Apr
15

Drexel 2013 Teaching Excellence Award and Graduate Spirit Award for Cheng-Hsin Lu

Drexel Teaching Excellence Award 2013

Cheng-Hsin (Johnson) Lu has received “Teaching Excellence Award – Highly Commended” and “Graduate Spirit Award” on Drexel University Graduate Student Day Award 2013.

Graduate Student Day Award Winners 2013

Sep
27

Published Paper Highlighted in nanotechweb.org

Chun-Yi Hsieh, Meng-Lin Lu, Ju-Ying Chen, Yung-Ting Chen, Yang-Fang Chen, Wan Y Shih and Wei-Heng Shih’s latest paper published in Nanotechnology, titled “Single ZnO nanowire–PZT optothermal field effect transistors” has been highlighted online in nanotechweb.org, titled “Ferroelectricity and light control current in new transistors.”

From the article: “Ferroelectric materials such as Pb(Zr0.3Ti0.7)O3 (PZT) with up and down remnant polarizations have been employed in non-volatile ferroelectric field effect memories as gate dielectrics. PZT is also pyroelectric, which means that the polarization properties can be modified with temperature. Inspired by this characteristic, researchers have fabricated a single ZnO nanowire (NW) field effect transistor (FET) on a PZT substrate. The team found that the drain current in a single ZnO NW could be modulated by an optothermal gating mechanism using PZT as the gate dielectric. Furthermore, the scientists obtained a maximum current sensitivity of 25 nA/mW for down polarization at a drain field of 83 kV/m, which is about three orders of magnitude higher than the typical 20 nA/W at a drain field of 50 kV/m for photogating transistors based on a carbon nanotube on SiO2/Si substrate architecture.”

The full article can be viewed directly here on nanotechweb.org .

Sep
27

Paper Published in Nanotechnology

Chun-Yi Hsieh, Meng-Lin Lu, Ju-Ying Chen, Yung-Ting Chen, Yang-Fang Chen, Wan Y Shih and Wei-Heng Shih’s latest paper, titled “Single ZnO nanowire–PZT optothermal field effect transistors” has been published online in Nanotechnology.

From the abstract: “A new type of pyroelectric field effect transistor based on a composite consisting of single zinc oxide nanowire and lead zirconate titanate (ZnO NW–PZT) has been developed. Under infrared (IR) laser illumination, the transconductance of the ZnO NW can be modulated by optothermal gating. The drain current can be increased or decreased by IR illumination depending on the polarization orientation of the Pb(Zr0.3Ti0.7)O3 (PZT) substrate.
Furthermore, by combining the photocurrent behavior in the UV range and the optothermal gating effect in the IR range, the wide spectrum of response of current by light offers a variety of opportunities for nanoscale optoelectronic devices.”

The paper can be viewed directly here. [View PDF]

Jul
27

Paper Published in IEEE Transactions on Industrial Electronics

Xiaotong Gao, Wei-Heng Shih and Wan Y. Shih’s latest paper, titled “Flow Energy Harvesting Using Piezoelectric Cantilevers with Cylindrical Extension,” has been published online in IEEE Transactions on Industrial Electronics.

From the abstract: “We present a new piezoelectric flow energy harvester (PFEH) based on a piezoelectric cantilever with a cylindrical extension. The flow induced vibration of the cylindrical extension causes the piezoelectric cantilever to vibrate at the natural frequency of the PFEH. The PFEH provides a low-cost, compact and scalable power source for small electronics by harvesting energy from ambient flows such as wind and water streams. Prototypes were tested in both laminar and turbulent air flows demonstrating the feasibility of the design. Turbulence excitation was found to be the dominant driving mechanism of the PFEH with additional vortex shedding excitation contribution in the lock-in region.”

The paper can be viewed directly here. [View PDF]

Jul
27

Paper Published in Nanotechnology

Giang H T Au, Wan Y Shih, S-Ja Tseng and Wei-Heng Shih’s latest paper, titled “Aqueous CdPbS quantum dots for near-infrared imaging,” has been published online in Nanotechnology.

From the abstract: “Quantum dots (QDs) are semiconducting nanocrystals that have photoluminescent (PL) properties brighter than fluorescent molecules and do not photo-bleach, ideal for in vivo imaging of diseased tissues or monitoring of biological processes. Near-infrared (NIR) fluorescent light within the window of 700–1000 nm, which is separated from the major absorption peaks of hemoglobin and water, has the potential to be detected several millimeters under the surface with minimal interference from tissue autofluorescence. Here we report the synthesis and bioimaging demonstration of a new NIR QDs system, namely, CdPbS, made by an aqueous approach with 3-mercaptopropionic acid (MPA) as the capping molecule. The aqueous-synthesized, MPA-capped CdPbS QDs exhibited an NIR emission in the range of 800–950 nm with xi ≥ 0.3, where xi denotes the initial Pb molar fraction during the synthesis. Optimal PL performance of the CdPbS QDs occurred at xi = 0.7, which was about 4 nm in size as determined by transmission electron microscopy, had a rock salt structure and a quantum yield of 12%. Imaging of CdPbS QDs was tested in membrane staining and transfection studies. Cells transfected with CdPbS QDs were shown to be visible underneath a slab of chicken muscle tissue of up to 0.7 mm in thickness without the use of multiple-photon microscopy.”

The paper can be viewed directly here. [View PDF]

Jul
27

Paper Published in Applied Physics Letters

Chun-Yi Hsieh, Yung-Ting Chen, Wei-Jyun Tan, Yang-Fang Chen, Wan Y. Shih, and Wei-Heng Shih’s latest paper, titled “Graphene-lead zirconate titanate optothermal field effect transistors,” has been published online in Applied Physics Letters.

