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Metadata of the Chapter That Will Be Visualized Online Metadata of the chapter that will be visualized online Chapter Title Diamondoid Mechanosynthesis for Tip-Based Nanofabrication Chapter Sub-Title Chapter CopyRight - Year Springer Science+Business Media, LLC 2011 (This will be the copyright line in the final PDF) Book Name Tip-Based Nanofabrication Corresponding Author Family Name Freitas Particle Given Name Robert A. Suffix Jr Division Organization Institute for Molecular Manufacturing Address Palo Alto, CA, 94301, USA Email [email protected] Abstract Diamond mechanosynthesis (DMS), or molecular positional fabrication, is the formation of covalent chemical bonds using precisely applied mechanical forces to build nanoscale diamondoid structures via manipulation of positionally controlled tooltips, most likely in a UHV working environment. DMS may be automated via computer control, enabling programmable molecular positional fabrication. The Nanofactory Collaboration is coordinating a combined experimental and theoretical effort involving direct collaborations among dozens of researchers at institutions in multiple countries to explore the feasibility of positionally controlled mechanosynthesis of diamondoid structures using simple molecular feedstocks, the first step along a direct pathway to developing working nanofactories. Keywords (separated by '-') Carbon placement - Diamond - Diamondoid - DMS - Hydrogen abstraction - Hydrogen donation - Mechanosynthesis - Minimal toolset - Molecular manufacturing - Nanofactory - Nanofactory Collaboration - Nanopart - Positional assembly - Positional fabrication - tooltips SPB-217859 Chapter ID 11 April 11, 2011 Time: 04:18pm Proof 1 01 Chapter 11 02 Diamondoid Mechanosynthesis for Tip-Based 03 04 Nanofabrication 05 06 07 Robert A. Freitas Jr. 08 09 10 Abstract Diamond mechanosynthesis (DMS), or molecular positional fabrication, 11 is the formation of covalent chemical bonds using precisely applied mechanical 12 forces to build nanoscale diamondoid structures via manipulation of positionally 13 controlled tooltips, most likely in a UHV working environment. DMS may be 14 automated via computer control, enabling programmable molecular positional fab- 15 rication. The Nanofactory Collaboration is coordinating a combined experimental 16 and theoretical effort involving direct collaborations among dozens of researchers at 17 institutions in multiple countries to explore the feasibility of positionally controlled 18 mechanosynthesis of diamondoid structures using simple molecular feedstocks, the 19 first step along a direct pathway to developing working nanofactories. 20 21 Keywords Carbon placement · Diamond · Diamondoid · DMS · Hydrogen 22 abstraction · Hydrogen donation · Mechanosynthesis · Minimal toolset · Molecular 23 manufacturing · Nanofactory · Nanofactory Collaboration · Nanopart · Positional 24 assembly · Positional fabrication · tooltips 25 26 27 Abbreviations 28 AFM Atomic force microscope 29 CPU Central processing unit 30 CVD Chemical vapor deposition 31 DFT Density functional theory 32 DMS Diamond mechanosynthesis 33 DNA Deoxyribonucleic acid 34 MEMS Microelectromechanical systems 35 NIST National Institute of Standards and Technology (U.S.) 36 NMAB National Materials Advisory Board (U.S.) 37 NNI National Nanotechnology Initiative (U.S.) 38 NRC National Research Council of the National Academies (U.S.) 39 ONR Office of Naval Research (U.S.) 40 SEM Scanning electron microscopy 41 42 43 R.A. Freitas (B) 44 Institute for Molecular Manufacturing, Palo Alto, CA 94301, USA 45 e-mail: [email protected] PROOF A.A. Tseng (ed.), Tip-Based Nanofabrication, DOI 10.1007/978-1-4419-9899-6_11, C Springer Science+Business Media, LLC 2011 SPB-217859 Chapter ID 11 April 11, 2011 Time: 04:18pm Proof 1 R.A. Freitas 46 SPM Scanning probe microscope 47 UHV Ultra-high vacuum 48 49 50 51 11.1 Positional Diamondoid Molecular Manufacturing 52 53 Complex molecular machine systems [1–6], including microscale robotic mecha- 54 nisms comprised of thousands or millions of nanoscale mechanical components 55 such as gears, motors, and computer elements, probably cannot be manufactured 56 using the conventional techniques of self-assembly. As noted in the final report [7] 57 of the 2006 Congressionally-mandated review of the U.S. National Nanotechnology 58 Initiative by the National Research Council (NRC) of the National Academies and 59 the National Materials Advisory Board (NMAB): “For the manufacture of more 60 sophisticated materials and devices, including complex objects produced in large 61 quantities, it is unlikely that simple self-assembly processes will yield the desired 62 results. The reason is that the probability of an error occurring at some point in the 63 process will increase with the complexity of the system and the number of parts that 64 must interoperate.” Error detection and correction requires a minimum level of com- 65 plexity that cannot easily be achieved via thermodynamically-driven self-assembly 66 processes. 