Research ArticleMATERIALS SCIENCE

Mechanically active materials in three-dimensional mesostructures

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Science Advances  14 Sep 2018:
Vol. 4, no. 9, eaat8313
DOI: 10.1126/sciadv.aat8313
  • Fig. 1 Schematic illustrations, optical images, SEM images, and finite element modeling results for a representative 3D mesostructure with five independently addressable PZT microactuators.

    (A) Schematic illustration of the 2D architecture of the system. (B) Schematic illustration of the 3D system after assembly by controlled biaxial compressive buckling. (C) Exploded view of the layout. (D) Optical images (top and perspective views) of the 3D architecture. (E) SEM images (top and perspective views). The false color of the top-view image highlights the electrodes (gold) and PZT actuators (blue). (F) Results of finite element modeling, with color representation for the magnitude of the strain. Only small strains appear in the PZT microactuators. Scale bars, 500 μm.

  • Fig. 2 Demonstration of diverse 3D architectures with integrated PZT microactuators.

    (A) “Bridge” structure with two PZT microactuators. (B) “Fly” structure with a pair of actuators on the wings. (C) “Tilted pyramid truss” structure with three actuators. (D) “Four-leg table” structure with an actuator on each leg. (E) “Rotated table” structure with an actuator on each leg. (F) “Rotated table” with a central hole on top and four actuators. (G) “Double-floor rotated table” structure that consists of a large rotated table and a small one on the top, with four actuators. (H) “Double-floor rotated table” structure with five actuators (the additional one on top). Each panel includes a side and a top view. The yellow and blue regions correspond to the electrodes and PZT microactuators, respectively. Scale bars, 500 μm. The contour plots show results of FEA modeling for the maximum principal strain in the electrodes and PZT microactuators.

  • Fig. 3 Vibratory behavior of 3D mesostructures excited by PZT microactuators.

    (A) Bridge structure with two actuators and the experimental amplitude-frequency responses for excitation with different voltages applied to the PZT microactuators. (B) Normalized amplitude-frequency curves. (C) Finite element modeling of the vibration. (D and E) Table structure with an actuator integrated on each leg and its amplitude-frequency responses for left-right and back-front vibrational modes. (F) Finite element modeling of the resonant modes of the table structure. (G) Vibratory responses of the fly structure. (H) Flapping mode, selectively excited by integrated actuators. (I and J) Tilted-pyramid truss dynamic responses and corresponding resonant modes. (K) A double-floor rotated table with four actuators and its amplitude-frequency responses. (L) The resonant modes of the double-floor rotated table. Scale bars, 500 μm.

  • Fig. 4 Strategically optimized 3D mesostructures provide decoupled modes for separate determinations of fluidic density and viscosity.

    (A) Vibratory responses of the double-floor rotated table when immersed in water-glycerol mixtures. (B) Change of resonant frequencies as a function of volume fraction of glycerol. (C) Theoretical model for the calculation of fluidic properties and its FEA validation. In (C) Embedded Image. (D and E) Decoupled sensitivities of the two resonant modes of the double-floor structure to fluidic properties. (F and G) Coupled sensitivities of a cantilever structure to fluidic properties. (H and I) Calculated viscosity and density as inferred from theoretical models. (J) Measured amplitude-frequency responses at different temperatures. (K) Change of resonant frequency as a function of temperature. (L) Relative change of resonant frequency as a function of temperature. (M) Calculated viscosity at various temperatures. exp., experiment.

  • Fig. 5 Measurements of biological, complex, and time-variant fluids.

    (A to D) Measured vibratory responses of the double-floor rotated table in PBS, cell-culturing media, porcine serum, and porcine plasma, respectively, including the calculated viscosities and comparisons to values measured by a commercial rheometer. (E) Vibrational response in a complex fluid (Carbopol microgel particle suspension in water). (F and G) Change of resonant frequency of a bridge-shaped device due to the evaporation of a 5-μl droplet of water (F) and blood (G) under the device.

  • Fig. 6 Conformal integration of 3D devices onto biomedical devices.

    (A) A cardiovascular stent with three devices corresponding to tubes 1, 2, and 3, respectively. Scale bars, 1 cm. (B) The device deforms along with the stent while maintaining robust adhesion. Scale bar, 1 cm. (C) A flexible catheter with a device that is bent to different curvatures. The device is at the location of the dashed line. Scale bars, 2.5 cm. (D) Magnified view of a device integrated on a catheter. Scale bar, 5 mm. (E) A balloon catheter with a device, in an inflated (left) and deflated (right) configuration. Scale bars, 1 cm. (F) Magnified view of a device on the balloon. Scale bar, 5 mm.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/9/eaat8313/DC1

    Note S1. FEA and CFD

    Note S2. Validation of the scaling law

    Note S3. Deriving the scaling law (Eq. 2)

    Note S4. Solution to the fluid properties and accuracy analysis

    Note S5. Measurement of fluidic viscosity by commercial rheometer

    Note S6. Stretching and releasing substrates

    Fig. S1. Schematic illustration of procedures for fabricating PZT nanomembrane inks.

