• Bio-inspired flexible vibration visualization sensor based on piezo-electrochromic effect

    Journal of Materiomics [6:643-650 (2020)]
    Monitoring structural vibration can provide quantitative information for both structural health evaluations and early-warning maintenance. The most classic vibration-based structural health monitoring is equipped with piezoelectric accelerometers, which is expensive and inconvenient due to cumbersome and time-consuming sensor installation and high power-consumptive data acquisition systems. One other main challenge with these systems is the inherent limitations for multi-point monitoring in critical elements with curvature due to their non-conformability. Here, inspired by the chameleon, we report a cost-effective, flexible and conformal, self-powered vibration sensor based on elasto-electro-chemical synergistic effect of piezoelectricity and electrochromism. The sensor can provide not only in-situ visualization, but also ex-situ recording of structural vibration due to the non-volatile color memory effect of electrochromism. The passive sensor system is composed of two distinct electronic components — ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 piezoelectric single crystal ribbon sensors and a solid-state tungsten trioxide electrochromic indicator driven by vibration-induced voltage generated by the piezoelectric ribbons. The proposed piezo-electrochromic based passive non-volatile visualization sensor may find diverse applications in structural health monitoring, smart wallpapers, and medical injury rehabilitation.
  • Piezo-catalysis for nondestructive tooth whitening

    Nature Communications [11:1328 (2020)]
    The increasing demand for a whiter smile has resulted in an increased popularity for tooth whitening procedures. The most classic hydrogen peroxide-based whitening agents are effective, but can lead to enamel demineralization, gingival irritation, or cytotoxicity. Furthermore, these techniques are excessively time-consuming. Here, we report a nondestructive, harmless and convenient tooth whitening strategy based on a piezo-catalysis effect realized by replacement of abrasives traditionally used in toothpaste with piezoelectric particles. Degradation of organic dyes via piezo-catalysis of BaTiO3 (BTO) nanoparticles was performed under ultrasonic vibration to simulate daily tooth brushing. Teeth stained with black tea, blueberry juice, wine or a combination thereof can be notably whitened by the poled BTO turbid liquid after vibration for 3 hours. A similar treatment using unpoled or cubic BTO show negligible tooth whitening effect. Furthermore, the BTO nanoparticle-based piezo-catalysis tooth whitening procedure exhibits remarkably less damage to both enamel and biological cells.
  • 2018 Sino-Korea Workshop on Ferroelectric Materials and Their Applications

    October 19-22, 2018, Nanjing, Jiangsu, China
    The 2018 Sino-Korea Workshop on Ferroelectric Materials and Their Applications (SKWFMA-2018) has been held on October 19-22, 2018 in Nanjing, Jiangsu, China. More than 137 participants from Korea, China and US has been attent the workshop, including 60 invited talks and 33 poster presentations. SKWFMA-2018 is aimed to provide a forum to present and discuss the state-of-the-art developments in ferroelectric materials and their applications, including 1) Ferroelectric ceramics and device applications, and 2) Emergent ferroics and phenomenon, in order to provide a better understanding of the relationship between the multi-scale polar structures and macroscopic properties of ferroelectric materials and related phenomenon, and to design and synthesize novel ferroelectric materials of high-performance for technological applications.
  • Large piezoelectricity in ternary lead-free single crystals

    Advanced Electronic Materials [6(1):1900949, 2020]
    Since industry-standard piezoelectric materials contain toxic lead, such as lead zirconium titanate ceramics, a rapid surge in research on lead-free piezoelectric materials is occurring with regards to environmental safety and human health. Here, we report a ternary lead-free (Na0.5Bi0.5)TiO3-BaTiO3-(K0.5Na0.5)NbO3 single crystal with a large field induced strain of ~0.9% and a giant piezoelectric coefficient d33 of 840 pC N-1 at room temperature. Our results reveal that the electric field induced phase transition and phase boundary between energically comparable polar states (i.e., R3c and P4mm) plays an important role in achieving these ultrahigh piezoelectricity. Transmission electron microscopy and scan probe microscopy were employed to verify their weak-polar ferroelectric R3c and P4bm structure in the ground state. These unprecedentedly high piezoelectric properties make lead-free ternary single crystals leading candidate for piezoelectric-based device applications, especially towards the era of smart homes and implantable medical devices.
  • All-inorganic flexible piezoelectric energy harvester enabled by two-dimensional mica

    Nano Energy [43:351-358, 2018]
    A rapid surge in the research on self-powered bio-electronics is occurring toward the challenge that the state-of-the-art bio-devices require obsolete bulky batteries, which limit device miniaturization and lifespan. Among them, flexible piezoelectric materials that enable mechanical-to-electrical energy conversion, stimulate tremendous attraction to harvest mechanical energy from the motions of human and organs. Here, we report a cost-effective one-step process based on unique two-dimensional mica substrates to fabricate flexible piezoelectric energy harvesters, extending beyond prior art for all-inorganic flexible piezoelectric materials. As an exemplary demonstration, an all-inorganic, large scale, flexible piezoelectric Pb(Zr0.52Ti0.48)O3 energy harvester is fabricated with an outstanding performance (i.e., open-circuit voltage of 120 V, short-circuit current density of 150 μA cm-2 and power density of 42.7 mW cm-3), which are comparable to those via conventional “grow-transfer” technique from rigid substrates to organic soft ribbons, and are much greater by one to four orders of magnitude than previous reported ones based on piezoelectric nanofibers and organic thick films. In particular. This unique process provides a new perspective to fabricate all-inorganic piezoelectric energy harvesters for battery-free bio-electronics.
  • Phase transition in the near-surface region of ternary PIN-PMN-PT relaxor ferroelectric crystals

