-1,1,2,3-tetrahydro octyl)-1-trichlorosilane by dropping 3-5 drops of (tridecafluoro-1,1,2,3-tetrahydro octyl)-1-trichlorosilane into a vacuum jar and placing the wafer in the jar and applying the vacuum.</li>
</ol>
5. Duplicate a Microtip Stamp Using a Mold
<ol>
	<li>Mix polydimethylsiloxane (PDMS) base and curing agent with the ratio of 5:1.</li>
	<li>Degas the mixture by placing it in a vacuum jar.</li>
	<li>Pour a small portion of the degassed PDMS mixture on the mold and let the PDMS reflow to achieve a flat top surface (Figure 3C).</li>
	<li>Place the mold with PDMS in the oven at 70 &#176;C for 2 hr to fully cure the PDMS.</li>
	<li>Remove the mold from the oven and peel the PDMS off (Figure 3D).</li>
</ol>
6. Retrieve Ink from the Donor Substrate and Print on the Target Area
<ol>
	<li>Place the donor substrate onto motorized rotational and x,y-translation stages equipped with a microscope.</li>
	<li>Attach the microtip stamp to an independent vertical translational stage.</li>
	<li>Under the microscope, align the microtip stamp with the Si ink on the donor substrate using translational and rotational stages. Furthermore, do the tilting alignment between the microtip surface and the Si ink by adjusting a tilting stage. Afterwards, bring the microtip stamp down to make contact.</li>
	<li>Slowly bring the microtip stamp down further after initial contact, so that small tips are fully collapsed and the whole surface is in contact with the Si ink on donor substrate.</li>
	<li>Quickly raise the z stage, breaking the anchors due to the large contact area between the microtip stamp and the Si ink, to retrieve the Si ink from the donor substrate and attach it to the microtip stamp. 
	NOTE: When the microtip stamp is free of any stress, the compressed microtip restores to its original pyramidal shape, making minimal contact with the retrieved Si ink.</li>
	<li>Place the receiver substrate onto an x,y-translation stage and align the retrieved Si ink under the microtip stamp at the desired location.</li>
	<li>Descend the z stage until the retrieved Si ink barely makes contact with the receiver substrate.</li>
	<li>After making contact, slowly raise the z stage to release the Si ink, printing it on the desired location.</li>
</ol>
7. Bonding Process
<ol>
	<li>Program a rapid thermal annealing furnace to cycle from RT up to 950 &#176;C in 90 sec, remain at 950 &#176;C for 10 min and cool down to RT (by removing any heat supply in the furnace).</li>
	<li>Place the printed receiver substrate in the furnace in an ambient air environment and anneal at 950 &#176;C for 10 min for Si-Si bonding or at 360 &#176;C for 30 min for Si-Au bonding.</li>
</ol>

<ol>
	<li>Stix, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toward+&#8220;Point+one.">Toward &#8220;Point one.</a> Sci Am. Feb. , 90-95 (1995).</li><li>Appenzeler, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Man+Who+Dared+to+Think+Small.">The Man Who Dared to Think Small.</a> Science. 254, 1300-1301 (1991).</li><li>Madou, 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=Fundamentals+of+Microfabrications+The+Science+of+Miniaturization.">Fundamentals of Microfabrications The Science of Miniaturization.</a> , (2002).</li><li>Xia, Y., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Soft+Lithography.">Soft Lithography.</a> Angew Chem Int Ed. 38, 551-575 (1998).</li><li>Judy, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microelectromechanical+systems+(MEMS)+fabrication,+design+and+applications.">Microelectromechanical systems (MEMS) fabrication, design and applications.</a> Smart Mater Struct. 10, 1134-1154 (2001).</li><li>Jain, V. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Micromanufacturing Process. , (2012).</li><li>Keum, 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=Silicon+micro-masonry+using+elastomeric+stamps+for+three-dimensional+microfabrication.">Silicon micro-masonry using elastomeric stamps for three-dimensional microfabrication.</a> J Micromech Microeng. 22, 55018 (2012).</li><li>Keum, H., Chung, H., Kim, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+Contact+at+The+Interface+between+Silicon+and+Transfer-Printed+Gold+Films+by+Eutectic+Joining.">Electrical Contact at The Interface between Silicon and Transfer-Printed Gold Films by Eutectic Joining.</a> ACS Appl Mater Interfaces. 5, 6061 (2013).</li><li>Keum, H., Seong, M., Sinha, S., Kim, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrostatically+Driven+Collapsible+Au+Thin+Films+Assembled+Using+Transfer+Printing+for+Thermal+Switching.">Electrostatically Driven Collapsible Au Thin Films Assembled Using Transfer Printing for Thermal Switching.</a> Appl Phys Lett. 100, 211904 (2012).</li><li>Klaassen, E. 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=Silicon+fusion+bonding+and+deep+reactive+ion+etching:+a+new+technology+for+microstructures.">Silicon fusion bonding and deep reactive ion etching: a new technology for microstructures.</a> Sens Actuators A. 52, 132-139 (1996).</li><li>Barth, P. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silicon+fusion+bonding+for+fabrication+of+sensors+actuators+and+microstructures.">Silicon fusion bonding for fabrication of sensors actuators and microstructures.</a> Sens Actuators. A21 - A23, 919-926 (1990).</li></ol>

