https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(01)05321-1.pdf

Antibiotic resistance of bacteria in biofilms

1. Introduction 2. Theoretical foundations 3. Propagation and focusing of optical fields 4. Spatial resolution and position accuracy 5. Nanoscale optical microscopy 6. Near-field optical probes 7. Probe-sample distance control 8. Light emission and optical interaction in nanoscale environments 9. Quantum emitters 10. Dipole emission near planar interfaces 11. Photonic crystals and resonators 12. Surface plasmons 13. Forces in confined fields 14. Fluctuation-induced phenomena 15. Theoretical methods in nano-optics Appendices Index.

/pdf/principles-of-nano-optics-1hz998yqo8.pdf

Principles of nano-optics

Nanoelectromechanical systems were fabricated from single- and multilayer graphene sheets by mechanically exfoliating thin sheets from graphite over trenches in silicon oxide. Vibrations with fundamental resonant frequencies in the megahertz range are actuated either optically or electrically and detected optically by interferometry. We demonstrate room-temperature charge sensitivities down to 8 × 10 –4 electrons per root hertz. The thinnest resonator consists of a single suspended layer of atoms and represents the ultimate limit of two-dimensional nanoelectromechanical systems.

https://science.sciencemag.org/content/sci/315/5811/490.full.pdf

Electromechanical Resonators from Graphene Sheets

The Young's modulus (E) of a material is a key parameter for mechanical engineering design. Silicon, the most common single material used in microelectromechanical systems (MEMS), is an anisotropic crystalline material whose material properties depend on orientation relative to the crystal lattice. This fact means that the correct value of E for analyzing two different designs in silicon may differ by up to 45%. However, perhaps, because of the perceived complexity of the subject, many researchers oversimplify silicon elastic behavior and use inaccurate values for design and analysis. This paper presents the best known elasticity data for silicon, both in depth and in a summary form, so that it may be readily accessible to MEMS designers.

/pdf/what-is-the-young-s-modulus-of-silicon-1dse7n0e06.pdf

What is the Young's Modulus of Silicon?

The present invention provides stretchable, and optionally printable, semiconductors and electronic circuits capable of providing good performance when stretched, compressed, flexed or otherwise deformed. Stretchable semiconductors and electronic circuits of the present invention preferred for some applications are flexible, in addition to being stretchable, and thus are capable of significant elongation, flexing, bending or other deformation along one or more axes. Further, stretchable semiconductors and electronic circuits of the present invention may be adapted to a wide range of device configurations to provide fully flexible electronic and optoelectronic devices.

http://science.sciencemag.org/content/sci/311/5758/208.full.pdf

Stretchable form of single crystal silicon for high performance electronics on rubber substrates

Ultrathin resonant cantilevers are promising for ultrasensitive detection. A technique is developed for high-yield fabrication of single-crystalline-silicon cantilevers as thin as 12 nm. The formed cantilever resonators are characterized by resonance testing in high vacuum. Significant specimen size effect on Young’s modulus of ultrathin (12–170 nm) silicon is detected. The Young’s modulus decreases monotonously as the cantilevers become thinner. The size effect is consistent with the published simulation results of direct-atomistic model, in which surface effects are taken into consideration.

Ultrathin single-crystalline-silicon cantilever resonators: Fabrication technology and significant specimen size effect on Young’s modulus

Discusses four kinds of mechanical energy losses in ultrathin micro-cantilevers of 60 nm, 170 nm, and 500 nm in thickness: thermoelastic loss, air damping, support loss, and surface loss. For the cantilevers with thickness H 10 /spl mu/m, thermoelastic loss is negligible. But it becomes significant when the beam thickness H>500 nm and the length L 30 /spl mu/m, the Q factors of the cantilevers are proportional to their thickness, i.e., surface loss dominates the mechanical behavior. Annealing the cantilevers of 170 nm thickness at 1000/spl deg/C for 30 s under an ultrahigh vacuum (UHV) condition results in an over one order-of-magnitude increase of the Q factor, up to about 2.5/spl times/10/sup 5/ for cantilevers of 30-90 /spl mu/m in length.

