The Future of Inkjet-Printed Electronics

Silver nanoparticle ink is injected into an empty cartridge and used in conjunction with an off-the-shelf inkjet printer to enable ‘instant inkjet circuit’ prototyping. (Photo courtesy of Georgia Institute of Technology)

Silver nanoparticle ink is injected into an empty cartridge and used in conjunction with an off-the-shelf inkjet printer to enable ‘instant inkjet circuit’ prototyping. (Photo courtesy of Georgia Institute of Technology)

Over the past decade, major advances in additive printing technologies in the 2-D and 3-D electronics fabrication space have accelerated additive processing—printing in particular—into the mainstream for the fabrication of low-cost, conformal, and environmentally friendly electronic components and systems. Printed electronics technology is opening an entirely new world of simple and rapid fabrication to hobbyists, research labs, and even commercial electronics manufacturers.

Historically, PCBs and ICs have been fabricated using subtractive processing techniques such as photolithography and mechanical milling. These traditional techniques are costly and time-consuming. They produce large amounts of material and chemical waste and they are also difficult to perform on a small scale for rapid prototyping and experimentation.

This single-sided wiring pattern for an Arduino microcontroller was printed on a transparent sheet of coated PET film, (Photo courtesy of Georgia Technical Institute)

This single-sided wiring pattern for an Arduino microcontroller was printed on a transparent sheet of coated PET film, (Photo courtesy of Georgia Technical Institute)

To overcome the limitations of subtractive fabrication, over the past decade the ATHENA group at the Georgia Institute of Technology (Georgia Tech) has been developing an innovative inkjet-printing platform that can print complex, vertical ICs directly from a desktop inkjet printer.

To convert a standard desktop inkjet printer into an electronics fabrication platform, custom electronic inks developed by Georgia Tech replace the standard photo inks that are ejected out of the printer’s piezoelectric nozzles. Inks for depositing conductors, insulators/dielectrics, and sensors have all been developed. These inks can print not only single-layer flexible PCBs, but they can also print complex, vertically integrated electronic structures (e.g., multilayer wiring with interlayer vias, parallel-plate capacitors, batteries, and sensing topologies to sense gas, temperature, humidity, and touch).

To create highly efficient electronic inks, which are the key to the printing platform, Georgia Tech researchers exploit the nanoscale properties of electronic materials. Highly conductive metals (e.g., gold, silver, and copper) have very high melting temperatures of approximately 1,000°C when the materials are in their bulk or large-scale form. However, when these metals are decreased to nanometer-sized particles, their melting temperature dramatically decreases to below 100°C. These nanoscale particles can then be dispersed within a solvent (e.g., water or alcohol) and printed through an inkjet nozzle, which is large enough to pass the nanoparticles. After printing, the metal layer printed with nanoparticles is heated at a low temperature, which melts the particles back into a highly conductive metal to produce very low-resistance electrical structures.

Utilizing nanomaterials has enabled the creation of plastic, ceramic, piezoelectric, and carbon nanotube and graphene inks, which are the fundamental building blocks of a fully printed electronics platform. The inks are then tuned to have the correct viscosity and surface tension for a typical desktop inkjet printer.

By loading these nanomaterial-based conductive, dielectric, and sensing inks into the different-colored cartridges of a desktop inkjet printer, 3-D electronics topologies such as metal-insulator-metal (MIM) capacitors can then be created by printing the different inks on top of each other in a layer-by-layer deposition. Since printing is a non-contact additive deposition method, and the processing temperatures are below 100⁰C, these inks can be printed onto virtually any substrate, including standard photo paper, plastic, fabrics, and even silicon wafers to interface with standard ICs with printed feature sizes below 20 µm.

The Georgia Tech-developed printing platform is a major breakthrough. It makes the cost of additively fabricating circuits nearly the same as printing a photo on a home desktop inkjet printer—and with the same level of simplicity and accessibility.