The authors have nothing to disclose.

Micro-masonry, presented in Figure 4, involves silicon fusion bonding in a material bonding step. Silicon fusion bonding is achieved by placing the sample in a rapid thermal annealing furnace (RTA furnace) and heating the sample at 950 &#176;C for 10 min. This annealing condition is both adoptable between Si &#8211; Si and Si &#8211; SiO2 bonding10,11. Alternatively, the Au bonded with a Si strip as found in Figure 5C&#160;adopts eutectic bonding, and therefore, the bonding temperature is around the Si-Au eutectic temperature (363 &#176;C) for 30 min&#160;8. To ensure eutectic bonding, prior to printing Au inks on a Si strip, the Si strip needs to be thoroughly cleansed with 49% HF in order to prevent any impurity such as native oxide at the interface of the Au and Si. Being able to assemble Au films with micro-masonry hugely improves wide adaptation of the micro-masonry manufacturing scheme since it introduces a metal type of material. Due to its low electrical contact resistance with silicon, it can be used as an electrode in the finalized MEMS devices as well as a suspended membrane flexure as presented in Keum et al.9
Transferrable inks developed are currently limited to Si and Au and the materials of their corresponding receiver substrates are Si and SiO2 for Si, and Au and Si for Au. Overall, larger contact area between a receiver substrate and an ink results in ease in the printing step. However, printing an ink while partially contacting the surface is also feasible, resulting in suspended structure, as demonstrated in Figure 4E.
While micro-masonry is a novel approach of microfabrication, there still are limitations to overcome in the process. First and far most is manufacturing scalability since the current deterministic assembly of solid inks is conducted individually rather than at the same time. Also, since the silicon fusion bonding is exercised in high temperature, differences in Si and SiO2 thermal expansion coefficient may result in buckling/delamination in the interface. These limitations need to be further investigated for more broad adaptation of the micro-masonry technique.
As presented in Figure 4, micro-masonry has an immense influence on conventional MEMS processes, which mainly rely on monolithic microfabrication, through its unique additive and flexible manufacturing capability of three dimensional microscale structures that is previously unseen. Furthermore, micro-masonry has the ability to manipulate delicate features in the microscale without damaging the surface because it uses soft elastomeric stamps. Future work includes parallel transfer printing to reduce assembly time, localized bonding processes enabled by laser-assisted annealing, and extending this process to diverse MEMS materials such as SiO2, SixNy, Al, etc.

