23-03-2021 | | By Sam Brown
Recently, researchers from China have demonstrated a fabric with an integrated display that can be worn, washed, and dried multiple times. What challenges do wearable electronics face, how has the Chinese research group developed a wearable display, and how can it be used in future applications?
Depending on who you ask, wearable electronics either already exist or are yet to exist. This is because many cannot agree on what the term “wearable electronics” really means. Some would say that devices such as smartwatches count as wearable electronics, while others would argue that something can only be considered wearable if it is worn like a piece of clothing and thus has clothing properties. Therefore, we will distinguish the two by calling smartwatches and other ridged designs “worn electronics” and electronics integrated into clothes as wearable electronics.
One of the biggest challenges faced by wearable electronics is that for something to be wearable (e.g. clothes), it must be comfortable to wear, move with the body, and potentially be washable. However, everyday electronics could not be further from these requirements; they are bulky, heavy, ridged, and cannot get wet in most cases.
While wearable electronics can be constructed to some degree (i.e. integrating sensors and ICs into clothing), such designs rarely survive multiple washes and often break when folded. The wearable electronics industry is still non-existent, but many thousands of researchers worldwide try to solve the many problems of wearable electronics using flexible electronics, printed electronics, thin films, and wires.
For wearable electronics to become practical, they need to provide users with feedback, whether it be a Bluetooth connection to a smartphone or LED indicators to show some status or reading. However, it could be argued that the holy grail of wearable electronics would come in the form of a fully functioning display.
Displays are extremely effective at providing feedback as they can draw graphics and text which are far more user friendly. However, display technologies are almost always ridged in design with multiple layers that work together and, as such, cannot be used in wearable electronics. Flexible OLED displays do exist, but even then, these are sensitive devices that provide minimal comfort when worn and do not often survive being washed.
However, recently researchers from China have been able to develop an entire fabric display that not only folds and breathes like standard material but can be washed and dried multiple times and still survive. The new wearable display provides a fully interactive display that has the same brightness as a typical TV and has dimensions of 20 feet by 10 inches.
The display is constructed by weaving electrically conductive transparent fibres with luminescent threads into breathable cotton yarn. The fabric created has approximately 500,000 pixels with fibre spacing of around 800 microns (0.8mm), and pixels are formed where the luminescent fibres meet the conductive fibres.
The prototype device is not only more durable than flexible displays already being produced, but the display worked without floors after 1,000 cycles of bending, stretching, and pressing while also surviving 100 cycles of washing.
Another major development in the Chinese team's research is that not was the fabric demonstrated to function. It was then used in fully working prototypes to show how it can be used. The researchers used pieces of fabric to create an embedded display into a shirt that could be used to show images of maps, numbers, and graphics.
Image courtesy of Huisheng Peng's Group
The use of such technology has many applications in multiple fields, and one, in particular, that was shown by the team was wrist-worn navigation. Motorcycle users can sometimes struggle to use navigation systems as they are exposed to the weather, and looking down to see a navigation system can be dangerous. However, the team showed that a wrist-worn navigation system would be resistant to the elements and provide a better option for riders.
The same technology could be used in dangerous work environments such as industrial sites. It is increasingly required for maintenance and repairers to use tablets and computing systems to get information from processing equipment and manuals. This can lead to difficulty if the tablet cannot be mounted safely for the users to view. Instead, a wrist-worn display would allow users to safely use tools while seeing the display, essentially freeing up workspace and hands.
Scientific papers and announcements on so-called “breakthroughs” come out often, and in many cases, they are often disappointing either because they exaggerate their claims or do not have any practical use. However, the demonstration of this fabric display can truly be a breakthrough as it potentially solves the issue with displays in wearable electronics. Still, it has even shown working examples of a display embedded into clothing.