One-Step Process Could Lead to Roll-to-Roll Production of Touchscreen Displays

A process known as photochemical metallization could offer cheaper display manufacturing

2 min read
One-Step Process Could Lead to Roll-to-Roll Production of Touchscreen Displays
Photo: INM

Touchscreen displays have two types of conductor paths that enable a finger tap or swipe to trigger some response. There are those that cover the display so that when a finger passes over them, they open and close circuits. Then there are the larger conductor paths that are on the edges of the display, where all the smaller ones converge.

This design has always required a multiple-step manufacturing process that has made production costs high. Now researchers at the Leibniz Institute for New Materials (INM) in Germany have developed a one-step process for producing both of these conductor paths that should dramatically reduce manufacturing costs for touchscreen displays.

While the IMN researchers have not yet published a paper on their research, they will be presenting the results of their work at the Hannover Messe exhibition in Germany later this month.

The key to this one-step process is a technique known as photochemical metallization. In this method, a photoactive layer that undergoes a chemical reaction when in the presence of sunlight or UV light is used. This photoactive layer, which is made up of metal oxide nanoparticles, is overlaid with a silver compound layer that remains stable in UV light. 

When irradiated with UV light, the silver layer disintegrates into the photoactive layer so that the silver ions are reduced to form metallic, electrically conductive silver.

Once the electrically conductive silver is produced it can be deposited onto either glass or plastic to form conductive paths or other structures. These paths, which can be as small as a thousandth of a millimeter, are irradiated again with UV light to create corresponding conductive paths.

There are three of different ways that the conductive paths can be produced, according to Peter William de Oliveira, Head of Optical Materials at IMN. However, thus far the researchers have only used one method: UV lasers, which is fine for prototype manufacturing and testing. However, de Oliveira concedes that this approach is too time consuming for mass production.

Another approach the researchers are considering calls for placing photomasks over the silver-photoactive layers so that the UV light can pass only at the desired positions.

The third method, say the researchers, involves something called “transparent stamps”

“These stamps push out the silver compound mechanically; conductive paths then only occur where there is still silver compound,” de Oliveira said in a press release.

The advantage of this approach is that the stamps are made of a soft plastic that can be arranged into a roll, enabling roll-to-roll manufacturing. The IMN team is now pursuing this avenue by developing a way to embed the UV source directly into the roll.

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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.


If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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