Technology

Innova Dynamics has invented and developed an entirely new way to impart new functionalities to surfaces and devices.  Innova Dynamic’s core Innlay™ technology platform enables the embedding of nearly any type of functional additive into the surface of polymers to produce Innlay™ surface-embedded structures. These proprietary structures can add powerful new properties to a surface or device, while retaining the properties of the underlying substrate.  

The Innlay™ embedding technology platform is versatile.

Functional additives can be anything ranging from inorganics or organics, particles that are micron-sized to nano-sized in scale, and even molecules. For transparent conductive electrode (TCE) applications, Innova currently uses the Innlay™ embedding technology to embed highly conductive silver nanowires (AgNWs) directly into the surfaces of transparent conductive films. For IonArmour® antimicrobial applications, Innova employs Innlay™ technology to embed  silver-glass particles, or quaternary ammonium compounds.

Virtually any material that can be swellable can serve as an embedding material, or ‘host-material.’ Common host-materials include most polymers and sol gels, including plastic films­­. Even substrates that are not swellable – like metals, ceramics, semiconductors, certain fabrics, etc. – can be functionalized using the Innlay™ surface-embedding technology by first applying a host material to the surface -- like acrylate, epoxy or urethane polymers – and then Innlay™ embedding particles. 
How Innlay™ technology works 

The Innlay™ embedding technology platform is simple.

Innlay™ AgNW inks are formulations of conductive nanoparticles, a special blend of solvents and stabilizing additives. Unlike traditional coatings, these inks contain no binders, because AgNWs are Innlay™ surface-embedded directly into the substrate, which serves as the host polymer.  This represents a major distinction from conventional AgNW  technologies where binders serve as the matrix for discrete coating layers on top of a base film or substrate.

The Innlay™ embedding process is performed with standard wet deposition equipment (e.g. slot die coating) and occurs within seconds. The solvent blend is designed to perform 3 steps in the Innlay™ embedding process.
1. Deposition & dispersion

The solvent blend provides a low-viscosity vehicle or carrier for the deposition and dispersion of the particles across a surface. In the case of Innlay™ AgNW inks, a conventional coating method like slot die coating is performed with standard roll-to-roll equipment. For anti-microbial applications, spray- or dip-coating are common deposition methods.

Once the AgNW inks are applied to the surface to form a wet film, the AgNWs rapidly settle to form a two-dimensional network. Given the absence of binders, no foreign materials get between the wires to impede junction connectivity and increase junction resistance between the wires.

2. Swelling & Dissolution

The solvents blends are also designed to swell, if not partially dissolve, the host substrate.  As this occurs, polymer chains reach above the original substrate surface while capillary forces draw the particles into this now softened surface. In the case of Ag nanowires, the mesh structure is retained as the nanoparticles are embedded into the solvated polymer surface.

3. Drying & Physical Embedding

Lastly, the solvents are designed to dry in a controlled fashion. As they dry, the solvated or dissolved polymer chains re-entangle around the particles, thereby physically embedding the particles. The solvent blend is designed to allow the host polymer to retain its original properties. But now, the surface has the added functionality from the physically embedded particles.
Please see the following animation of the process, Figure 1.

Figure 1
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The properties of this Innlay™ surface can be further tailored by controlling the depth of embedding. This can be done by selectively varying the ink formulation and deposition and drying conditions.

The upper photo and schematic in Figure 2 show a partially-embedded Ag Nano Wire Network. The lower photo and schematic in Figure 2 show a near-fully-embedded Ag Nano Wire Network.

For TCE applications, the near-fully embedded structure is preferred to obtain protection of the Ag nanowires from environmental degradation while still providing some exposure of the Ag nanowires at the surface for ohmic-contact ease.

For IonArmour® applications, a partially-embedded structure is preferred to enhance the exposure of the antimicrobial particles at the surface to bacteria.
Figure 2
Superior Performance for a Given Particle

The quality of particles plays an important role in any composite. However, the Innlay™ embedding process and resulting structures provide a powerful means of maximizing the efficacy of a given particle in a composite structure.

In the case of TCE films, Innlay™ embedding enables the use of lower AgNW loadings to achieve the same conductivity as conventional, discrete layer structures, which inherently have binder between Ag nanowires, and thereby impede conductivity. This translates to Innlay™ TCE film structures with fewer Ag nanowires that impede and scatter light, and in turn, higher transparencies and lower haze levels for a given sheet resistance.

Moreover, the host polymer of an Innlay™ TCE film provides a dense matrix that encases and protects Ag nanowires from the environment. 

Conventional, discrete-layer silver nanowire composites are fundamentally different. Binder levels in their inks are kept low to minimize the disruption of Ag nanowire junctions and to maintain coatable viscosity levels.  Binder loading is insufficient to produce dense, hermetic matrices for the Ag nanowire composite. Consequently, several additional process steps are required to ensure adequate environmental protection, and in turn, ohmic contact. A polymer over coat is applied and cured to provide environmental protection to the underlying porous, discrete-layer composite of binder and Ag nanowires. The Ag nanowires are now buried under this polymer overcoat. To achieve ohmic contact, an additional etching step is now required to re-expose the Ag nanowires.

Compared to the conventional discrete-layer Ag nanowire coatings, the Innlay™ embedding process and resulting surface structure are inherently simpler, more robust, and lower in cost, while delivering superior optical properties.

For a given antimicrobial particle, the Innlay™ platform delivers superior cost-performance for antimicrobial applications as well.

Figure 3 below illustrates how the IonArmour® platform unrivaled performance than other processes and structures.  Even though the same antimicrobial particles or ingredients are used, IonArmour® surfaces deliver an order-of-magnitude or higher efficacy at killing bacteria.  In case of conventional processes and structures, such as bulk mixtures or discrete-layer coatings (like paint), most of the antimicrobial ingredients s are buried in a matrix and therefore are not available to kill bacteria. In contrast, in a partially-embedded surface structure made by the Innlay™ process, all the antimicrobial particles are exposed on the surface and are active. When compared to any conventional processes and resulting structures, this translates to a dramatic increase in the antimicrobial efficacy and lifetime of IonArmour® surfaces.

Figure 3
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