Microelectromechanical systems (MEMS), such as the miniaturization of large scale ordinary 3D machines, are indispensable for advancing modern technologies by providing performance enhancements and manufacturing cost reduction1,2. However, the current rate of technological advancement in MEMS cannot be maintained without continuous innovations in manufacturing technologies3-6. Common monolithic microfabrication primarily relies on layer-by-layer processes developed for the manufacture of integrated circuits (IC). This method has been quite successful at enabling mass production of high performance MEMS devices. However, owing to its complex layer-by-layer and electrochemically subtractive nature, manufacturing of diversely-shaped 3D MEMS structures and devices, while easy in the macroworld, is very challenging to achieve using this monolithic microfabrication. To enable more flexible 3D microfabrication with less process complexity, we developed a 3D additive micromanufacturing strategy (termed &#8216;micro/nano-masonry&#8217;) which involves a transfer printing-based assembly of micro/nanoscale materials in conjunction with rapid thermal annealing-enabled material bonding techniques.
Transfer printing is a method to transfer solid microscale materials (i.e.,&#160;&#8216;solid inks&#8217;) from a substrate where they are generated or grown to a different substrate by using controlled dry adhesion of elastomeric stamps. The typical procedure of micro-masonry starts with transfer printing. Prefabricated solid inks are transfer printed using a microtip stamp that is an advanced form of elastomeric stamps and the printed structures are subsequently annealed using rapid thermal annealing (RTA) to enhance ink-ink and ink-substrate adhesion. This manufacturing approach enables the construction of unusual microscale structures and devices that cannot be accommodated using other existing methods7.
Micro-masonry provides several attractive features not present in other methods: (a) the ability to integrate functional and structural solid inks of dissimilar materials to assemble MEMS sensors and actuators all integrated within the 3D structure; (b) the interfaces of assembled solid inks can function as electrical and thermal contacts9,10; (c) the assembly spatial resolution can be high (~1 &#956;m) by utilizing highly-scalable and well-understood lithographic processes for generating solid inks and highly-precise mechanical stages for transfer printing7; and (d) functional and structural solid inks can be integrated on both rigid and flexible substrates in planar or curvilinear geometries.

<table border="0" cellpadding="0" cellspacing="0" width="758">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:217px;">Name of Material / Equipment</td>
			<td style="width:97px;">Company</td>
			<td style="width:97px;"></td>
			<td style="width:347px;">Comments / Description</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Az 5214</td>
			<td>Clariant</td>
			<td></td>
			<td>1.5 mm thick photoresist</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Su8-100</td>
			<td>Microchem</td>
			<td></td>
			<td>100 mm Photoresist used in mold</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Sylgard 184</td>
			<td>Dow Corning</td>
			<td></td>
			<td>PDMS mixed to fabricate stamp</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Hydrofluoric Acid</td>
			<td>Honeywell</td>
			<td></td>
			<td>Acid to etch silicon oxide layer</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Silicon on insulator</td>
			<td>Ultrasil</td>
			<td></td>
			<td>Donor substrate was fabricated</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">trichlorosilane</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td>Chemical used to help pealing of PDMS from mold</td>
		</tr>
	</tbody>
</table>

micro-masonry for 3d additive micromanufacturing

Transfer printing is a method to transfer solid micro/nanoscale materials (herein called &#8216;inks&#8217;) from a substrate where they are generated to a different substrate by utilizing elastomeric stamps. Transfer printing enables the integration of heterogeneous materials to fabricate unexampled structures or functional systems that are found in recent advanced devices such as flexible and stretchable solar cells and LED arrays. While transfer printing exhibits unique features in material assembly capability, the use of adhesive layers or the surface modification such as deposition of self-assembled monolayer (SAM) on substrates for enhancing printing processes hinders its wide adaptation in microassembly of microelectromechanical system (MEMS) structures and devices. To overcome this shortcoming, we developed an advanced mode of transfer printing which deterministically assembles individual microscale objects solely through controlling surface contact area without any surface alteration. The absence of an adhesive layer or other modification and the subsequent material bonding processes ensure not only mechanical bonding, but also thermal and electrical connection between assembled materials, which further opens various applications in adaptation in building unusual MEMS devices.

