23-12-2020 | | By Sam Brown
Recently, a Japanese research team from Osaka University have created a transparent sensor that marks a significant breakthrough in the field of flexible, transparent devices. What is it that the team have developed, what applications could it be used in, and why is it so important?
Flexible electronics is a field of electronics that is in involved with making flexible electronics parts including components, connectors, and electronic substrates. While some flexible solutions are available to the market (such as flexible connectors used between different PCBs in LCDs), most electronics components are ridged in nature.
Ridged components themselves are ideal for the vast majority of applications whether it is large scale computing or a control circuit for a toaster. But electronics that need to be used in flexible environments such as wearable devices, and organic surfaces must be flexible themselves. A few components, such as automotive-grade SMD capacitors, are designed to have a small amount of flexibility, but only enough for tolerating vibration.
Researchers from Osaka University have developed a transparent sensor sheet that integrates electronic sensing capabilities. The transparent sheet utilises silver nanowires that not only provide electrical conductivity but are flexible and transparent (due to their nanoscale size).
One major improvement the researchers demonstrated is their ability to use high-resolution printing to create cross-aligned silver nanowire arrays all with reproducible features. The ability to print the nanowires with reliability and orientation is critical as traditional methods for using nanowires involve randomly oriented wires that alone cannot be used for many applications.
To demonstrate the capabilities of the sensor, they designed the sensor to detect electrophysiological signals from plants (i.e. detect electrical signals in plant leaves). The sensor was placed onto the leaf with a thickness of no more than 3 microns, and the transparent nature of the sheet allowed for the plant to continue absorbing light.
The sheet developed by the team shows promise in the role of nanowires in future electronics. The first major application for such electronics is head-up displays (HUDs). Typical HUDs require complex optics and projection systems that can be bulky and expensive. Such electronics would not only be able to conform to any shape surface. They would provide a display directly over the viewport. Thus, the need for complex headgear or project systems would not be required, and true HUDs could be fabricated.
The other major application for such sheets is wearable electronics. While the researchers have been advertising their development in transparent electronics, the ability for the sheet to conform to organic surfaces without damage is in itself a major step for flexible electronics. The ability of the sheet to act as a sensor while being flexible makes it ideal for worn medical sensors that read data from the skin.
According to the researchers, the transparent sheet also has applications in civil engineering and agriculture. Civil engineering projects could take advantage of such material by using it as a flexible strain gauge that could be wrapped around key structural parts. Agricultural industries could greatly benefit from transparent sensors by gathering data on light absorption and linking the data to plant productivity via AI.
While the sensor is still in its early days, the development by the Japanese team demonstrates a major breakthrough in transparent flexible electronics. If light-emitting devices can be incorporated into the sheet, then flexible transparent displays could easily be fabricated, and bring wearable electronics closer to reality.