• Home
• Agenda
• Registration
• Call For Presentations
• Information For Presenters
• Sponsors
• Travel Information
• Lodging
• On-Campus Parking & Transportation
• Optional Social Events
• Contact Information

Agenda

15:00–16:20 - Session 8: Nanostructures for Computing & Sensing

Professor Yeau-Ren Jeng (National Chung Cheng University), Chair

• 15:00–15:20
  Ferroelectric Micro- and Nanophotonic Structures and Devices
  Andy Kung ^1,2 and Lung-Han Peng ^{3
  1}Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei
  ²Department of Photonics, National Chiao-Tung University, Hsinchu
  ³Institute of Electro-Optical Engineering, National Taiwan University, Taiepi
  
  We report on the observation of single-mode stimulated bandedge emission from optically pumped prism-shaped gallium nitride (GaN) submicron-cavities. These cavities are fabricated by reaction-rate limited photo-chemical etching that preserves the non-polar {101–0} or {112–0} facets. The cavities are characterized to have an average quality factor of 103 and facet reflectivity exceeding 99%, allowing field-amplification due to repeated reflections in the transverse plane and field-polarization along the c axis. The demonstrated Q of this cavity is comparable to the state-of-the-art GaN nano-ring structure that has required sophisticated manipulation to fabricate.

  PPLT is a ferroelectric material that has promise of efficient wavelength conversion to the blue and uv regions. We have fabricated 2D quasi-phase-matched structures using PPLT and demonstrated efficient (>30%) SHG to the red, green, and blue wavelengths with these structures. We have also demonstrated a near-room temperature visible parametric oscillator capable of emitting 1W average power. This leads to the design and construction of a monolithic white light source that could have unity pump to white light conversion efficiency.

• 15:20–15:40
  Self-assembly of micro-retroreflectors
  Steven M. Kemper¹, Kaajal D. Shah¹, Tim Sherlock², Paul Ruchhoeft²,†, Robert L. Atmar³, and Richard C. Willson1,⁴,‡
  ¹Dept. of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204-4005
  ²Dept. of Electrical and Computer Engineering, University of Houston, Houston, TX 77204-4005
  ³Dept. of Molecular Virology & Microbiology, Baylor College of Medicine, Houston, TX 77030
  ⁴Dept. of Biochemical & Biophysical Sciences, University of Houston, Houston, TX 77204-4005
  
  Modern bioanalytical technologies, ranging from DNA probe array monitoring of mRNA expression to immunoassays for clinical diagnosis and biodefense, rely upon labels attached to biomolecules to make them easily detectable. Currently, the most common labels are fluorescent dyes, which emit a known wavelength of light when excited by shorter-wavelength radiation. Although extremely useful and well developed, such systems can suffer from low signal strength, low signal to noise ratios, low quantum efficiency, and photobleaching.

  We are developing a new and potentially superior label system based upon corner-cube micro-retroreflectors. Such retroreflectors consist of transparent cubes with three mirrored surfaces and return incident radiation directly back its source, making them extremely detectable. In fact, a set of corner-cube retroreflectors on the lunar surface is routinely detected and ranged as part of ongoing experiments on lunar orbital dynamics. Miniaturizing such a system would allow for the fabrication of labels with potentially superior performance in immunoassay, cell sorting, and microarray applications.

  Currently, we fabricate micron-sized corner cubes on glass silicon wafers where one of the three reflective surfaces is decorated with antibodies that capture the target molecule. Gold nanoparticles, also decorated with anti-target antibodies, assemble on the surface in the presence of the target molecule and substantially reduce the surface reflectivity at specific wavelengths. Because the surface area is very low (tens of square microns), the device sensitivity is potentially very high. We are currently addressing the rapid detection of Norwalk virus in collaboration with researchers from the Baylor College of Medicine.

• 15:40–16:00
  Nano-Fabrication assisted by x-rays
  Yeukuang Hwu
  Institute of Physics, Academia Sinica, Nankang, 11529, Taiwan
  
  Assisted by the high coherence of synchrotron X-rays, phase contrast due to the difference in the refractive index is added to the absorption as another, yet much improved, contrast mechanism. Together with the improvement in the detecting system, we can now looking deep inside into matters with unprecedented precision and speed. Sub-μm or better resolution radiograph can now be obtained with ease and in many cases fast phenomenon can be observed with time resolution better than tens of microsecond. Ongoing developments in the instrumentation and reconstruction algorithms have generated higher excitement with the recent demonstration of 30nm scale resolution in 3D.

  The intense x-rays are also used to fabricate nanostructures, mostly by x-ray lithography and LIGA techniques. The similar x-ray-induced chemical reactions can also be used to synthesize nanoparticles of metals, oxides and polymers with great efficiency and control. These previously unknown capabilities of x-rays now open the door to a number of new therapeutical methods which relies on x-ray targeted drug release, enhanced x-ray radiotherapy and microbeam therapy. These new therapeutical strategy might be relevant human health in the near future. Together with the much better know capability of x-ray in characterization—x-ray diffractions, x-ray absorption spectroscopy, a short review of x-ray technology will address specifically its application to various domains in science, the relevance to the medicine, nano-science and -technology.

• 16:00–16:20
  Nerve Agent and Chemical Sensing Using Nanostructured Crosslinked Dendrimeric Precursors
  Rigoberto Advincula
  Department of Chemistry and Department of Chemical Engineering, University of Houston, Houston, TX 77204-5003
  
  This work describes the use of nanostructured conjugated crosslinked polymer materials based on PAMAM dendrimer precursors that have very high selectivity and sensitivity for toxic nerve agents. These nerve agents based on organo-phosphate derivatives such as sarin and soman are highly toxic and yet can be practically indistinguishable from organophosphate fertilizer derivatives in terms of chemical identification. By using electrochemically crosslinked dendrimer precursors with carbazole peripheral groups, highly sensitive and selective sensing was achieved using a surface plasmon resonance technique (SPR) on nerve agent analogs. The sensitivity was found to be from nanomolar to picomolar values. The nanostructure of the ultrathin films was achieved by a carefully controlled dendrimer design as well as the incorporation of Cu++ ions together with a self-assembled monolayer (SAM) modified substrate. The possibilities for using nanopatterned substrates will be demonstrated. The importance of material nanostructure and composition parameters is emphasized.