Earlier this week, we announced that CRN has prepared a list of thirty essential studies (in the form of questions to be addressed) that must be performed before we can have an adequate understanding of the potential societal impacts of nanotechnology. To begin this iterative process, CRN has supplied provisional answers for each study, with supporting data where available.
Our recommended study #7 reads: "What applicable sensing, manipulation, and fabrication tools exist?"
Development efforts will be aided by the ability to directly interact with the nanoscale, to manipulate nanoscale objects and to sense nanoscale structures. In particular, a combination of sensing and manipulation in the same platform will be very helpful.Subquestion A: What nanometer or angstrom-level sensing modalities exist or can be developed for off-the-shelf use? In particular, can sub-wavelength nanometer-scale optical non-proximal video imaging be developed?
Preliminary answer: Sensing at the nanoscale has been difficult, because traditional optics can't 'see' smaller than a few hundred nanometers. However, a variety of sub-wavelength technologies do exist. For example, two-part fluorescent systems can detect nanometer displacements. Electron microscopes can image down to angstrom levels. Scanning proximal near-field technologies can bypass the diffraction limit. Other scanning technologies can reach atomic resolution (AFM, STM, even MFM). Most interestingly, it appears that near-field effects can be extracted and detected, allowing parallel (video-like) 3D non-proximal imaging of nanometer-scale features. AngstroVision claims to have developed a system that can detect 12x12x4 nm at 1-3 frames per second. NASA has also published theoretical work leading to a sub-wavelength non-proximal imaging system using incoherent light.
Subquestion B: What manipulation technologies exist or can be developed for off-the-shelf use?
Preliminary answer: For positioning: piezo-driven probes; optical tweezers. For gripping: antibodies; recent work on engineering RNA to grip arbitrary shape; perhaps EBD-fabricated tweezers.
Subquestion C: What combinations of sensing and manipulation can be integrated?
Preliminary answer: Piezo probes have been placed inside a SEM and integrated with EBD in Denmark. AngstroVision claims their system will work in a shirtsleeve environment; possibly in conjunction with optical tweezers.
Subquestion D: What environments can be supported by the various techniques and combinations? High temperature, room temperature, low/cryogenic temperature? High vacuum? Solvated? Micro environments (e.g. droplets)?
Preliminary answer: Detailed engineering studies are needed here.Subquestion E: What nano-fabrication technologies exist or can be developed for off-the-shelf use? (Special attention should be given to technologies that produce rapid and low-cost results.)
Preliminary answer: Direct-write lithography: laser, e-beam, dip-pen nanolithography (DPN). Gel deposition, possibly with glass precursor coating/baking for further miniaturization. 3D Inkjet? Chemistry plus self-assembly: a very large field with lots of possibilities. Nanotube welding. Electron beam deposition (EBD). Et cetera.
Subquestion F: What are compatible combinations of nano-fabrication and real-time sensing? What nano-fabrication technologies are well enough modeled for reliable CAD-to-product workflow?
Preliminary answer: EBD and nanotube welding with SEM. Chemistry with fluorescence and maybe with non-proximal near-field imaging as described above. DPN with scanning tactile probe. Unknown what technologies are compatible with CAD-to-product; to some extent this depends on the required product characteristics. But note that a major DPN manufacturer is now selling text-writing software.
Subquestion G: What handling technologies exist for moving samples between environments and/or locations efficiently?
Preliminary answer: Unknown.
Subquestion H: Which of these technologies is compatible with automation and/or high throughput?
Preliminary answer: Unknown. Probably most are compatible with automation. Chemistry plus self-assembly is generally compatible with high throughput.
Provisional conclusion: Many relevant fabrication and sensing tools exist off-the-shelf. Single-nanometer optical open-air video imaging is a strong possibility. Chemistry and lithography (bottom-up and top-down) have already met in the middle.
CRN's initial basic findings (preliminary answers and provisional conclusions) for all thirty studies should be verified as rapidly as possible. Because our understanding points to a crisis, a parallel process of conducting the studies is strongly preferred.
We are actively looking for researchers who have an interest in performing or assisting with this work. Please contact CRN Research Director Chris Phoenix if you would like more information or if you have comments on the proposed studies.
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