These advancements in 2-D electronics printing combined with current research in low-cost 3-D printing are enabling commercial-grade fabrication of devices that typically required clean room environments and expensive manufacturing equipment. Such technology, when made accessible to the masses, has the potential to completely change the way we think about building, interacting with, and even purchasing electronics that can be digitally transmitted and printed.  While the printing technology is currently at a mature stage, we have only scratched the surface of potential applications that can benefit from printing low-cost, flexible electronic devices.

24 thoughts on “The Future of Inkjet-Printed Electronics

  1. Benjamin,

    I have several projects that I would like to develop for kids (esp. disadvantaged ) to explore Amateur Radio and Basic Electronics. This technology would allow us to move light years ahead. Printable robots? Wearable computing? Wow! Any chances of partnering up some of your technology for some community-oriented DIY/FAB projects?

    Rob Thomas, B.I.D.
    Industrial Designer,
    Amateur Radio Extra License, KC4NYK
    Technology Educator

    • Rob,

      While this is a really powerful technology, it is also great for prototyping simple electronics. My father is actually a high school teacher and has been able to use this technology for teaching his students. If you read the fully published paper ( http://dl.acm.org/citation.cfm?id=2493486 ), we give all of the details on where to get the materials, and how to set up the printer to do this yourself, it is really simple!

      Best,

      Ben

    • Magic,

      We can print metals and dielectrics, therefore, if you pattern the dielectric layers with holes, you can print metal layers on top that will form vias through the holes.

      Best,

      Ben

    • Hello there,
      This type of printers only print on 2D surfaces. You could achive the contact between faces with a small pin.
      I wonder if we could convert a conventional printer into a circuit printer….

      • This is using a conventional $75 Brother printer with no physical modifications – the only modifications have been performed to the ink.

        Best,

        Benjamin Cook

  2. @Joakim Soya: given the high price of “normal” inkjet inks, my guess would be that these special inks will cost a small fortune. But hey, this new technique should save us a lot of hassle! I’m just wondering how solderable these printed contact pads are…

    • Nils,

      You can fill a printer cartridge for about $50 which will last you quite a long time with these inks. They are on par with the price of standard printer inks.

      To solder, we use solders which can adhere to silver, and it does work quite well. We also use conductive epoxies.

      Best,

      Ben

  3. Printing electronic circuits on any substrate may sound fantastic, but how to solder components to this circuits ? Is there also a solder paste type ink that can be printed with an inkjet printer and be cured at the same temperatures that are used to cure the conductor ink ?

  4. One word “fabulous”. I look for further innovations.
    I designed a lot of PCB from drawing table …design programs
    on PC and printing on transparent film and photo sensitive plates.
    It is a pity that i am too old (88) to start in this new area of PCB making
    Wish you a lot of succes.
    A.HELLEBAUT/ BELGIUM

  5. I do like a way to make very black film for photographic make pcb,s I do with laser printer but it is nog dark enough, a special ink in a inkjet is maybe a very good solution.

    regards.

    kees

  6. Conductors that melt together at 100 degrees, well great. Solder that melts at 240 degrees hmmm. Houston I think we have a problem !!!

    • That is why low-temp melt solder, or conductive epoxy is utilized for mounting components.

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  8. Ben-

    Serious prototyping will need at least 2 circuit layers. You allude to 3D capabilities in your comment above, but I don’t see much about this in your published paper. Have you done it successfully? Do you have specific recommendations for dielectric inks? A reliable way to create vias?

    • Jeff,

      Yes, this has been done quite successfully! If you go to my google scholar page you will find many articles on multi layer or “vertically integrated” implementations. Vias are quite easy with this technique. You can also find the ink recipes in these articles.

      Ben

  9. Hello, I use to work at Padtech Industries in mid to late 1990s; we would silk screen print silver conductive inks (used DuPont); very expensive ink, I think around $300 for 200g at that time. We also printed UV curable dielectric inks….this is all thin film tech I guess 3M and DuPont did a lot of the pioneer work back in 1950s or so for the aerospace industry.

    I would like to test this out with an inkjet printer; please give us some links and then some of us could experiment.

    I live near Vancouver, BC (In The North West); and starting to get back into hobbyist electronics.

    TTYL

    -Alex T.