Micro-masonry enables heterogeneous material integration to generate MEMS structures that are very challenging or impossible to achieve by monolithic microfabrication processes. In order to demonstrate its capability, a structure (called a &#8216;micro teapot&#8217;) is fabricated solely through micro-masonry. Figure 4A&#160;is an optical microscope image of fabricated Si inks on a donor substrate. The designed inks are discs with different dimensions made of single crystalline silicon, which are the building blocks of the micro teapot. Once a donor substrate is independently prepared, discs are transfer printed onto a receiver substrate and annealed layer by layer utilizing a microtip stamp as shown in Figure 4B. The inner region of the micro teapot is hollow as can be seen from each assembled disc. Furthermore, the delicateness of micro-masonry processes is also tested by transfer printing and annealing a rather exquisite photonic crystal platelet (Figures 4C-E). Photonic surfaces are first patterned with nanoimprint lithography and made as transferrable inks on a donor substrate as outlined in the protocol. Once the ink is fully prepared, the photonic crystal platelet is transferred onto four Si rings with 50 &#956;m thickness, forming a table like configuration shown in Figure 4E.
Apart from micro-masonry for silicon inks, images in Figure 5 show examples of micro-masonry adopted to assemble thin Au films. Figure 5A&#160;is an optical microscope image of prepared 400 nm thick Au films on a donor substrate. These inks are further processed and tested to transfer print onto a Au surface (Figure 5B), as well as on a Si surface (Figure 5C).
Of key importance with this micro-masonry for Au thin film assembly is that in the absence of any adhesive layer, the transfer printed Au films exhibit electrical conductance with the receiver substrate. While it is difficult to achieve strong mechanical bonding between transfer printed Au films and a receiver Au surface, components are held in place through van der Waal&#8217;s force and exhibit great electrical conductance without any further processing (Figure 5B)9.
Conversely, heterogeneous integration of Au thin films with a Si surface is also achieved through transfer printing and rapid thermal annealing at approximately Si-Au eutectic temperature. Through the annealing process, contact resistance at the Si-Au interface is significantly reduced similar to that of sputter deposited sample due to Si-Au eutectic bonding. By transmission line measurement (TLM) experiments, this claim has been substantiated (Figure 5C)10.
<img alt="Figure 1" fo:content-width="5in" src="/files/ftp_upload/51974/51974fig1highres.jpg" width="500" /> 
Figure 1.&#160;General process flow of micro-masonry7. As a preparation step, a donor substrate, a stamp, and a receiver substrate are independently prepared. (A) Once all of the different components are arranged, first a microtip stamp is attached to a transparent glass slide placed upside down such that the microtips in the stamp are pointing downwards. After the stamp is securely placed, the donor substrate is located on an x,y-axis stage and the stamp is aligned with inks on the donor substrate through a microscope. (B) Subsequently, the stamp is brought down to the donor substrate and a preload is applied on the stamp, such that all microtips in the stamp are fully collapsed. (C) Afterwards, the stamp is quickly raised and the ink is retrieved and attached to a stamp. (D) In order to print the retrieved ink, the stamp with the ink is cautiously aligned to target area and lowered in such that the ink makes contact with the receiver substrate gently while the tips are partially collapsed. (E) While the ink is in contact with the receiver substrate, the stamp is raised slowly. Due to larger van der Waals interaction at ink-receiver interface than at stamp-ink interface, the ink remains on the receiver substrate. (F) The receiver substrate with the assembled inks is moved to a rapid thermal annealing furnace and annealed at 950 &#176;C for 10 min for Si-Si bonding or at 360 &#176;C for Si-Au bonding for 30 min. The annealing step following the transfer printing step completes the micro-masonry procedure. Reproduced with permission from Keum&#160;et al.7 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51974/51974fig1highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" fo:content-width="5in" src="/files/ftp_upload/51974/51974fig2highres.jpg" width="500" /> 
Figure 2.&#160;Schematic of donor substrate preparation. (A) On a SOI wafer, the device layer is patterned into desired dimensions and geometry. (B) A following HF wet etching process removes the exposed SiO2 box layer except for the regions beneath the patterned Si. (C) The photoresist is spun and patterned to form anchors. (D) Afterwards, the substrate is submerged into HF to etch away the remaining SiO2. After sufficient time in HF, the array of Si square inks is suspended and free standing with only photoresist anchors on the donor substrate. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51974/51974fig2highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" fo:content-width="5in" src="/files/ftp_upload/51974/51974fig3highres.jpg" width="500" /> 
Figure 3.&#160;Schematic of stamp fabrication7. (A) In order to make a mold for microtip stamps, a Si wafer is cleaned and small pyramid shaped micropits are created on the wafer through KOH etching. (B) After the etching is done, the surface of the wafer is cleaned through RCA 2 cleaning process followed by applying and patterning SU8 to form a cavity over the microtips. Subsequently, a monolayer of trichlorosilane is coated on the mold to promote the following PDMS molding/demolding process by dropping 3-5 drops of trichlorosilane into a vacuum jar and placing the wafer and vacuuming the vacuum jar. (C) Once the coating is done, the PDMS precursor is poured and cured in the oven. (D) The cured PDMS is simply peeled off from the mold to complete the mold preparation process for a microtip stamp. Reproduced with permission from Keum&#160;et al.7 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51974/51974fig3highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" fo:content-width="5in" src="/files/ftp_upload/51974/51974fig4highres.jpg" width="500" /> 
Figure 4.&#160;Representative work in Si micro-masonry7. (A) Optical microscope images of ring shape Si inks on a donor substrate, (B) Scanning electron microscope (SEM) image of a micro teapot structure formed by micro-masonry, (C) Illustration of micro-masonry of a silicon photonic surface on four Si rings, (D, E) SEM images of the nanostructures on the photonic surface (D) and the assembled silicon photonic surface on four silicon rings (E). Reproduced with permission from Keum&#160;et al.7 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51974/51974fig4highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" fo:content-width="5in" src="/files/ftp_upload/51974/51974fig5highres.jpg" width="500" /> 
Figure 5.&#160;Representative work in Au micro-masonry8. (A) Optical microscopic view of the prepared donor substrate with Au inks retrieved in top row and ready to be retrieved in bottom row, (B) SEM image of a transfer printed Au film on a patterned Au surface, (C) SEM image of transfer printed Au films on a patterned Si strip. Reproduced with permission from Keum&#160;et al.8 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51974/51974fig5highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Micro-masonry for 3D Additive Micromanufacturing at JoVE.com