    Fig. S2. Schematic illustration of the transfer printing of PZT actuators and the fabrication of 2D precursors.

    Fig. S3. Transfer printing of the 2D precursors and the assembly process by compressive bulking.

    Fig. S4. Parameter study on the maximum principal strain in PZT and electrode.

    Fig. S5. Perspective views of the 3D architectures with integrated PZT nanomembranes.

    Fig. S6. Optical images of the perspective and top views of the 3D architectures with integrated PZT nanomembranes.

    Fig. S7. 2D precursors of the structures in Fig. 2.

    Fig. S8. Distribution of the maximum principal strain in SU-8 for the structures in Fig. 2.

    Fig. S9. Illustration of the PZT actuation for the vibration modes shown in Fig. 3 and fig. S10.

    Fig. S10. Dynamics of 3D architectures with multiple modes excited by PZT nanomembranes.

    Fig. S11. Dependence of the resonant frequency on the geometry/material parameters.

    Fig. S12. Dynamic response in fluids.

    Fig. S13. Validation of the scaling law (Eq. 1).

    Fig. S14. Validation of the scaling law (Eq. 2) in the case when the Reynolds number is far larger than 1.

    Fig. S15. Geometrical parameters and the vibration modes for the cantilever example shown in Fig. 4 (F and G).

    Fig. S16. Accuracy of the measured fluid density and viscosity.

    Fig. S17. Measured density of the water-glycerol mixture with 66.7% glycerol volume fraction when the temperature ranges from 24° to 42.9°C.

    Fig. S18. Apparatus for the measurements of vibrational modes in fluids at various temperatures.

    Fig. S19. Shear rate dependence of the viscosities of the biofluids measured by the commercial rheometer, m-VROC viscometer.

    Fig. S20. Schematic illustration and dimension of the fluidic channel of the commercial rheometer, m-VROC viscometer.

    Movie S1. Assembly of 3D active mesostructures.

    Movie S2. Vibrational modes.

  • Supplementary Materials

    The PDF file includes:

    • Note S1. FEA and CFD
    • Note S2. Validation of the scaling law
    • Note S3. Deriving the scaling law (Eq. 2)
    • Note S4. Solution to the fluid properties and accuracy analysis
    • Note S5. Measurement of fluidic viscosity by commercial rheometer
    • Note S6. Stretching and releasing substrates
    • Fig. S1. Schematic illustration of procedures for fabricating PZT nanomembrane inks.
    • Fig. S2. Schematic illustration of the transfer printing of PZT actuators and the fabrication of 2D precursors.
    • Fig. S3. Transfer printing of the 2D precursors and the assembly process by compressive bulking.
    • Fig. S4. Parameter study on the maximum principal strain in PZT and electrode.
    • Fig. S5. Perspective views of the 3D architectures with integrated PZT nanomembranes.
    • Fig. S6. Optical images of the perspective and top views of the 3D architectures with integrated PZT nanomembranes.
    • Fig. S7. 2D precursors of the structures in Fig. 2.
    • Fig. S8. Distribution of the maximum principal strain in SU-8 for the structures in Fig. 2.
    • Fig. S9. Illustration of the PZT actuation for the vibration modes shown in Fig. 3 and fig. S10.
    • Fig. S10. Dynamics of 3D architectures with multiple modes excited by PZT nanomembranes.
    • Fig. S11. Dependence of the resonant frequency on the geometry/material parameters.
    • Fig. S12. Dynamic response in fluids.
    • Fig. S13. Validation of the scaling law (Eq. 1).
    • Fig. S14. Validation of the scaling law (Eq. 2) in the case when the Reynolds number is far larger than 1.
    • Fig. S15. Geometrical parameters and the vibration modes for the cantilever example shown in Fig. 4 (F and G).
    • Fig. S16. Accuracy of the measured fluid density and viscosity.
    • Fig. S17. Measured density of the water-glycerol mixture with 66.7% glycerol volume fraction when the temperature ranges from 24° to 42.9°C.
    • Fig. S18. Apparatus for the measurements of vibrational modes in fluids at various temperatures.
    • Fig. S19. Shear rate dependence of the viscosities of the biofluids measured by the commercial rheometer, m-VROC viscometer.
    • Fig. S20. Schematic illustration and dimension of the fluidic channel of the commercial rheometer, m-VROC viscometer.
    • Legends for movies S1 and S2

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Assembly of 3D active mesostructures.
    • Movie S2 (.mp4 format). Vibrational modes.

    Files in this Data Supplement:

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