Energy dissipation in submicrometer thick single-crystal silicon cantilevers

Surface effects in ultrathin single-crystal silicon cantilevers of 170 nm thickness, which are optically actuated mainly by the light pressure effect, are investigated under ultrahigh vacuum (UHV) condition. Annealing the cantilevers at 1000 °C for 30 s in UHV results in an over 1 order of magnitude increase of the quality factor (Q factor), up to about 2.5×105 for cantilevers of 30–90 μm in length. The improvement of Q factor was found to be associated with the deoxidization of the surface, as determined by x-ray photoelectron spectroscopy. These results suggest that the surface effects in the ultrathin cantilevers dominate their mechanical behavior. With the promising mechanical behavior, the cantilever can be easily actuated by a laser beam (beam size: about 300×100 μm2) with power down to less than 40 μW at a wavelength of 680 nm, corresponding to 480 nW, i.e., 1.64×1012 photons/s, irradiated on the cantilever surface (60×6 μm2). This provides a rather simple way to operate the ultrathin cantilevers dynamically in UHV. Atomic scale force resolution (4.8×10−17 N) at 300 K is also expected with these cantilevers.

Surface effects and high quality factors in ultrathin single-crystal silicon cantilevers

Ultrathin single-crystalline silicon cantilevers with a thickness of 170 nm as a resonating sensor are applied to mass sensing. The hydrogen storage capacity of a small amount of carbon nanotubes (CNTs), which were mounted on an ultrathin resonator by a manipulator, is measured from the resonant frequency change. The resonator is annealed in ultrahigh vacuum to clean the surface and increase the quality factor, and exposed to oxygen gas to oxidize the surface for long-term stability. The resonator can be electrostatically actuated, and the vibration is measured by a laser Doppler vibrometer in ultrahigh vacuum. The mass of the CNTs is determined by the difference of resonant frequencies before and after mounting the CNTs, and the hydrogen storage capacity is determined from the frequency change after exposure to high-pressure hydrogen as well. The obtained hydrogen storage capacitance is 1.6%–6.0%. The available mass resolution and the achieved stability of the resonance of the 170-nm-thick resonator are below 10−18 g and 5 Hz/days, respectively.

Mass sensing of adsorbed molecules in sub-picogram sample with ultrathin silicon resonator

Mechanical characteristics of a single crystal silicon ultrathin cantilever and their dependence on the geometry was investigated in this paper. The cantilevers with thickness 60 and 170 nm and length 5–120 μm have been fabricated from 〈100〉-oriented SIMOX wafer. Preliminary results show that the longer cantilevers (L>30 μm) have higher mechanical quality factor, Q (>104) than the shorter ones (L<30 μm), since the shorter one is more susceptible to the energy loss, i.e., support loss and surface loss (oxide layer). Furthermore, multimode resonance of the longer cantilever was observable within the measurable range, and all of them have the Q factor higher than 104. By using the high resonance mode, these cantilevers are theoretically capable of detecting the force as small as 2×10−17 N. In addition, the atomic scale mass resolution (1.4×10−22 g) is also expected by these cantilevers if it is used for sensing the mass load. Using the dynamic detection method, water vapor adsorption was detected, and the mass resolution of the cantilever is roughly estimated to be 2.9×10−17 g.

Takahito Ono

Papers

Ultrathin single-crystalline-silicon cantilever resonators: Fabrication technology and significant specimen size effect on Young’s modulus

Energy dissipation in submicrometer thick single-crystal silicon cantilevers

Surface effects and high quality factors in ultrathin single-crystal silicon cantilevers

Mass sensing of adsorbed molecules in sub-picogram sample with ultrathin silicon resonator

Mechanical behavior of ultrathin microcantilever