All Publications

  • Sono-optogenetics facilitated by a circulation-delivered rechargeable light source for minimally invasive optogenetics. Proceedings of the National Academy of Sciences of the United States of America Wu, X. n., Zhu, X. n., Chong, P. n., Liu, J. n., Andre, L. N., Ong, K. S., Brinson, K. n., Mahdi, A. I., Li, J. n., Fenno, L. E., Wang, H. n., Hong, G. n. 2019


    Optogenetics, which uses visible light to control the cells genetically modified with light-gated ion channels, is a powerful tool for precise deconstruction of neural circuitry with neuron-subtype specificity. However, due to limited tissue penetration of visible light, invasive craniotomy and intracranial implantation of tethered optical fibers are usually required for in vivo optogenetic modulation. Here we report mechanoluminescent nanoparticles that can act as local light sources in the brain when triggered by brain-penetrant focused ultrasound (FUS) through intact scalp and skull. Mechanoluminescent nanoparticles can be delivered into the blood circulation via i.v. injection, recharged by 400-nm photoexcitation light in superficial blood vessels during circulation, and turned on by FUS to emit 470-nm light repetitively in the intact brain for optogenetic stimulation. Unlike the conventional "outside-in" approaches of optogenetics with fiber implantation, our method provides an "inside-out" approach to deliver nanoscopic light emitters via the intrinsic circulatory system and switch them on and off at any time and location of interest in the brain without extravasation through a minimally invasive ultrasound interface.

    View details for DOI 10.1073/pnas.1914387116

    View details for PubMedID 31811026

  • How is flexible electronics advancing neuroscience research? Biomaterials Chen, Y., Rommelfanger, N. J., Mahdi, A. I., Wu, X., Keene, S. T., Obaid, A., Salleo, A., Wang, H., Hong, G. 2020; 268: 120559


    Innovative neurotechnology must be leveraged to experimentally answer the multitude of pressing questions in modern neuroscience. Driven by the desire to address the existing neuroscience problems with newly engineered tools, we discuss in this review the benefits of flexible electronics for neuroscience studies. We first introduce the concept and define the properties of flexible and stretchable electronics. We then categorize the four dimensions where flexible electronics meets the demands of modern neuroscience: chronic stability, interfacing multiple structures, multi-modal compatibility, and neuron-type-specific recording. Specifically, with the bending stiffness now approaching that of neural tissue, implanted flexible electronic devices produce little shear motion, minimizing chronic immune responses and enabling recording and stimulation for months, and even years. The unique mechanical properties of flexible electronics also allow for intimate conformation to the brain, the spinal cord, peripheral nerves, and the retina. Moreover, flexible electronics enables optogenetic stimulation, microfluidic drug delivery, and neural activity imaging during electrical stimulation and recording. Finally, flexible electronics can enable neuron-type identification through analysis of high-fidelity recorded action potentials facilitated by its seamless integration with the neural circuitry. We argue that flexible electronics will play an increasingly important role in neuroscience studies and neurological therapies via the fabrication of neuromorphic devices on flexible substrates and the development of enhanced methods of neuronal interpenetration.

    View details for DOI 10.1016/j.biomaterials.2020.120559

    View details for PubMedID 33310538

  • A wearable helical organic-inorganic photodetector with thermoelectric generators as the power source JOURNAL OF MATERIALS CHEMISTRY C Sa, C., Xu, X., Wu, X., Chen, J., Zuo, C., Fang, X. 2019; 7 (42): 13097–103

    View details for DOI 10.1039/c9tc04696h

    View details for Web of Science ID 000494705100009

  • Mode-splitting based optofluidic sensing at exceptional points in tubular microcavities OPTICS COMMUNICATIONS Wang, Y., Li, S., Kiravittaya, S., Wu, X., Wu, K., Li, X., Mei, Y. 2019; 446: 128–33
  • Ultrathin Silicon Nanomembrane in a Tubular Geometry for Enhanced Photodetection ADVANCED OPTICAL MATERIALS Xu, C., Pan, R., Guo, Q., Wu, X., Li, G., Huang, G., An, Z., Li, X., Mei, Y. 2019
  • Rolled-up Nanotechnology: Materials Issue and Geometry Capability ADVANCED MATERIALS TECHNOLOGIES Xu, C., Wu, X., Huang, G., Mei, Y. 2019; 4 (1)
  • Infrared tubular microcavity based on rolled-up GeSn/Ge nanomembranes. Nanotechnology Wu, X. n., Tian, Z. n., Cong, H. n., Wang, Y. n., Edy, R. n., Huang, G. n., Di, Z. n., Xue, C. n., Mei, Y. n. 2018; 29 (42): 42LT02


    Germanium-Tin (GeSn) alloys have attracted great amounts of attention as these group IV semiconductors present direct band-gap behavior with high Sn content and are compatible with current complementary metal oxide semiconductor technology. In this work, three dimensional tubular GeSn/Ge micro-resonators with a diameter of around 7.3 μm were demonstrated by rolling up GeSn nanomembranes (NM) grown on a Ge-on-insulator wafer via molecular beam epitaxy. The microstructural properties of the resonators were carefully investigated and the strain distributions of the rolled-up GeSn/Ge microcavities along the radial direction were studied by utilizing micro-Raman spectroscopy with different excitation laser wavelengths. The values of the strains calculated from Raman shifts agree well with the theoretical prediction. Coupled with fiber tapers, as-fabricated devices present a high quality factor of up to 800 in the transmission spectral measurements. The micro-resonators fabricated via rolled-up nanotechnology and GeSn/Ge NMs in this work may have great potential in photonic micro- and nanodevices.

    View details for DOI 10.1088/1361-6528/aad66e

    View details for PubMedID 30052202