The resistance of the ink is 0.5 to 10 ohms for a 1 cm line. However, it depends on the paper that you are writing on. We see about 3 ohms/cm on standard copy paper and 0.5 ohms/cm on photopaper. Our favorite materials are Recollections colored cardstock (available at Michael’s) for craft projects and Epson Ultra Premium Luster Photo paper for PCB applications.
Circuit Scribe is MUCH more conductive! You could not get enough power through graphite traces to power an LED or motor. We measured the resistance of pencil traces to be 5-8 megaohms/cm with a single pass, and 30-60 kilohoms/cm with a lot of scribbling!
Our conductive ink pen is unique because it contains about 20% pure silver by volume, so it acts a little differently from a normal pen. The dense silver particles tend to settle to the bottom of the pen after sitting for more than 24 hours, but they will re-disperse if you shake lightly, draw for a few minutes, or simply carry the pen around in your pocket like we do!
If the ink settles, it is common for the pen to look half-full. However, the pens ship with 1 ml of ink, and if you lightly shake them that entire volume will look full. There is also a white ball at the top of the ink column that indicates the ink level.
An unopened pen has a shelf life of about a year, and we’re optimizing the ink to try to make it last longer. Once it’s open, the pen will write smoothly for at least 6 months. After that time, the tip might dry out, but you can scribble on a damp paper towel to get it working again.
Nope! Not right now, at least. The cost of pen manufacturing is taken up mostly by the silver ink, so the plastic bodies are essentially disposable. We are considering selling ink in other types of containers…in the far future.
Circuit Scribe will write on anything that your everyday rollerball pen will. Regular printer paper, construction paper, cardstock and photo paper all work. The pen is not recommended for woven fabrics but we’ve started trying it on neoprene, leather/vinyl, and Tyvek. Have fun, and experiment on different mediums!
The ink can support a maximum current of ~175 mA on standard copy paper. Higher currents cause joule heating, which creates a drop in resistance due to sintering the particles. Current exceeding 400 mA might break the trace in a thin spot
The maximum voltage depends on the distance of your ground and high voltage (HV) trace. You should also consider the distance the magnetic backing is to the paper (i.e. keep it well-insulated with multiple sheets of paper). We do not recommend using high voltages (above 36V) due to safety.
If any of the modules in your kit do not work upon opening, we will gladly send a new component free of charge. If for any reason you are dissatisfied with your kit, we will accept your kit for a full refund within 90 days of purchase.