Stage I: printed electrodes in sensors

Citation

(2009), "Stage I: printed electrodes in sensors", Sensor Review, Vol. 29 No. 4. https://doi.org/10.1108/sr.2009.08729dab.004

Stage I: printed electrodes in sensors

Article Type: News From: Sensor Review, Volume 29, Issue 4

Where the sensor makers have seen the value of organic and printable electronics to date is mostly in the area of printed electrodes. The feeling in at least some segments of the sensor industry is that printing can potentially reduce manufacturing costs for sensors of all kinds, and that’s extremely important for smart packaging and point-of-care medical diagnostics, where there is pent-up demand for less expensive devices. The ability to print large sensor arrays on flexible substrates will find particular favor in a number of sensor segments – in architecture and construction, for example, protective clothing and military uniforms, smart labels and packaging, robotics, aerospace, the automotive industry and most certainly homeland security. But what inks does one use?

In the past few years, a slew of new conducting, insulating and semiconducting materials have appeared for use in organic and printable electronics. Silver has historically been the most common electrode material used in thick-film (i.e. screen printed) electronics. Not only is silver the most conductive material known, but when it oxidizes, the oxide is also reasonably conductive. Silver is, of course, relatively expensive, but NanoMarkets believes it will remain the preeminent printed electrode material for some time, especially considering the enhanced performance demonstrated by the latest nanoparticle silver inks.

It’s hard to see silver being pushed out of its prominence, short of an apocalyptic price rise. But should it do so, copper might provide an alternative. But copper oxide is non-conductive and in particulate form, copper is quite dangerous, with a nasty tendency to burst into flames. There are, however, new processes such as special forms of electroplating that favor the use of copper for the electrodes in electronic sensors and other devices. Nickel inks are also a possible silver replacement if push comes to shove and such inks have found use in some thick-film electronics applications.

Then there’s gold ink. For obvious cost reasons, gold is not widely used in printed electronics today, but because it has long been established as safe for medical implants, gold may have a special role to play in medical sensors. When NanoMarkets talked with firms that produced gold inks recently we found that they were doing a brisk – if niche-like – business with their products.