Abstract: A microelectromechanical (MEMS) interferometer is provided. The MEMS interferometer includes a pair of movable mirrors that are positioned along perpendicular axes, wherein each of the pair of movable mirrors is coupled to a mechanism. The mechanism includes an electrostatic actuator driving a displacement amplification mechanism, and the displacement amplification mechanism driving each of the pair of the movable mirrors. The MEMS interferometer includes a beam splitter that is positioned at an intersection of the perpendicular axes extending through each movable mirror and the beam splitter. The MEMS interferometer also includes a metasurface microbolometer placed in line with the beam splitter to measure an intensity of a recombined beam from the pair of movable mirrors.

Abstract: A microelectromechanical (MEMS) interferometer is provided. The MEMS interferometer includes a pair of movable mirrors that are positioned along perpendicular axes, wherein each of the pair of movable mirrors is coupled to a mechanism. The mechanism includes an electrostatic actuator driving a displacement amplification mechanism, and the displacement amplification mechanism driving each of the pair of the movable mirrors. The MEMS interferometer includes a beam splitter that is positioned at an intersection of the perpendicular axes extending through each movable mirror and the beam splitter. The MEMS interferometer also includes a metasurface microbolometer placed in line with the beam splitter to measure an intensity of a recombined beam from the pair of movable mirrors.

Abstract: A miniature Fourier transform mid-infrared (FT-MIR) spectrometer is provided. The FT-MIR includes a metasurface IR source to emit radiation when heated, a microelectromechanical (MEMS) interferometer, and a metasurface microbolometer to measure an interferogram from the MEMS interferometer, wherein the miniature FT-MIR spectrometer is less than about 20 mm in outer diameter.

Abstract: A miniature Fourier transform mid-infrared (FT-MIR) spectrometer is provided. The FT-MIR includes a metasurface IR source to emit radiation when heated, a microelectromechanical (MEMS) interferometer, and a metasurface microbolometer to measure an interferogram from the MEMS interferometer, wherein the miniature FT-MIR spectrometer is less than about 20 mm in outer diameter.

Abstract: A miniature Fourier transform mid-infrared (FT-MIR) spectrometer is provided. The FT-MIR includes a metasurface IR source to emit radiation when heated, a microelectromechanical (MEMS) interferometer, and a metasurface microbolometer to measure an interferogram from the MEMS interferometer, wherein the miniature FT-MIR spectrometer is less than about 20 mm in outer diameter.

Abstract: This specification describes a leaf cell resonator sensor based on a geometry of Rhodonea conformal contours joined circumferentially in an eight-fold symmetry by central spoke electrode members. The resonator sensor may provide simultaneous and congruent measurement of fluid density and sound speed based on interaction of the leaf cell dynamics with self-formed Helmholtz cavity dilatational response of the fluid, and the associated changes in electrical admittance spectra in the sensor resulting from changes in fluid acoustic properties. A leaf cell resonator sensor may be capable of retrieving a density and sound speed measurement from fluid independent of the method of deployment, resulting from the principle of the self-formed Helmholtz resonant cavity feature that develops a standing acoustic wave pattern in the fluid without extraneous reflecting structure/hardware.

Abstract: Electromagnetic metamaterial cells are described. An example of an electromagnetic metamaterial cell includes spatially separate absorptive features disposed in a planar rotationally symmetric arrangement. Each of the absorptive features may include a curvilinear segment that is convex relative to a center of symmetry of the arrangement. In some embodiments, each of the absorptive features includes one or more forks extending from the curvilinear segment. Each of the one or more forks may include a stem and at least two tines extending from the stem. The electromagnetic metamaterial cell may be included in a detector, such as a microbolometer, which itself may be included in a Fourier-transform infrared spectroscopy (FTIR) system. In some embodiments, the FTIR system may be used to characterize fluid in a wellbore. The fluid may be a drilling fluid or a downhole fluid, such as crude oil.

Abstract: Systems and methods for vibration attenuation, and for investigating a subsurface volume of interest from a borehole. System embodiments may include a vibration attenuation system, comprising: at least one vibration attenuator configured to dynamically isolate a vibration source, the at least one vibration attenuator comprising metamaterial defining a plurality of cells; wherein at least one cell of the plurality of cells comprises a plurality of sub-cells azimuthally arrayed about an axis of alignment, and at least one sub-cell of the plurality is defined by a solid, the at least one sub-cell including a plurality of cell segments substantially oriented in alignment with a mapping geometry comprising an inversion of a canonical tangent circles mapping. The vibration source may comprise an acoustic source. The system may have an enclosure having the acoustic source and the at least one receiver disposed therein, with the at least one acoustic attenuator is positioned between.

