Smart inks and coatings allow the product on which it is printed to communicate with the persons or system that is interacting with it. We see this being used for food packaging – to communicate the freshness of the contents, on RFID labels to transmit authentication information and also in color change pigments on a variety of products.
According to a report from NanoMarkets, the global smart packaging market is already in excess of $14 billion. We suspect that the numbers are significantly higher than that given the ubiquitous nature of smart coatings in both the private and government sectors. At Ink Intelligence we design and formulate smart inks and coatings for packaging, electronics, medical applications and for the Department of Defence. So we see a number of current and future possibilities for smart inks.
Case studies of functional Inks and coatings
Case 1: Stray Light Suppression
In the arena of military hardware, Stray light suppression technology is used to create high heat resistant, radar /thermal imaging “resistant” coatings for military vehicles. These specialized coatings are used to render a surface “nighttime invisible” and invisible to radar and thermal/IR scanners, and although this isn’t new, some of the technology that we’ve developed over the past couple of years enables us to build in even more functionality to what is in essence a camouflage coating.
Radar is a sensitive detection tool, and so what we and others have done is create a coating which impedance matches or acts as a resonant absorber for reducing microwave reflections, and this is done using a variety of materials including metals, carbon in the form of modified carbon nanotubes (CNT) carbonyl iron and hexaferrites used in magnetic RAM, conducting polymers such as polypyrrole and even lattices made from the same. The other aspect of resonant absorbing material (RAM) is that it can be made adaptive by using devices which use a dielectric fluid cell placed behind a resistive sheet. This creates a type of circuit which can then be tuned to different capacitance and resistance.
Of course when it comes to stealth in general, there is a lot that goes into making a vehicle undetectable, including the shape and design of the vehicle, the cleanliness of the vehicle surface and also the external colors.
Case 2: Printed “Skin”
In today’s environment we can take a printer that you might use to print a sales report in your office and use it to print a new layer of skin to medically treat burns or to apply a cosmetic skin layer. Okay, so there are some modifications that need to be made on that printer, but we think that printable skin might be the ultimate smart coating, and while this is not new, the ease by which we can do this has increased tremendously over the past couple of years, and the degree of innovation is growing exponentially.
Diagram 2. Photo: Courtesy of PFSK.
There are a number of different printer configurations that are being used to do this, including thermal print head technology (HP) and 3D bio-printers like the PrintAlive Bioprinter which works by depositing the two types of skin cells – fibroblasts and keratinocytes in a multi-layer gel. The gel, also known as a hydrogel, has a very high biocompatibility which promotes cell growth and vascularization. The use of 3D printers makes this process even more attractive, essentially allowing you to lay down a thicker film of coating than you would be able to with a conventional printer. Viscosity and particle size restricts the type of fluids that can be printed by a typical piezo or thermal print head. This puts obvious limitations on these printers. A 3D printer can be modified to handle a wide range of viscosities and is not limited by the size of particles, so you’ll see a number of 3D printers that use syringe extruders to inject functional materials onto the substrate.
If you’re interested in learning more about 3D bio printers, you can find information here: https://3dprintingindustry.com/news/top-10-bioprinters-55699/
Case 3: Adaptive Color System
When it comes to smart inks, Ink Intelligence is finessing what we consider to be one of the most significant smart inks of our time. We call it the Dynamic Adaptive Color System or DACS.
DACS is a unique bio-based system that has built-in intelligence. How is it intelligent? DACS ink has the ability to mimic the color that surrounds it. In effect it is self-camouflaging, and how it accomplishes that is by using certain types of organic chromophore – combining different layers of proteins within a substrate, and allowing them to operate in unison to achieve a wide spectrum of color possibilities. This is similar to the way a chromatophore works in a cuttlefish; each group of cells contain elastic saccules that contain the pigment (colorant), as well as up to 25 muscles attached to each saccule. When the muscles contract, they stretch the saccule allowing the pigment inside to expand over a larger surface area. When the muscle relaxes, the saccule shrinks and hides the pigment. A layering system gives DACS the ability to produce metallic shades of greens, blues, gold and silver, which act to reflect light to add concealment when required.
Diagram 3: Example of the Octopus vulgaris changing color
An interesting video presentation of the above can be seen here:
Below are examples of the array of colorful and changeable skin of cephalopods:
Obviously this kind of smart technology has a number of possible applications both in the private and government sectors – military uniforms, general apparel, hunting gear, tents, hides and so on.
Creating Smart Inks
A useful methodology for creating smart inks is to think about how you could take an existing product and make it do something else. Today’s printing technologies allow us to print thinner and thinner films, which lends itself well to wearable products like watches and even clothing.
Smart inks and coatings are another layer of sophistication in the evolving field of ink and coatings development. And one of the most exciting aspects of these developments is that we can use it to enhance our daily lives by creating new products that make our lives easier and more productive. In the coming years we’re going to see things that today are only science fiction!