A Key to Flexible Electronics: Samsung and Stanford Ease Manufacturing
This month alone has seen plenty of developments in the field of flexible electronics. What are they accomplishing and could this technology be taking steps towards easier manufacturing?
Flexible electronics have been a hot field of research for some time now, and the more time that passes, the more momentum it seems to develop.
Proponents of flexible electronics often envision future technologies used in devices like foldable smartphones, smart textiles, wearable electronics, and implantable sensors; all are heavily invested in academia and industry.
An example of a hybrid system with printed and flexible ICs. Image from American Semiconductor
Still, like any technology in its infancy, there are many obstacles to overcome, especially in that foggy area between university research and getting to market. Fortunately, with the momentum in the field of flexible electronics, developments appear to be happening at blazing fast speeds. This month alone has seen numerous advancements in the field across academia and industry.
This article will discuss two academic developments to see where this industry could be headed and what challenges lie ahead. The first academic venture with flexible electronics comes from Stanford.
Stanford’s Flexible Manufacturing Technique
Recently, Stanford has been attempting to innovate the process of creating flexible electronics.
Most of the effort towards flexible electronics has often involved employing atomically thin 2D electronics, materials with a single atom thickness, making them flexible and bendable while maintaining excellent mechanical and electrical properties. However, the formation of these ultra-thin devices typically requires an extremely hot manufacturing process, so hot that the flexible plastic substrates of the electronics would melt and decompose in the production process.
The transfer process (steps a-f) of the new flexible manufacturing technique. Image from Daus et al
In a new paper from Stanford University, researchers propose a new method of manufacturing these flexible 2D electronics.
The technique consists of taking a non-flexible, solid block of silicon coated with glass and using chemical vapor deposition to grow MoS2 one layer of atoms at a time until it reaches a three atom thickness.
This layering technique forms and cools the critical parts on rigid silicon, allowing the Stanford researchers to apply the flexible material at temperatures up to 850°C without damaging the substrate. A follow-up bath in deionized water causes the device to peel off the substrate and form an entirely flexible polyimide. The end structure, including the polyimide, is just 5 microns thick, about 10x thinner than a human hair.
Through this new process could be interesting to those working in the field of flexible electronics, a question of how feasible it is to bring flexible electronics more into real-world applications and devices?
Samsung’s Opening the Door to Mass Production?
As stated previously, one of the largest challenges for flexible electronics is the manufacturing process. This process can make it challenging to mass produce or implement the process into existing systems.
However, this month, Samsung published a new paper in which they detail how they were able to create a new flexible wearable device, which states that it can be integrated into preexisting semiconductor processes. This innovation might help push the concept of flexible electronics closer towards mass production.
The new device integrates a stretchable OLED display and a photoplethysmography (PPG) sensor into a single flexible unit capable of measuring and displaying the user’s heart rate in real-time, creating, what the researchers are calling, a “stretchable electronic skin.” Capable of undergoing up to 30% deformation without any decrease in performance, this device claims to be able to stretch over 1000 times without issue.
The (A) schematics and (B) photograph of the stretchable "skin" device. Image from Chung et al and Samsung
To create a display that can undergo stretching and deformation without loss in performance, the researchers needed to ensure that all materials and elements, including the substrate, electrode, thin-film transistor, emission material layer, and sensor, were stretchable as well. To this end, the Samsung researchers chose to replace the plastic material in existing stretchable displays with an elastomer.
Elastomers are vulnerable to heat, and to mitigate this, the researchers physically altered the material’s thermal resistance by adjusting its molecular composition and chemically integrating certain molecule chains to establish a resistance to the materials used in semiconductor processes.
Further, using an “island structure,” the researchers could divert the experienced stresses away from the display and towards the elastomer, which minimized the stress sustained by the more fragile OLED pixel area.
A Flexible Future
Both Samsung and Stanford worked to tackle manufacturing challenges associated with flexible electronics, and both achieved seemingly impressive results.
While there are still many challenges towards flexible electronics, much progress is being made in academia, hopefully giving enough evidence that this technology could soon come to fruition.
Interested in other flexible electronic news? Catch up with the articles down below.