Abstract: Systems and methods for vibration attenuation, and for investigating a subsurface volume of interest from a borehole. System embodiments may include a vibration attenuation system, comprising: at least one vibration attenuator configured to dynamically isolate a vibration source, the at least one vibration attenuator comprising metamaterial defining a plurality of cells; wherein at least one cell of the plurality of cells comprises a plurality of sub-cells azimuthally arrayed about an axis of alignment, and at least one sub-cell of the plurality is defined by a solid, the at least one sub-cell including a plurality of cell segments substantially oriented in alignment with a mapping geometry comprising an inversion of a canonical tangent circles mapping. The vibration source may comprise an acoustic source. The system may have an enclosure having the acoustic source and the at least one receiver disposed therein, with the at least one acoustic attenuator is positioned between.

Abstract: Electromagnetic metamaterial cells are described. An example of an electromagnetic metamaterial cell includes spatially separate absorptive features disposed in a planar rotationally symmetric arrangement. Each of the absorptive features may include a curvilinear segment that is convex relative to a center of symmetry of the arrangement. In some embodiments, each of the absorptive features includes one or more forks extending from the curvilinear segment. Each of the one or more forks may include a stem and at least two tines extending from the stem. The electromagnetic metamaterial cell may be included in a detector, such as a microbolometer, which itself may be included in a Fourier-transform infrared spectroscopy (FTIR) system. In some embodiments, the FTIR system may be used to characterize fluid in a wellbore. The fluid may be a drilling fluid or a downhole fluid, such as crude oil.

Abstract: This specification describes a leaf cell resonator sensor based on a geometry of Rhodonea conformal contours joined circumferentially in an eight-fold symmetry by central spoke electrode members. The resonator sensor may provide simultaneous and congruent measurement of fluid density and sound speed based on interaction of the leaf cell dynamics with self-formed Helmholtz cavity dilatational response of the fluid, and the associated changes in electrical admittance spectra in the sensor resulting from changes in fluid acoustic properties. A leaf cell resonator sensor may be capable of retrieving a density and sound speed measurement from fluid independent of the method of deployment, resulting from the principle of the self-formed Helmholtz resonant cavity feature that develops a standing acoustic wave pattern in the fluid without extraneous reflecting structure/hardware.

Abstract: A system and method of estimating properties of a wellbore fluid that directs the fluid through a cavity, and generates acoustic waves in the fluid while in the cavity. The acoustic waves are generated by oscillating an electroactive material over a range of frequencies. An electrical admittance spectra of the electroactive material is measured over the range of frequencies; where the electrical admittance spectra includes the magnitude, real, and imaginary components. Differences between the maximum values for each component and a vacuum electrical spectra are calculated, the differences are substituted into estimator equations to estimate the fluid properties. Electrical admittance spectra of the electroactive material was simulated for a series of known fluids flowing through the cavity, and a multi-regression statistical analysis was then used to derive the estimator equations.

Abstract: Apparatus, systems, and methods for investigating a subsurface volume of interest from a borehole. Apparatus comprise an enclosure configured for conveyance along the borehole; an acoustic source in the enclosure configured to generate acoustic signals; a lens assembly disposed in the enclosure and next to the acoustic source, the lens assembly being formed of a plurality of lens elements; wherein each lens element comprises a plurality of cells arranged in a curvilinear cell array, each cell formed as a column oriented transverse to a direction of travel of the acoustical signals. The plurality of cells may be arranged according to a conformal mapping geometry, including a canonical Bipolar conformal mapping transformation of constant [u,v] contour lines to [x,y] Cartesian coordinates. A portion of the cells are scaled down in size by a scale factor. The scale factor corresponding to each cell of the portion varies non-monotonically along periodicity lines.