Micro-masonry for 3D Additive Micromanufacturing

This paper introduces a 3D additive micromanufacturing strategy (termed &#8216;micro-masonry&#8217;) for the flexible fabrication of microelectromechanical system (MEMS) structures and devices. This approach involves transfer printing-based assembly of micro/nanoscale materials in conjunction with rapid thermal annealing-enabled material bonding techniques.

Transfer printing is a method to transfer solid micro/nanoscale materials (herein called &#8216;inks&#8217;) from a substrate where they are generated to ...

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10.3K 조회수.  University of Illinois at Urbana-Champaign. This paper introduces a 3D additive micromanufacturing strategy (termed ‘micro-masonry’) for the flexible fabrication of microelectromechanical system (MEMS) structures and devices. This approach involves transfer printing-based assembly of micro/nanoscale materials in conjunction with rapid thermal annealing-enabled material bonding techniques.

비디오: Micro-masonry for 3D Additive Micromanufacturing

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

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

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

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

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공학

Scalable Nanohelices for Predictive Studies and Enhanced 3D Visualization

Spring-like materials are ubiquitous in nature and of interest in nanotechnology for energy harvesting, hydrogen storage, and biological sensing applications.&#160; For predictive simulations, it has become increasingly important to be able to model the structure of nanohelices accurately.&#160; To study the effect of local structure on the properties of these complex geometries one must develop realistic models.&#160; To date, software packages are rather limited in creating atomistic helical models.&#160; This work focuses on producing atomistic models of silica glass (SiO2) nanoribbons and nanosprings for molecular dynamics (MD) simulations. Using an MD model of &#8220;bulk&#8221; silica glass, two computational procedures to precisely create the shape of nanoribbons and nanosprings are presented.&#160; The first method employs the AWK programming language and open-source software to effectively carve various shapes of silica nanoribbons from the initial bulk model, using desired dimensions and parametric equations to define a helix.&#160; With this method, accurate atomistic silica nanoribbons can be generated for a range of pitch values and dimensions.&#160; The second method involves a more robust code which allows flexibility in modeling nanohelical structures.&#160; This approach utilizes a C++ code particularly written to implement pre-screening methods as well as the mathematical equations for a helix, resulting in greater precision and efficiency when creating nanospring models.&#160; Using these codes, well-defined and scalable nanoribbons and nanosprings suited for atomistic simulations can be effectively created.&#160; An added value in both open-source codes is that they can be adapted to reproduce different helical structures, independent of material.&#160; In addition, a MATLAB graphical user interface (GUI) is used to enhance learning through visualization and interaction for a general user with the atomistic helical structures.&#160; One application of these methods is the recent study of nanohelices via MD simulations for mechanical energy harvesting purposes.

Accurate modeling of nanohelical structures is important for predictive simulation studies leading to novel nanotechnology applications.&#160; Currently, software packages and codes are limited in creating atomistic helical models.&#160; We present two procedures designed to create atomistic nanohelical models for simulations, and a graphical interface to enhance research through visualization.

예측 연구 확장 Nanohelices 향상된 3D 시각화

Spring-like materials are ubiquitous in nature and of interest in nanotechnology for energy harvesting, hydrogen storage, and biological sensing ...

