Conductive Ink (silver based)
by adedoyin
By: Shan Gao, Jeremy Roc Jih, and Adedoyin Ogunniyi
Conductive ink is a rising technology that is making circuitry available to a larger audience than the traditional method. The ink can be inserted into a standard roller-ball pen which is highly available, cheap, and precise. This pen can then be used to write on paper. Paper is perfect for circuits because it is available, inexpensive, lightweight and biodegradable. Also because paper can be manipulated into 3D configurations, it increases the possibilities for using conductive ink.
Silver based conductive ink is the most effective conductive ink available to us. Unfortunately, silver is very expensive and its price fluctuates too much to be stable (Developments in Conductive Inks). It is made of mostly silver (about 45-55% of the total solution). This percentage insures the right viscousity so that the ink flows without leaking or clogging. Also, it can be wriiten on soft and hard surfaces. The other 45-55% is the fluid solution composed of Diethanolamine and Hydroxyethyl cellulose.
hlt.media.mit.edu/cmi_readings/conductorsPapers/conductivePen.pdf
Silver based conductive ink is highly conductive (it’s mostly made of silver flakes and particles). It’d resistivity decreases after drying. After 30 minutes at room temperature, the resistivity is 1.99×10^(-4)ohm-cm. Impressively, the paper on which a silver based conductive ink circuit has been printed on can be folded and bent many times without affecting the conductivity.
Due to the expensive price of silver, silver based conductive ink is not very popular with the general public. It’s most common use currently, is to make the RFID tags (like the one pictured below).
However, based on the rising popularity of printed circuits over the traditional methods, this technology can be applied to anything. There are already prototypes of interactive wallpapers, books, paintings, and clothing. Also, because these circuits can be printed on almost literally anything, the cost and time for manufacturing circuit boards and prototyping projects can be reduced.
As useful as this ink is, it has some health risks. The main component is, of course, silver. Silver is actually antibacterial and is often used in the medical field (tooth fillings, topical gels and bandages). However, if large quantities are inhaled or ingestid, it can cause argyria (blue skin). One example is paul karason – Google Search. Silver also has less dramatic side effects such as seizures, fatigue and stomach distress.
Other components in silver ink are also only dangerous if ingested in large quantities, and are commonly used ingredients in cosmetics. One of these is called Diethanolamine, a common ingredient that is responsible for the creamy texture and foaming action in shampoo and cosmetics. Another ingredient is Hydoxyethyl Cellulose, also used in cosmetics and household cleaning products. It is frequently used with hydrophobic drugs to assist dissolution in the digestive juices.
Silver based ink can be acquired from these retailers:
M.E. Taylor Engineering, INC.
Silver Paint, 18% Silver, 15 gram brush-cap bottle
SRA Soldering Products and more
CAIG Laboratories, INC.
And of course, Amazon, INC.
Amazon.com: conductive ink: Electronics
If you are interested in a safer conductive ink, check out the Bare Conductive Ink group at: Welcome – Bare Conductive
Bare Conductive Ink is nontoxic and can be applied to the skin for incredible projects like The Humanthesizer.
Presentation: Silver Ink Presentation