Walter Hu

Publications (60) View all

• Article: Performance Analysis of Si Nanowire Biosensor by Numerical Modeling for Charge Sensing

  Xinrong Yang, William R. Frensley, Dian Zhou, Wenchuang Hu
  IEEE Transactions on Nanotechnology 01/2012; 11(3):501-512. · 2.29 Impact Factor
• Article: Cell encapsulation and oxygenation in nanoporous microcontainers.

  Barjor Gimi, Joonbum Kwon, Li Liu, Yang Su, Krishnamurthy Nemani, Krutarth Trivedi, Yonghao Cui, Behroze Vachha, Ralph Mason, Wenchuang Hu, Jeong-Bong Lee
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  ABSTRACT: With strides in stem cell biology, cell engineering and molecular therapy, the transplantation of cells to produce therapeutic molecules endogenously is an attractive and achievable alternative to the use of exogenous drugs. The encapsulation of such cell transplants in semi-permeable, nanoporous constructs is often required to protect them from immune attack and to prevent their proliferation in the host. However, effective graft immunoisolation has been mostly elusive owing to the absence of a high-throughput method to create precisely controlled, high-aspect-ratio nanopores. To address the clinical need for effective cell encapsulation and immunoisolation, we devised a biocompatible cell-encapsulating microcontainer and a method to create highly anisotropic nanopores in the microcontainer's surface. To evaluate the efficacy of these nanopores in oxygenating the encapsulated cells, we engineered 9L rat glioma cells to bioluminesce under hypoxic conditions. The methods described above should aid in evaluating the long term survival and efficacy of cellular grafts.
  Biomedical Microdevices 08/2009; 11(6):1205-12. · 3.03 Impact Factor
• Source

  Available from: utsouthwestern.edu

  Article: Fabrication of polymeric nanorods using bilayer nanoimprint lithography.

  Fatih Buyukserin, Mukti Aryal, Jinming Gao, Wenchuang Hu
  Small 05/2009; 5(14):1632-6. · 8.35 Impact Factor
• Source

  Available from: Unnat Bhansali

  Article: The fabrication of high density nanochannel organic light emitting diodes with reduced charge spreading.

  K Trivedi, U S Bhansali, B Gnade, W Hu
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  ABSTRACT: This study reports fabrication and characterization of nanoscale organic light emitting diodes with reduced charge spreading. Nanoimprint lithography is used to make SU-8 nanochannels with approximately 90 degrees sidewalls into which N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) and tris-(8-hydroxyquinoline) aluminum (Alq3) are thermally evaporated, to avoid charge spreading. Micron grating devices are fabricated for comparison. Device characteristics show that performance is retained while scaling down to nanochannels, as no geometry dependent trend is observed. Surface potential microscopy (SPM) measurements reveal an identical periodic difference in surface potential for nanochannel and microscale grating devices. The SPM results, together with cross-sectional scanning electron microscopy observation of the physical separation of nanoscale organic light emitting diodes (OLEDs), indicate electrical separation and isolated light emission from nanoscale confined OLEDs with minimized charge spreading.
  Nanotechnology 10/2009; 20(40):405204. · 3.98 Impact Factor
• Source

  Available from: Walter Hu

  Article: Nano-confinement induced chain alignment in ordered P3HT nanostructures defined by nanoimprint lithography.

  Mukti Aryal, Krutarth Trivedi, Wenchuang Walter Hu
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  ABSTRACT: Control of polymer morphology and chain orientation is of great importance in organic solar cells and field effect transistors (OFETs). Here we report the use of nanoimprint lithography to fabricate large-area, high-density, and ordered nanostructures in conjugated polymer poly(3-hexylthiophene) or P3HT, and also to simultaneously control 3D chain alignment within these P3HT nanostructures. Out-of-plane and in-plane grazing incident X-ray diffraction were used to determine the chain orientation in the imprinted P3HT nanostructures, which shows a strong dependence on their geometry (gratings or pillars). Vertical chain alignment was observed in both nanogratings and nanopillars, indicating strong potential to improve charge transport and optical properties for solar cells in comparison to bulk heterojunction structure. For P3HT nanogratings, pi-pi stacking along the grating direction with an angular distribution of +/-20 degrees was found, which is favorable for OFETs. We propose the chain alignment is induced by the nanoconfinement during nanoimprinting via pi-pi interaction and hydrophobic interaction between polymer chain and mold surfaces.
  ACS Nano 10/2009; 3(10):3085-90. · 10.77 Impact Factor