Abstract: Apparatus, systems, and methods for investigating a subsurface volume of interest from a borehole. Apparatus comprise an enclosure configured for conveyance along the borehole; an acoustic source in the enclosure configured to generate acoustic signals; a lens assembly disposed in the enclosure and next to the acoustic source, the lens assembly being formed of a plurality of cells, each cell formed as a column oriented transverse to a direction of travel of the acoustical signals. Each cell comprises a plurality of cell segments with each cell segment of the plurality comprising at least one arcuate wall and at least one radial finger, and wherein the cell segments are oriented in alignment with a rhodonea conformal mapping geometry in a plane transverse to the column to cause acoustic waves to travel at a different speed in each of three orthogonal directions.

Abstract: An acoustic transmitter includes: an acoustic diaphragm configured to transmit acoustic waves into a medium; a piezoelectric actuator assembly configured to deform in an axial direction in response to an applied electrical signal; and a highly incompressible elastic material disposed between the piezoelectric actuator and the acoustic diaphragm and configured to transmit pressure waves to the acoustic diaphragm in response to motion of the piezoelectric actuator.

Abstract: An apparatus for protecting a module used in a borehole may include a plurality of shock protection elements associated with the module. The plurality of shock protection elements cooperatively has a macroscopic non-linear spring response to an applied shock event. The plurality of shock protection elements may include at least an enclosure and a dampener connecting the module with the enclosure. A related method for protecting a module used in a borehole may include enclosing the module within the plurality of shock protection elements; disposing the module in the borehole; and subjecting the module to a shock event. The plurality of shock protection elements cooperatively has a macroscopic non-linear spring response to the shock event.

Abstract: Apparatus, systems, and methods for investigating a subsurface volume of interest from a borehole. Apparatus comprise an enclosure configured for conveyance along the borehole; an acoustic source in the enclosure configured to generate acoustic signals; a lens assembly disposed in the enclosure and next to the acoustic source, the lens assembly being formed of a plurality of cells, each cell formed as a column oriented transverse to a direction of travel of the acoustical signals. Each cell comprises a plurality of cell segments with each cell segment of the plurality comprising at least one arcuate wall and at least one radial finger, and wherein the cell segments are oriented in alignment with a rhodonea conformal mapping geometry in a plane transverse to the column to cause acoustic waves to travel at a different speed in each of three orthogonal directions.

Abstract: Apparatus, systems, and methods for investigating a subsurface volume of interest from a borehole. Apparatus comprise an enclosure configured for conveyance along the borehole; an acoustic source in the enclosure configured to generate acoustic signals; a lens assembly disposed in the enclosure and next to the acoustic source, the lens assembly being formed of a plurality of lens elements; wherein each lens element comprises a plurality of cells arranged in a curvilinear cell array, each cell formed as a column oriented transverse to a direction of travel of the acoustical signals. The plurality of cells may be arranged according to a conformal mapping geometry, including a canonical Bipolar conformal mapping transformation of constant [u,v] contour lines to [x,y] Cartesian coordinates. A portion of the cells are scaled down in size by a scale factor. The scale factor corresponding to each cell of the portion varies non-monotonically along periodicity lines.

Abstract: An apparatus for investigating a subsurface volume may include an acoustic transducer disposed in an enclosure and generating acoustical signals, an electronics assembly disposed in the enclosure and controlling the acoustic transducer, and a lens assembly. The lens assembly may be disposed in the enclosure and next to the acoustic transducer. The lens assembly may be formed of a plurality of cells. Each cell may be formed as a column oriented transverse to a direction of travel of the acoustical signals. Each cell may have a hub, a plurality of spokes radiating from the hub, and a plurality of fingers circumferentially distributed around the hub. The hub, spokes, and fingers may be oriented to cause the acoustic waves to travel at a different speed in each of three orthogonal directions. A related method uses the apparatus in a wellbore.

Abstract: A system and method of estimating properties of a wellbore fluid that directs the fluid through a cavity, and generates acoustic waves in the fluid while in the cavity. The acoustic waves are generated by oscillating an electroactive material over a range of frequencies. An electrical admittance spectra of the electroactive material is measured over the range of frequencies; where the electrical admittance spectra includes the magnitude, real, and imaginary components. Differences between the maximum values for each component and a vacuum electrical spectra are calculated, the differences are substituted into estimator equations to estimate the fluid properties. Electrical admittance spectra of the electroactive material was simulated for a series of known fluids flowing through the cavity, and a multi-regression statistical analysis was then used to derive the estimator equations.