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Patent of the Month - Anisotropic Metamaterials

Patent of the Month – Anisotropic Metamaterials

| On 01, Jul 2018

Darrell Mann

Our patent of the month this month takes us to the University of Texas in one of my favourite cities, Austin. US9,893,432 was granted to a pair of inventors on February 13. I have to admit it nearly slipped through our net. Read the word ‘metamaterial’ in patents these days and it already feels like old news. Additive manufacturing opens up a whole new world of design opportunities. We get it. And so, apparently, does every 3D-printer owning academic and researcher on the planet. What US9,894,432 recognises, however, is that in amongst all of the great opportunities are a series of new problems. Here’s what they have to say on the subject in a mercifully brief and to-the-point background description:

The present disclosure relates generally to methods and systems for improving compatibility of electromagnetic devices and components while reducing coupling and cross-talk by manipulation or sculpting of near field electronic and magnetic fields of electronic and electromagnetic components.

3D printing is poised to revolutionize manufacturing and transform the way electronics and electromagnetic devices are designed and manufactured. It offers the ability to arbitrarily place different materials in three dimensions with high precision. This capability will help to break away from traditional planar designs and to utilize the third dimension like never before. More functions can fit into the same amount of space, products with novel form factors can be more easily manufactured, interconnections can be routed more smoothly, interfaces can be better implemented, electrical and mechanical functions can be comingled, and entirely new device paradigms will be invented.

However, moving away from traditional planar topologies creates many new problems–like signal integrity, crosstalk, noise, and unintentional coupling between devices or components. A number of solutions have been proposed that reduce coupling and cross talk, including hole fences, guarded ground tracks, step shaped transmission lines, and even faraday cages. All of these approaches, however, use metals and can produce new problems in the framework of a 3D system because the isolation structures themselves occupy space, limit how closely components can be placed, and introduce electrical losses.

Or, put in lay-person terms, the ability to manufacture in three-dimensions creates a number of emission and (electromagnetic) compatibility issues. Here’s how we might map that conflict onto the Contradiction Matrix:

Which, all in all looks like it gives pretty good alignment with the strategies found in the inventors’ solution:

An electromagnetic device, comprising: a first layer comprising a first material having a first dielectric constant, the first layer comprising a plurality of channels (Principle 3, Local Quality) or holes (Principle 31, Porous Materials) filled with a second material (Principle 7, Nested Doll) having a second dielectric constant that is different from the first dielectric constant (Principle 3); and a second layer (Principle 1, Segmentation) comprising a plurality of antennas disposed on the first layer; wherein adjacent ones of the plurality of channels of the first layer have an average spacing (Principle 2, Separation) therebetween of less than one quarter of an operating wavelength of at least one of the plurality of antennas….

… In certain aspects a device has one or more electromagnetic components embedded in an AM or SVAM comprising an array of asymmetric (Principle 4, Asymmetry)  unit cells comprising a substrate forming a plurality of channels, spaces, or lattice points for a second material, at least one material having different electromagnetic properties (i.e. dielectric constant, permeability, conductivity, etc.) (Principle 35, Parameter Changes) forming an anisotropic metamaterial or a spatially variant anisotropic metamaterial…

…In a further aspect one or more of the AM or SVAM layers can be a recessed portion (Principle 17, Another Dimension).

…The term antenna refers to a device that can transmit or receive electromagnetic waves (Principle 28, Mechanics Subsitution – i.e. ‘fields’) including radio frequencies, microwave frequencies, THz frequencies, infrared, light, x-ray, etc.

While I’m fairly certain the inventors didn’t use TRIZ, they pretty much came up with a text-book example of how TRIZ could have been used. Pretty much everything they did, the Matrix would have told them to do. Maybe (Principle 14) curvature is the only missing ingredient… unless you know better?