Novel 3D/VR Interactive Environment for MD Simulations, Visualization and Analysis

The increasing development of computing (hardware and software) in the last decades has impacted scientific research in many fields including materials science, biology, chemistry and physics among many others. A new computational system for the accurate and fast simulation and 3D/VR visualization of nanostructures is presented here, using the open-source molecular dynamics (MD) computer program LAMMPS. This alternative computational method uses modern graphics processors, NVIDIA CUDA technology and specialized scientific codes to overcome processing speed barriers common to traditional computing methods. In conjunction with a virtual reality system used to model materials, this enhancement allows the addition of accelerated MD simulation capability. The motivation is to provide a novel research environment which simultaneously allows visualization, simulation, modeling and analysis. The research goal is to investigate the structure and properties of inorganic nanostructures (e.g., silica glass nanosprings) under different conditions using this innovative computational system. The work presented outlines a description of the 3D/VR Visualization System and basic components, an overview of important considerations such as the physical environment, details on the setup and use of the novel system, a general procedure for the accelerated MD enhancement, technical information, and relevant remarks. The impact of this work is the creation of a unique computational system combining nanoscale materials simulation, visualization and interactivity in a virtual environment, which is both a research and teaching instrument at UC Merced.

A new computational system featuring GPU-accelerated molecular dynamics simulation and 3D/VR visualization, analysis and manipulation of nanostructures has been implemented, representing a novel approach to advance materials research and promote innovative investigation and alternative methods to learn about material structures with dimensions invisible to the human eye.

소설 3D / MD 시뮬레이션, 시각화 및 분석을위한 VR 대화 형 환경

The increasing development of computing (hardware and software) in the last decades has impacted scientific research in many fields including materials ...

Development of a 3D Graphene Electrode Dielectrophoretic Device

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The protocol details the procedures to construct a versatile, reusable, multiple layer, laminated dielectrophoresis chamber. Specifically, six layers of 50 &#181;m x&#160;0.7 cm x&#160;2 cm graphene paper and five layers of double sided tape were alternately stacked together, then clamped to a glass slide. Then a 700 &#956;m diameter micro-well was drilled through the laminated structure using a computer-controlled micro drilling machine. Insulating properties of the tape layer between adjacent graphene layers were assured by resistance tests. Silver conductive epoxy connected alternate layers of graphene paper and formed stable connections between the graphene paper and external copper wire electrodes. The finished device was then clamped and sealed to a glass slide. The electric field gradient was modeled within the multi-layer device. Dielectrophoretic behaviors of 6 &#956;m polystyrene beads were demonstrated in the 1 mm deep micro-well, with medium conductivities ranging from 0.0001 S/m to 1.3 S/m, and applied signal frequencies from 100 Hz to 10 MHz. Negative dielectrophoretic responses were observed in three dimensions over most of the conductivity-frequency space and cross-over frequency values are consistent with previously reported literature values. The device did not prevent AC electroosmosis and electrothermal flows, which occurred in the low and high frequency regions, respectively. The graphene paper utilized in this device is versatile and could subsequently function as a biosensor after dielectrophoretic characterizations are complete.

A microdevice with high throughput potential is used to demonstrate three-dimensional (3D) dielectrophoresis (DEP) with novel materials. Graphene nanoplatelet paper and double sided tape were alternately stacked; a 700 &#956;m micro-well was drilled transverse to the layers. DEP behavior of polystyrene beads was demonstrated in the micro-well.

3D 그래 핀 전극 유전 영동 장치의 개발

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The ...

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.

개별 나노 입자의 3D 원소 매핑에 대한 에너지 분산 X 선 단층 촬영

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

Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing technology is used to fabricate particles with slender arms connected at a common center. Shapes explored are crosses (two perpendicular rods), jacks (three perpendicular rods), triads (three rods in triangular planar symmetry), and tetrads (four arms in tetrahedral symmetry). Methods for producing on the order of 10,000 fluorescently dyed particles are described. Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four synchronized videos of their motion in a turbulent flow between oscillating grids with R&#955; = 91. In this relatively low-Reynolds number flow, the advected particles are small enough that they approximate ellipsoidal tracer particles. We present results of time-resolved 3D trajectories of position and orientation of the particles as well as measurements of their rotation rates.

We use 3D printing to fabricate anisotropic particles in the shapes of jacks, crosses, tetrads, and triads, whose alignments and rotations in turbulent fluid flow can be measured from multiple simultaneous video images.