67 The opposite of self-assembly processes is positionally controlled processes, in 68 which the positions and trajectories of all components of intermediate and final 69 product objects are controlled at every moment during fabrication and assembly. 70 Positional processes should allow more complex products to be built with high 71 quality and should enable rapid prototyping during product development. Pure posi- 72 tional assembly is the norm in conventional macroscale manufacturing (e.g., cars, 73 appliances, houses) but is only relatively recently [8, 9] starting to be seriously 74 investigated experimentally for nanoscale manufacturing. Of course, we already 75 know that positional fabrication can work in the nanoscale realm. This is demon- 76 strated in the biological world by ribosomes, which positionally assemble proteins in 77 living cells by following a sequence of digitally encoded instructions (even though 78 ribosomes themselves are self-assembled). Lacking this positional fabrication of 79 proteins controlled by DNA-based software, large, complex, digitally-specified 80 organisms would probably not be possible and biology as we know it would not 81 exist. Guided self-assembly – another hybrid approach combining self-assembly 82 and positional assembly – is also being investigated experimentally [10, 11]. 83 The most important materials for positional assembly may be the rigid cova- 84 lent or “diamondoid” solids, since these could potentially be used to build the 85 most reliable and complex nanoscale machinery. Preliminary theoretical studies 86 have suggested great promise for these materials in molecular manufacturing. The 87 NMAB/NRC Review Committee recommended [7] that experimental work aimed at 88 establishing the technical feasibility of positional molecular manufacturing should 89 be pursued and supported: “Experimentation leading to demonstrations supplying 90 ground truth for abstractUNCORRECTED models is appropriate to better characterize PROOF the potential for SPB-217859 Chapter ID 11 April 11, 2011 Time: 04:18pm Proof 1 11 Diamondoid Mechanosynthesis for Tip-Based Nanofabrication 91 use of bottom-up or molecular manufacturing systems that utilize processes more 92 complex than self-assembly.” Making complex nanorobotic systems requires man- 93 ufacturing techniques that can build a molecular structure by positional assembly 94 [9, 12]. This will involve picking and placing molecular parts one by one, mov- 95 ing them along controlled trajectories much like the robot arms that manufacture 96 cars on automobile assembly lines. The procedure is then repeated over and over 97 with all the different parts until the final product is fully assembled inside a desktop 98 nanofactory. 99 Technologies required for the atomically precise fabrication of diamondoid 100 nanorobots in macroscale quantities at low cost requires the development of a new 101 nanoscale manufacturing technology called positional diamondoid molecular manu- 102 facturing, enabling diamondoid nanofactories. Achieving this new technology over 103 the next 1–3 decades will require the significant further development of multiple 104 closely related technical capabilities: diamondoid mechanosynthesis, programmable 105 positional assembly, massively parallel positional fabrication and assembly, and 106 nanomechanical design. 107 108 109 11.2 Diamondoid Mechanosynthesis (DMS) 110 111 Mechanosynthesis, or molecular positional fabrication, is the formation of cova- 112 lent chemical bonds using precisely applied mechanical forces to build atomi- 113 cally precise structures. Mechanosynthesis will be most efficient when automated 114 via computer control, enabling programmable molecular positional fabrication of 115 nanostructures of significant size. Atomically precise fabrication involves holding 116 feedstock atoms or molecules, and separately a growing nanoscale workpiece, in 117 the proper relative positions and orientations so that when they touch they will 118 chemically bond in the desired manner. In this process, a mechanosynthetic tool 119 is brought up to the surface of a workpiece. One or more transfer atoms are added 120 to (Fig. 11.1), or removed from, the workpiece by the tool. Then the tool is with- 121 drawn and recharged. This process is repeated until the workpiece (e.g., a growing 122 nanopart) is completely fabricated to atomic precision with each atom in exactly 123 the right place. The transfer atoms are under positional control at all times to pre- 124 vent unwanted side reactions from occurring. Side reactions
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