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3D Microscale Isotropic and Anisotropic Metamaterials

Technology #20170289

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Researchers
Jeong-Hyun Cho
Assistant Professor, Electrical & Computer Engineering
External Link (ece.umn.edu)
Managed By
Kevin Nickels
Technology Licensing Officer 612-625-7289
Patent Protection

Provisional Patent Application Filed
Publications
Three-Dimensionally Coupled THz Octagrams as Isotropic Metamaterials
ACS Photonics, 2017, 4 (10), pp 2436–2445
Three-Dimensional Anisotropic Metamaterials as Triaxial Optical Inclinometers
Scientific Reports, Vol 7, Article number: 2680(2017)

Microscale Metamaterial for Orientation-Invariant Sensing

A new sensor design features a three-dimensional (3D) metamaterial consisting of microcubes patterned with split-ring resonators (SRR).

  • The first method has patterns of tilted SRRs of different sizes onto the faces of a 3D microscale cube, resulting in anisotropic behavior and achieving unique optical properties. The frequency response is based on the rotation angle of the 3D metamaterial. The 3D anisotropic SRR can be utilized for remotely monitored rotation sensors with low-on chip power that can sense a full 360 degree range.
  • Another SRR sensor consists of a polymer cube, with a gold “X” patterned on each side of the cube, and 3D splits at the corners between the “X” patterns. The 6 faces of the cube together to form an octagram split-ring resonator (OSRR). The sensor exhibits an isotropic response to THz radiation when rotated about its z-axis. Furthermore, simulations confirm an isotropic response for all angles of rotation and predict the ability for ultra-high sensitivity sensing by using changes in the amplitude of the resonant response. The sensor is designed for applications where orientation invariant sensing is required (i.e., in-vivo and in-situ biological or chemical sensing where the relationship between sensor and probe is unknown). The technology, made from biocompatible materials, features a perfectly isotropic transmission response that is invariant under rotation, and can be used for fast, non-contact, label-free chemical or biological sensing.

Anisotropic and Isotropic Metamaterials

Depending upon the pattern used (C-shape with tilt or an octagram shape) the 3D cube can act completely anisotropic or completely isotropic. The polymer-based fabrication of the cube also makes it transparent to light apart from the metal structure, so no disturbance in measurement takes place.

  • Anisotropic metamaterials: The 3D structure is a cube with conventional C-shaped resonators, but each face consists of different-sized resonators, and each resonator is tilted at an angle to create an angular offset. The tilt and resonators of the three varying sizes along each axis overcome the isotropy of the 2D structure, and the measurement response of the cube (three peaks corresponding to the three different-sized resonators) presents a unique combination of the three amplitudes for every possible rotation of the cube along all three axes. This completely anisotropic 3D cube acts as a tri-axis inclinometer (angle sensor) or tri-axis gyroscope (angular motion sensor).
  • Isotropic metamaterials: The 3D cube features X-shaped resonators that create SRRs with splits at the corners. Because the splits are three-dimensional, they are equally affected by all the parameters of light. Therefore, the 3D cube, with its octagram resonators (3D star), acts as an isotropic metamaterial that can be used for highly sensitive detection of foreign particles. The strong 3D coupling of each resonator segment to its neighbor enhances the overall sensitivity of the octagram. The strong coupling and using amplitude as a marker for low concentration foreign materials provide the 3D octagram with a much higher sensitivity compared to 2D sensors.

Superior Performance of 3D Micro Devices Compared to 2D Structures

This technology—a 3D SSR with “X” or tilted patterns on each face—overcomes many of the limitations of both isotropic and anisotropic metamaterials.

  • Anisotropic: While split-ring resonators (SRRs) present an attractive avenue for developing micro/nano scale inclinometers (e.g., for medical microbots, military hardware, nanosatellite systems, etc.), the 180° isotropy of their two-dimensional (2D) structure presents a major hurdle. This new design is a three-dimensional (3D) anisotropic SRR that functions as a microscale inclinometer that can remotely sense rotations from 0° to 360° along all three axes (X, Y, and Z) by employing the geometric property of a 3D structure. The THz operating frequency can realize rotation changes down to 1°/ns.
  • Isotropic: SRRs have been studied for developing high sensitivity, small sized, low power sensors for fast and label-free detection of chemical and biological substances, but the anisotropy of their 2D structure presents a major disadvantage when the orientation of the structure cannot be controlled. This 3D isotropic octagram split-ring resonator (OSRR) overcomes the anisotropic response of the 2D structure, leading to a single, polarization invariant transmission response.

The new design generates isotropic transmission response independent of temperature and pressure, allowing for orientation invariant sensing. Its sensitivity is 16 times higher than 2D SRR and is fabrication, from biocompatible materials, is simple and cost-effective.

BENEFITS AND FEATURES:

  • 3D metamaterials
  • Superior performance of 3D micro devices compared to traditional 2D structures
  • Microcubes patterned with split-ring resonators (SRR)
  • Gold “X” patterned on each side of the cube
  • 3D splits at the corners between the “X” patterns
  • Isotropic response for all angles of rotation
  • Anisotropic response for measurement of angle of rotation
  • Anisotropic behavior and unique optical properties
  • Isotropic response to THz radiation when rotated about z-axis
  • Isotropic transmission response invariant under rotation
  • Ultra-high sensitivity sensing ability using changes in the amplitude of the resonant response
  • In-vivo and in-situ biological or chemical sensing
  • Fast, non-contact, label-free chemical or biological sensing
  • Sensitivity is 16 times higher than 2D SRR
  • Made from biocompatible materials
  • Simple and inexpensive fabrication
  • Small size (e.g., antenna)
  • Biocompatible with minimal modifications

APPLICATIONS:

  • Sensors and optical devices
  • Biosensor or sensor in telecommunication (antenna)
  • In-vivo sensing where sensor orientation is uncontrolled
  • In-vivo biological or chemical sensors
  • Small scale biocompatible sensors implanted subcutaneously for in-vivo measurement of biological species
  • In-situ measurement of chemicals present in any liquid
  • Continuous glucose monitor (CGM)
  • Potential for assessing aging of meat products (based on moisture loss)
  • Anisotropic metamaterials:
    • inclinometer, rotation sensor or gyroscope
    • navigation systems or small scale devices
    • saving on-chip power to allow for remote detection
    • medical microbot guidance systems
    • measuring extremely high and low angular velocity (due to its THz operating frequency range)
  • Isotropic metamaterials:
    • biological or chemical sensors
    • subcutaneous implant for in-vivo measurement of biological species while they flow in the blood
    • in-situ measurement of chemicals present in any liquid

Phase of Development - Prototype development

Device fabricated, isotropic/anisotropic resonant response characterized, sensitivity demonstrated experimentally.

Interested in Licensing?
The University relies on industry partners to scale up technologies to large enough production capacity for commercial purposes. The license is available for this technology and would be for the sale, manufacture or use of products claimed by the issued patents. Please contact Kevin Nickels to share your business needs and technical interest in this technology and if you are interested in licensing the technology for further research and development.