‘Spray-On’ Memory for Paper, Fabric, Plastic

USB flash drives are already common accessories in offices and college campuses. But thanks to the rise in printable electronics, digital storage devices like these may soon be everywhere – including on our groceries, pill bottles and even clothingDuke University researchers have brought us closer to a future of low-cost, flexible electronics by creating a new “spray-on digital memory device using only an aerosol jet printer and nanoparticle inks. The device, which is analogous to a 4-bit flash drive, is the first fully-printed digital memory that would be suitable for practical use in simple electronics such as environmental sensors or RFID tags. And because it is jet-printed at relatively low temperatures, it could be used to build programmable electronic devices on bendable materials like paper, plastic or fabric.

PrintingMemory

Duke University researchers have developed a new “spray-on” digital memory (upper left) that could be used to build programmable electronics on flexible materials like paper, plastic or fabric. They used LEDS to demonstrate a simple application.

We have all of the parameters that would allow this to be used for a practical application, and we’ve even done our own little demonstration using LEDs,” said Duke graduate student Matthew Catenacci, who describes the device in a paper published online in the Journal of Electronic Materials. At the core of the new device, which is about the size of a postage stamp, is a new copper-nanowire-based printable material that is capable of storing digital information.

Memory is kind of an abstract thing, but essentially it is a series of ones and zeros which you can use to encode information,” said Benjamin Wiley, an associate professor of chemistry at Duke and an author on the paper.

Source: https://today.duke.edu/

Scalable Production of Conductive Graphene Inks

Conductive inks based on graphene and layered materials are key for low-cost manufacturing of flexible electronics, novel energy solutions, composites and coatings. A new method for liquid-phase exfoliation of graphite paves the way for scalable production.

Conductive inks are useful for a range of applications, including printed and flexible electronics such as radio frequency identification (RFID) antennas, transistors or photovoltaic cells. The advent of the internet of things is predicted to lead to new connectivity within everyday objects, including in food packaging. Thus, there is a clear need for cheap and efficient production of electronic devices, using stable, conductive and non-toxic components. These inks can also be used to create novel composites, coatings and energy storage devices.

A new method for producing high quality conductive graphene inks with high concentrations has been developed by researchers working at the Cambridge Graphene Centre at the University of Cambridge, UK. The novel method uses ultrahigh shear forces in a microfluidisation process to exfoliate graphene flakes from graphite. The process converts 100% of the starting graphite material into usable flakes for conductive inks, avoiding the need for centrifugation and reducing the time taken to produce a usable ink. The research, published in ACS Nano, also describes optimisation of the inks for different printing applications, as well as giving detailed insights into the fluid dynamics of graphite exfoliation.

graphene scalable production

“This important conceptual advance will significantly help innovation and industrialization. The fact that the process is already licensed and commercialized indicates how it is feasible to cut the time from lab to market” , said Prof. Andrea Ferrari, Director of the Cambridge Graphene Centre.

Source: http://www.graphene.cam.ac.uk/

Nanowire Inks For Printable Electronics

By suspending tiny metal nanoparticles in liquids, Duke University scientists are brewing up conductive ink-jet printer “inks” to print inexpensive, customizable circuit patterns on just about any surfacePrinted electronics, which are already being used on a wide scale in devices such as the anti-theft radio frequency identification (RFID) tags you might find on the back of new DVDs, currently have one major drawback: for the circuits to work, they first have to be heated to melt all the nanoparticles together into a single conductive wire, making it impossible to print circuits on inexpensive plastics or paper. A new study by Duke researchers shows that tweaking the shape of the nanoparticles in the ink might just eliminate the need for heat.

By comparing the conductivity of films made from different shapes of silver nanostructures, the researchers found that electrons zip through films made of silver nanowires much easier than films made from other shapes, like nanospheres or microflakes. In fact, electrons flowed so easily through the nanowire films that they could function in printed circuits without the need to melt them all together.

silvernanostructures

The nanowires had a 4,000 times higher conductivity than the more commonly used silver nanoparticles that you would find in printed antennas for RFID tags,” said Benjamin Wiley, assistant professor of chemistry at Duke. “So if you use nanowires, then you don’t have to heat the printed circuits up to such high temperature and you can use cheaper plastics or paper.”

There is really nothing else I can think of besides these silver nanowires that you can just print and it’s simply conductive, without any post-processing,” Wiley added.

These types of printed electronics could have applications far beyond solar cells; researchers envision using the technology to make solar cells, printed displays, LEDS, touchscreens, amplifiers, batteries and even some implantable bio-electronic devices. The results appeared online Dec. 16 in ACS Applied Materials and Interfaces.

Source: https://today.duke.edu/