From the abstract: “We have developed a pyroelectric field effect transistor (FET) based on a graphene-lead zirconate titanate (PZT) system. Under the incidence of a laser beam, the drain current can be increased or decreased depending on the direction of the polarization of the PZT substrate. The drain current sensitivity of the optothermal FET can reach up to 360 nA/mW at a drain field of 6.7 kV/m more than 5 orders of magnitude higher than that of the photogating transistors based on carbon nanotube on SiO2/Si substrate. Graphene is an excellent component for pyroelectric FET due to its high optical transparency and conductance.”

The paper can be viewed directly here. [View PDF]

Jul
27

Drexel Research Day 2012 poster award for Giang Au

Drexel Research Day 2012

The winner of the poster award for graduate student in Biology and Biomedical category is Assessing Breast Cancer Margin Using an Aqueous Quantum Dot (AQDs) Enabled Molecular Probe. The author is Giang Au and co-authors are Linette Mejias, Vanlila K. Swami, and Ari D. Brooks. Advisors are Dr. Wan Y. Shih and Dr. Wei-Heng Shih.


Jul
27

Paper Published in Analytical Chemistry

LiNa Loo, Joseph A. Capobianco, Wei Wu, Xiaotong Gao, Wan Y. Shih, Wei-Heng Shih, Kambiz Pourrezaei, Matthew K. Robinson, and Gregory P. Adams’s latest paper, titled “Highly Sensitive Detection of HER2 Extracellular Domain in the Serum of Breast Cancer Patients by Piezoelectric Microcantilevers,” has been published online in Analytical Chemistry.

From the abstract: “Rapid and sensitive detection of serum tumor biomarkers are needed to monitor cancer patients for disease progression. Highly sensitive piezoelectric microcantilever sensors (PEMS) offer an attractive tool for biomarker detection; however, their utility in the complex environment encountered in serum has yet to be determined. As a proof of concept, we have functionalized PEMS with antibodies that specifically bind to HER2, a biomarker (antigen) that is commonly overexpressed in the blood of breast cancer patients. The function and sensitivity of these anti-HER2 PEMS biosensors was initially assessed using recombinant HER2 spiked into human serum. Their ability to detect native HER2 present in the serum of breast cancer patients was then determined. We have found that the anti-HER2 PEMS were able to accurately detect both recombinant and naturally occurring HER2 at clinically relevant levels (>2 ng/mL). This indicates that PEMS-based biosensors provide a potentially effective tool for biomarker detection.”

The paper can be viewed directly here. [View PDF]

Jul
27

Paper Published in IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

Xiang Li, Wei Wu, Youngsoo Chung, Wan Y. Shih, Wei-Heng Shih, Qifa Zhou, and K. Kirk Shung’s latest paper, titled “80-MHz Intravascular Ultrasound Transducer Using PMN-PT Free-Standing Film,” has been published online in IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control.

From the abstract: “[Pb(Mg1/3Nb2/3)O3]0.63[PbTiO3]0.37 (PMN-PT) free-standing film of comparable piezoelectric properties to bulk material with thickness of 30 μm has been fabricated using a modified precursor coating approach. At 1 kHz, the dielectric permittivity and loss were 4364 and 0.033, respectively. The remnant polarization and coercive field were 28 μ C/cm2 and 18.43 kV/cm. The electromechanical coupling coefficient kt was measured to be 0.55, which was close to that of bulk PMN-PT single-crystal material. Based on this film, high-frequency (82 MHz) miniature ultrasonic transducers were fabricated with 65% bandwidth and 23 dB insertion loss. Axial and lateral resolutions were determined to be as high as 35 and 176 μ m. In vitro intravascular imaging on healthy rabbit aorta was performed using the thin film transducers. In comparison with a 35-MHz IVUS transducer, the 80-MHz transducer showed superior resolution and contrast with satisfactory penetration depth. The imaging results suggest that PMN-PT free-standing thin film technology is a feasible and efficient way to fabricate very-high-frequency ultrasonic transducers.”

The paper can be viewed directly here. [View PDF]

Jul
27

Paper Published in Journal of Nanoscience and Nanotechnology

Hui Li, Mengyan Li, Wan Y. Shih, Peter I. Lelkes, and Wei-Heng Shih’s latest paper, titled “Cytotoxicity Tests of Water Soluble ZnS and CdS Quantum Dots,” has been published online in Journal of Nanoscience and Nanotechnology.

From the abstract: “Cytotoxicity tests of zinc sulfide (ZnS) and cadmium sulfide (CdS) quantum dots (QDs) synthesized via all-aqueous process with various surface conditions were carried out with human endothelial cells (EA hy926) using two independent viability assays, i.e., by cell counting following Trypan blue staining and by measuring Alamar Blue (AB) fluorescence. The ZnS QDs with all four distinct types of surface conditions were nontoxic at both 1 µM and 10 µM concentrations for at least 6 days. On the other hand, the CdS QDs were nontoxic only at 1 µM, and showed significant cytotoxicity at 10 µM after 3 days in the cell counting assay and after 4 days in the AB fluorescence assay. The CdS QDs with (3-mercaptopropyl)trimethoxysilane (MPS)-replacement plus silica capping were less cytotoxic than those with 3-mercaptopropionic acid (MPA) capping and those with MPS-replacement capping. Comparing the results of ZnS and CdS QDs with the same particle size, surface condition and concentration, it is indicated that the cytotoxicity of CdS QDs and the lack of it in ZnS QDs were probably due to the presence and absence of the toxic Cd element, respectively. The nontoxicity of the aqueous ZnS QDs makes them favorable for in vivo imaging applications.”

The paper can be viewed directly here. [View PDF]

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