Thursday, May 28, 2015

Setting Up Your Printer

Getting started with printing circuits is a relatively simple and inexpensive process. There are three main things you will need; an inkjet printer, conductive ink, and a substrate.

When selecting a printer, almost any inkjet printer will work. Some researchers claim that it is best to use a piezo-driven printer rather than a thermal-driven one as it is less likely to alter the structure and properties of the conductive ink.[1] It doesn’t need to have fancy touchscreen controls or wireless connectivity. Just look for a cheap printer that you would feel comfortable taking apart and modifying. Studies have shown that Brother Co. printers are the preferred option when it comes to printing circuits due to their nozzles releasing higher volumes of ink. [2] More ink on the page means that there is a better chance of a solid connection or trace being made. The projects on this blog will use a Brother MFC-J450DW. This model was chosen mostly due to the fact that it was the cheapest on Amazon for about $80 at the time of writing. It is also recommended that you purchase empty refillable ink cartridges that are compatible with your model of printer. Trying to reuse the standard ink cartridges may end up contaminating your conductive ink and lead to poor connections. These refillable cartridges can range anywhere from $5-20 depending on the model of printer they are for.

Next you will need the ink. There are many properties such as viscosity, surface tension, volatility, and particle size that need to be taken into consideration for choosing a suitable ink. Luckily, an extensive amount of research has already been done on this and there is a clear winner. Silver nanoparticle ink, part number NBSIJ-MU01, from Mitsubishi Paper Mill works the best for most applications.[3] This ink can be purchased from Diamond-Jet for $340.00 per 100 ml.[4] Admittedly, this does sound like a daunting price at first. However, most conventional ink cartridges only contain between 10 – 15 ml of ink inside of them. So overall the price per ml isn’t that much more expensive. With a 100 ml of silver nanoparticle ink you will be able to print hundreds of circuits.

Another benefit of the NBSIJ-MU01 ink which helps justify the price is that it is chemically sintered. Sintering is the process which take a powdered material or solution and transform it into a solid. With inkjet printing the printer does not print continuous lines. The printer prints many small drops of ink. The sintering process helps combine the silver nanoparticles in these drops together thus creating a complete circuit. Traditionally, the inks would have to be sintered or “baked” in an oven for a few hours so that the solidification process would take place.[5] Chemically sintered silver nanoparticles are dissolved in a special solvent that allows for the reaction to take place just seconds after it is printed.[2] This dramatically reduces the time it takes to prototype a circuit.  

The only thing left is the substrate. Choosing a proper substrate is important because it dictates how well the ink will adhere and last. There can be a lot of experimentation still done with the substrates as some may work better in certain situations than others. Some good baseline substrates are resin coated paper, white and transparent PET film, inkjet paper, and glossy photo paper.[6]

Now hook up your printer, fill and insert your ink cartridges, and start printing!

[1]          M. M. Tentzeris, “Inkjet-Printed Nanotechnology-Enabled Zero-Power Wireless Sensor Nodes for Internet-of-Things (IoT) and M2M Applications,” ATHENA Research Group, School of ECE , Georgia Institute of Technology, Atlanta, GA, 30332-250, USA.
[2]          Y. Kawahara, S. Hodges, B. S. Cook, C. Zhang, and G. D. Abowd, “Instant inkjet circuits: lab-based inkjet printing to support rapid prototyping of UbiComp devices,” 2013, p. 363.
[3]          P. H. King, J. Scanlan, and A. Sobester, “From Radiosonde To Papersonde: The Use of Conductive Inkjet Printing in the Massive Atmospheric Volume Instrumentation System (MAVIS) Project,” 2015.
[4]          “NBSIJ - Silver Nanoparticle Ink - 100ml-1,” Mitsubishi Imaging (MPM), Inc. [Online]. Available: [Accessed: 28-May-2015].
[5]          T. Falat, B. Platek, and J. Felba, “Sintering process of silver nanoparticles in ink-jet printed conductive microstructures - Molecular dynamics approach,” 2012, pp. 1/5–5/5.
[6]          Y. Kawahara, S. Hodges, N.-W. Gong, S. Olberding, and J. Steimle, “Building Functional Prototypes Using Conductive Inkjet Printing,” IEEE Pervasive Comput., vol. 13, no. 3, pp. 30–38, Jul. 2014.

What Are Printed Electronics?

Printed electronics can refer to a wide range of techniques that are used to print electrical devices onto a substrate. A substrate is just the technical term for any substance that the printing process takes place on such as paper, glass, cover slips, etc. The techniques for printing electronics are still largely being developed. Some of the main techniques include screen printing[1], rotogravure[2], and inkjet.

Why use printers at all for electronics? Currently there are two main ways of prototyping a circuit, breadboards and printed circuit boards (PCB). They both have their own pros and cons. A breadboard allows for a cheap way to easily connect wires and different components. However the standard layout of a breadboard means that you must conform your parts to fit what you are given.[3] A PCB can be designed to suit the exact needs of the project you are working on. The manufacturing costs of the PCB are its downfall for hobbyists however. It can take weeks to have your order made and shipped to you or the use of potent chemicals if you wish to etch it yourself.[4] The ability to print electronics on demand combines the best qualities of a breadboard and PCB. They are cheap to print, easy to add parts to, and can be revised very quickly. Printing electronics is becoming to the electronics industry what 3D printing has become to the mechanical industry.

This blog will focus on the inkjet printing method for it is the cheapest and easiest method for hobbyists to get started with. Inkjet printers work mainly by one of two ways. The first being a “Thermal Bubble” where a current is first sent through tiny resistors in the print head. These resistors give off heat and vaporize some of the nearby ink. This vaporization of the ink creates a gas bubble which, as it expands, pushes ink out of the nozzle in the form of tiny droplets. When the bubble eventually pops, a vacuum is created in its absence which refills the nozzle with ink.[5]

The second method is known as a “Piezoelectric” printer. Piezoelectricity is a material property where if a mechanical stress is applied, an electric potential is created. The opposite is also true, if a piezoelectric material is exposed to a change in electric potential energy, then its volume will change.[6] Piezoelectric printers utilize this property by having piezoelectric crystals in the print head’s ink reservoir. When a voltage is applied to these crystals they deform and expel tiny ink droplets out of the nozzle. [5]


[1]          “Screen printing,” Wikipedia, the free encyclopedia. 27-May-2015.
[2]          “Rotogravure,” Wikipedia, the free encyclopedia. 23-May-2015.
[3]          “How to Use a Breadboard -” [Online]. Available: [Accessed: 28-May-2015].
[4]          “How-To: Etch a single sided PCB,” Hackaday. .
[5]          “ - Online.” [Online]. Available: [Accessed: 28-May-2015].
[6]          “The Piezoelectric Effect - Piezoelectric Motors & Motion Systems.” [Online]. Available: [Accessed: 28-May-2015].