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing ...

3D Printing of Biomolecular Models for Research and Pedagogy

The construction of physical three-dimensional (3D) models of biomolecules can uniquely contribute to the study of the structure-function relationship. 3D structures are most often perceived using the two-dimensional and exclusively visual medium of the computer screen. Converting digital 3D molecular data into real objects enables information to be perceived through an expanded range of human senses, including direct stereoscopic vision, touch, and interaction. Such tangible models facilitate new insights, enable hypothesis testing, and serve as psychological or sensory anchors for conceptual information about the functions of biomolecules. Recent advances in consumer 3D printing technology enable, for the first time, the cost-effective fabrication of high-quality and scientifically accurate models of biomolecules in a variety of molecular representations. However, the optimization of the virtual model and its printing parameters is difficult and time consuming without detailed guidance. Here, we provide a guide on the digital design and physical fabrication of biomolecule models for research and pedagogy using open source or low-cost software and low-cost 3D printers that use fused filament fabrication technology.

Physical models of biomolecules can facilitate an understanding of their structure-function for the researcher, aid in communication between researchers, and serve as an educational tool in pedagogical endeavors. Here, we provide detailed guidance for the 3D printing of accurate models of biomolecules using fused filament fabrication desktop 3D printers.

연구 및 교육학에 대한 생명 모델의 3D 인쇄

The construction of physical three-dimensional (3D) models of biomolecules can uniquely contribute to the study of the structure-function relationship. 3D ...

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

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

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

유기 광전자 소자에 대 한 3D 인쇄 챔버 저하 테스트

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

A Soft Tooling Process Chain for Injection Molding of a 3D Component with Micro Pillars

The purpose of this paper is to present the method of a soft tooling process chain employing Additive Manufacturing (AM) for fabrication of injection molding inserts with micro surface features. The Soft Tooling inserts are manufactured by Digital Light Processing (vat photo polymerization) using a photopolymer that can withstand relatively high temperaturea. The part manufactured here has four tines with an angle of 60&#176;. Micro pillars (&#216;200 &#181;m, aspect ratio of 1) are arranged on the surfaces by two rows. Polyethylene (PE) injection molding with the soft tooling inserts is used to fabricate the final parts. This method demonstrates that it is feasible to obtain injection-molded parts with microstructures on complex geometry by additive manufactured inserts. The machining time and cost is reduced significantly compared to conventional tooling processes based on computer numerical control (CNC) machining. The dimensions of the micro features are influenced by the applied additive manufacturing process. The lifetime of the inserts determines that this process is more suitable for pilot production. The precision of the inserts production is limited by the additive manufacturing process as well.

A protocol for fabricating injection molding inserts for complex geometry with micro features on surfaces employing Additive Manufacturing (AM) is presented.

마이크로 3D 부품의 사출 성형에 대 한 부드러운 금형 프로세스 체인 기둥

The purpose of this paper is to present the method of a soft tooling process chain employing Additive Manufacturing (AM) for fabrication of injection ...

Multi-material Ceramic-Based Components &#8211; Additive Manufacturing of Black-and-white Zirconia Components by Thermoplastic 3D-Printing (CerAM - T3DP)

To combine the benefits of Additive Manufacturing (AM) with the benefits of Functionally Graded Materials (FGM) to ceramic-based 4D components (three dimensions for the geometry and one degree of freedom concerning the material properties at each position) the Thermoplastic 3D-Printing (CerAM -&#160;T3DP) was developed. It is a direct AM technology which allows the AM of multi-material components. To demonstrate the advantages of this technology black-and-white zirconia components were additively manufactured and co-sintered defect-free.
Two different pairs of black and white zirconia powders were used to prepare different thermoplastic suspensions. Appropriate dispensing parameters were investigated to manufacture single-material test components and adjusted for the additive manufacturing of multi-color zirconia components.

Here we describe a protocol for additively manufacturing black-and-white zirconia components by Thermoplastic 3D-Printing (CerAM -&#160;T3DP) and co-sintering defect-free.

멀티 소재 세라믹 기반 구성 요소-열가 소성 3D 인쇄 (CerAM-T3DP)에 의해 흑백 지 르 코니 아 부품의 제조 첨가물

To combine the benefits of Additive Manufacturing (AM) with the benefits of Functionally Graded Materials (FGM) to ceramic-based 4D components (three ...