    Physics Review Applied [8:034032,2017]
    Relaxor ferroelectric single crystals have been documented to possess a skin effect in the near-surface region, which may play an important role in emerging micro-/nano-scale piezoelectric devices that are surface-dominated. Here, a metastable ferroelectric tetragonal phase is induced by an electric field applied above the Curie temperature (i.e., poling at high temperature) in rhombohedral structured PIN-PMN-PT ternary relaxor ferroelectric crystals. Most interestingly, this metastable tetragonal structure unexpectedly transforms into a monoclinic B-type (MB) phase, as revealed by reciprocal-space mesh scans via high-resolution x-ray diffraction. The domain configurations of the MB phase obtained by poling above the Curie temperature are similar to that obtained by poling at room temperature; however, the bulk piezoelectricity is extremely weak relative to that induced by the latter process. This controversy between microstructure and macro-property is understood by a “surface-interior” heterogeneous structure, which sheds insight into the existence of skin effects in the relaxor ferroelectric single crystals.
  • Magnetoelectrics for Magnetic Sensor Applications: Status, Challenges and Perspectives

    Materials Today [Invited Review, 17(6):269, 2014]
    The magnetoelectric (ME) effect, with cross-correlation coupling between magnetic and electric degrees of freedom, is associated with two promising application scenarios: magnetic field sensors and electric-write magnetic-read memory devices. In this review, we highlight recent progress in ME laminates for sensor applications, in particular with regards to the most difficult technical obstacle to their practical use (i.e., reduction of equivalent magnetic noise), while presenting an evolution of ME materials. The challenges and perspectives for the technical obstacles that would enable ME composites for sensor applications are emphasized.
  • An extremely low equivalent magnetic noise (~pT Hz-1/2) magnetoelectric sensor

    Advanced Materials (23:4111, 2011)
    In this communication, we present the realization of extremely low equivalent magnetic noise in a Metglas/piezofiber heterosturcture sensor through a combination of giant ME effects and a reduction in each of the internal sensor noise sources. An extremely low equivalent magnetic noise of 5.1 pT Hz-1/2 was found at 1Hz, which is very close to the predicted value of 4.2 pT Hz-1/2. In particular, the equivalent magnetic noise of the ME sensor unit was as low as about 1 pT Hz-1/2 at a frequency of only several Hz. The structure is comprised of six-layers of magnetostrictive Metglas and a piezoelectric core composite consisting of five PMN-PT fibers interrogated by a pair of Kapton? interdigited (ID) electrodes

About Us

  • 教授,博士生导师;
  • 江苏省“双创人才”;
  • 江苏省高等学校微课教学竞赛三等奖
  • 江苏省第十六批“六大人才高峰”B类
  • 美陶,Associate Editor

Welcome to our group! We are a research group on Advanced Sensing Materials and Devices in the School of Materials Science and Engineering, established in 2015 after Prof. Yaojin  Wang joint Nanjing University of Science and Technology. In our group, we unite fundamental materials science and device technology, in particular focus on: 1) Magneto-electronics and magnetic field sensors; 2) Flexible ferro-electronics for sensor and energy conversion devices towards artificial intelligence and Internet of Things; 3) Emergent piezo-based synergistic phenomenon and underlying physics. The research in our group is highly interdisciplinary, so we welcome ambious students from the field of physics, material science and electrical engineering to join our group.  欢迎对科研充满激情、对未来充满梦想的你加入我们这个具有朝气的研究团队,共谋发展、共创辉煌!优秀学生提供美国Pennstate University和香港理工PolyU等联合培养或访问机会。

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【Publication】Xuan Chen’s paper got accepted by Journal of Materiomi2020-06-05
【Certification】Guest Editor of Special Issue for 《Sensor》2020-05-15
【Publication】Yang Wang’s paper got accepted by Nature Communication2020-02-13
【Conference】China-Russia Workshop on Magnetoelectric Materials and D2020-01-14
【Conference】The 5th International Conference on Advanced Electromate2019-11-06
【Conference】2019 Korea/China/Asian workshop on Ferroelectrics and fu2019-11-04
【Publication】Prof. Wang’s paper got accepted by Advanced Electronic2019-10-21
【Conference】The 11th China-Japan Symposium on Ferroelectric Material2019-09-29
【Conference】International Conference IEEE 3M-NANO 20192019-08-08
【Conference】The 2019 ISAF-ICE-EMF-IWPM-PFM Conference2019-07-20
【Seminar】Prof. Yaojin Wang was invited to deliver a talk in Shanghai2019-05-31


Yaojin Wang (汪尧进) Laboratory of Advanced Sensitive Materials and Devices
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Department of Materials Science and Engineering.Nanjing University of Science and Technology