Innovation and Development

Micrometer-resolution Piezo-phototronic Pressure-imaging Chip is Developed

Emulation of human senses by electronic means has long been a grand challenge for artificial intelligence and is pivotal in the development of accessible and natural interfaces between man and machine. Different from those well-developed senses (seeing, hearing, smelling and tasting), touching remains stubbornly difficult to mimic, since touching emulation necessitates the development of high spatial-resolution, high-sensitive, fast response, and large size pressure sensor arrays. Prof. Wang Zhonglin and his team in Beijing Institute of Nanoenergy and Nanoscience (CAS) and Georgia Institute of Technology reported the first individual-nanowire light-emitting-diode (NW LED) based pressure/force sensor array for fast mapping of strain at a resolution better than 2.7 μm and pixel density of 6350 dpi, which is about three orders of magnitude higher than the demonstrated data in literature and far exceeding the resolution defined by human skin. Each pixel is a single n-ZnO nanowire/p-GaN LED, the emission intensity of which is sensitively depending on the local pressure/force/strain owing to the piezo-phototronic effect, which is about the use of the inner-crystal piezopotential as a “gate” voltage to tune/control the charge transport and recombination in optoelectronic processes. Instead of using the cross-bar electrodes for sequential data output, the pressure image is read out in parallel for all of the pixels at a response/recovery time-resolution of 90 ms. The output signal is electroluminescence light that is easy to be integrated with on-chip photonic technologies for fast data transmission, processing and recording. This may be a major step toward digital imaging of mechanical signals by optical means, with potential applications in smart robots, human-machine interfacing, touch pad technology, personalized signatures, bio-imaging and optical MEMS. This paper reports an important breakthrough for the first use of individual-nanowire light-emitting-diode (NW LED) based pressure/force sensor array for fast mapping of strain at a resolution that is 1000 times better than the recently reported result in literature. The mechanism is new in science and the technology application is huge. This work is published on Nature Photonics on Aug. 11, 2013. The corresponding author is Prof. Wang Zhonglin, who is chief scientist and president of Beijing Institute of Nanoenergy and Nanoscience (CAS), while the first author, Dr. Pan Caofeng, who is awarded “1000 talented youth program”, is a professor of this institute.