Electrical power for distributed, wireless sensors may be harvested from vibrations in the
ambient through the use of electromechanical transducers. To be most useful, the
electromechanical transducer should maximize the harvested power by matching its
resonant frequency to the strongest vibration amplitude in the source’s vibration
spectrum. This paper introduces a new frequency tunable mechanism wherein the
deformation of the piezoelectric elements is primarily in-plane extension, and
bending effects may be neglected. The extensional mode resonator (XMR) is formed
by suspending a seismic mass with two piezoelectric sheets. The mechanism is
made frequency tunable by an adjustable link that symmetrically pre-tensions
both piezoelectric sheets. A prototype XMR has been built and tested that has
demonstrated adjustable and repeatable resonant frequency variation from 80
to 235 Hz. The electrical power generated by the XMR is also insensitive to the
driving frequency, when the resonant frequency is matched to the driving frequency.
Nanoarchitectural control of matter is crucial for next-generation technologies. DNA origami templates are harnessed to accurately position single molecules; however, direct single molecule evidence is lacking regarding how well DNA origami can control the orientation of such molecules in three-dimensional space, as well as the factors affecting control. Here, we present two strategies for controlling the polar (θ) and in-plane azimuthal (ϕ) angular orientations of cyanine Cy5 single molecules tethered on rationally-designed DNA origami templates that are physically adsorbed (physisorbed) on glass substrates. By using dipolar imaging to evaluate Cy5′s orientation and super-resolution microscopy, the absolute spatial orientation of Cy5 is calculated relative to the DNA template. The sequence-dependent partial intercalation of Cy5 is discovered and supported theoretically using density functional theory and molecular dynamics simulations, and it is harnessed as our first strategy to achieve θ control for a full revolution with dispersion as small as ±4.5°. In our second strategy, ϕ control is achieved by mechanically stretching the Cy5 from its two tethers, being the dispersion ±10.3° for full stretching. These results can in principle be applied to any single molecule, expanding in this way the capabilities of DNA as a functional templating material for single-molecule orientation control. The experimental and modeling insights provided herein will help engineer similar self-assembling molecular systems based on polymers, such as RNA and proteins.
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