Abstract-High-resolution electroluminescent imaging of pressure distribution using a piezoelectric nanowire LED array

• a, Schematic band diagram of a p-GaN/n-ZnO p–n junction before (black line) and after (red line) applying a compressive strain, where the dip created at the interface is due to the non-mobile, positive ionic charges created by the piezo phototronic effect.

• Caofeng Pan,
• Lin Dong,
• Guang Zhu,
• Simiao Niu,
• Ruomeng Yu,
• Qing Yang,
• Ying Liu
• & Zhong Lin Wang

• http://www.nature.com/nphoton/journal/v7/n9/full/nphoton.2013.191.html

Emulation of the sensation of touch through high-resolution electronic means could become important in future generations of robotics and human–machine interfaces. Here, we demonstrate that a nanowire light-emitting diode-based pressure sensor array can map two-dimensional distributions of strain with an unprecedented spatial resolution of 2.7 µm, corresponding to a pixel density of 6,350 dpi. Each pixel is composed of a single n-ZnO nanowire/p-GaN light-emitting diode, the emission intensity of which depends on the local strain owing to the piezo-phototronic effect. A pressure map can be created by reading out, in parallel, the electroluminescent signal from all of the pixels with a time resolution of 90 ms. The device may represent a major step towards the digital imaging of mechanical signals by optical means, with potential applications in artificial skin, touchpad technology, personalized signatures, bio-imaging and optical microelectromechanical systems.