Circuit Scribe is a ball-point pen containing silver conductive ink one can use to draw circuits instantly on flexible substrates like paper. Circuit Scribe made its way onto Kickstarter (an online site where people can fund projects) on November 19, 2013 with its goal of raising $85,000 for the manufacturing of the first batch of pens. By December 31, 2013, Circuit Scribe was able to raise a total of $674,425 with 12,277 ‘backers’ or donors. Similar to drawing a picture, users can use a Circuit Scribe pen to draw lines on a simple piece of paper. They can then attach special electrical components on the drawn lines which allows the electrical currents to run through the components. This replaces the use of breadboards and wires.
A team of researchers in Electroninks Incorporated, a startup company located at Research Park of the University of Illinois at Urbana-Champaign, created a water-based, non-toxic conductive ink that was noted as the Invention of the Month by Popular Science. The team began by developing a prototype using pens from a different company and replacing the ink with their special silver ink. Once completed, they started a Kickstarter campaign to earn funding for a mass production of the final form of the pens.
The researching team consists of S. Brett Walker, Jennifer A. Lewis, Michael Bell, Analisa Russo, and Nancy Beardsly. Walker is the CEO of Electroninks and the co-founder along with Lewis, Bell, and the director of product development, Russo. Bell is also the chief operating officer while Beardsley is the technical support and user experience.
The prototype pens are hand-cleaned Sakura Gelly Roll Metallic pens. The ink is replaced with the researchers’ silver conductive ink. In order to have the right amount of ink flow to make smooth lines, the ink is precisely tuned.
The ink is created by placing an aqueous solution of silver nitrate into a flask of water combined with polyacrylic acid (PAA) and diethanolamine (DEA), the capping agent and reducing agent, respectively. After about twenty hours, the silver nitrate is dissolved, forming particles with a diameter of about 5 nanometers. In order to enlarge the size of the particle to an average diameter of about 400 nanometers, the flask is placed on a heated sonicator, a device that produces high-intensity ultrasound. Once cooled, the solution is poured into a larger flask and the thick precipitate, an insoluble solid which is formed is scraped out. From there, ethanol is added to coagulate the particles, or change the particles to a solid state. Most of the supernatant, the liquid lying above a layer of the precipitate, is then poured out so the remaining liquid can be centrifuged, or separated. After the process of centrifugation, the particles are placed back in water and forced through a syringe filter to remove unnecessary particles in the solution. Next, hydroxyethyl cellulose (HEC) is added as a binder and the entire mixture is homogenized. The solvents are allowed to evaporate until the ink has a desired viscosity or thickness. Once the ink is created, a roller ball pen is dismantled and cleaned so the ink can be placed inside using a flat tip spatula. After replacing the roller ball tip, a couple blasts of compressed air is shot from the back end to force the ink into the tip. The outer cover of the pen is replaced and the prototype of the Circuit Scribe is created. From there, the team launched its Kickstarter campaign.