DLC/TiNi microcage for biopsy applications

A TiNi/diamond-like-carbon (DLC) microcage for biological application has been designed, fabricated and characterized. A compressively stressed DLC film with TiNi pattern on top lifts the fingers upwards once they are released from the substrate, and the microcage can be closed through shape memory effect of top TiNi film with temperature below 80°C. Further heating above 100°C, the gradual opening of the microcage can be obtained due to thermal bimorph effect. The biocompatibility of both the TiNi and DLC films has been proved using a cell-culture method.

Ultrasound elastography as an adjuvant to conventional ultrasound in the preoperative assessment of axillary lymph nodes in suspected breast cancer: a pilot study.

AIMS: To compare the performance of ultrasound elastography with conventional ultrasound in the assessment of axillary lymph nodes in suspected breast cancer and whether ultrasound elastography as an adjunct to conventional ultrasound can increase the sensitivity of conventional ultrasound used alone. MATERIALS AND METHODS: Fifty symptomatic women with a sonographic suspicion for breast cancer underwent ultrasound elastography of the ipsilateral axilla concurrent with conventional ultrasound being performed as part of triple assessment. Elastograms were visually scored, strain measurements calculated and node area and perimeter measurements taken. Theoretical biopsy cut points were selected. The sensitivity, specificity, positive predictive value (PPV), and negative predictive values (NPV) were calculated and receiver operating characteristic (ROC) analysis was performed and compared for elastograms and conventional ultrasound images with surgical histology as the reference standard. RESULTS: The mean age of the women was 57 years. Twenty-nine out of 50 of the nodes were histologically negative on surgical histology and 21 were positive. The sensitivity, specificity, PPV, and NPV for conventional ultrasound were 76, 78, 70, and 81%, respectively; 90, 86, 83, and 93%, respectively, for visual ultrasound elastography; and for strain scoring, 100, 48, 58 and 100%, respectively. There was no significant difference between any of the node measurements CONCLUSIONS: Initial experience with ultrasound elastography of axillary lymph nodes, showed that it is more sensitive than conventional ultrasound in detecting abnormal nodes in the axilla in cases of suspected breast cancer. The specificity remained acceptable and ultrasound elastography used as an adjunct to conventional ultrasound has the potential to improve the performance of conventional ultrasound alone.

Hygroscopic biomimetic transducers made from CNT-hydrogel composites

Plants as well as other biological organisms achieve directed movements by fibres that constraint and direct the isotropic expansion of a matrix material. In order to mimic these actuators, complex arrangements of rigid fibres must be achieved, which is challenging, especially at small scales. In this paper, a new method to organize carbon nanotubes (CNTs) into complex shapes is employed to create a framework for hydrogel infiltration. These CNT frameworks can be realized as iris, needle and bridge architectures, and after hydrogel infiltration, they show directed actuation in response to water uptake. Finally, we show how the latter can be employed as a novel hygroscopic sensor. © 2011 IEEE.

Thermal annealing effect on the nanomechanical properties and structure of P3HT:PCBM thin films

Nanostructured polymer-fullerene thin films are among the most prominent materials for application in high efficient polymer solar cells. Specifically, poly(3-hexylthiophene) (P3HT) and fullerene derivatives (PCBM) blends are used as the donor/acceptor materials forming a bulk heterojunction. Although P3HT:PCBM properties have been extensively studied, less light has been set on its nanomechanical properties, which affect the device service life. In this work Atomic Force Acoustic Microscopy (AFAM), Atomic Force Spectroscopy and Nanoindentation were used to study the effect of the fullerene presence and the annealing on the P3HT:PCBM nanomechanical behavior. The P3HT:PCBM thin films were prepared by spin coating on glass substrates and then annealed at 100 °C and 145 °C for 30 min. Large phase separation was identified by optical and Atomic Force Microscopy (AFM) for the annealed samples. Needle-like PCBM crystals were formed and an increase of the polymer crystallinity degree with the increase of the annealing temperature was confirmed by X-ray diffraction. AFAM characterization revealed the presence of aggregates close to stiff PCBM crystals, possibly consisting of amorphous P3HT material. AFM force-distance curves showed a continuous change in stiffness in the vicinity of the PCBM crystals, due to the PCBM depletion near its crystals, and the AFM indentation provided qualitative results about the changes in P3HT nanomechanical response after annealing. © 2011 Elsevier B.V. All rights reserved.

Devitrite-based optical diffusers.

Devitrite is a novel material produced by heat treatment of commercial soda-lime-silica glass. It consists of fans of needle-like crystals which can extend up to several millimeters and have interspacings of up to a few hundred nanometers. To date, only the material properties of devitrite have been reported, and there has been a distinct lack of research on using it for optical applications. In this study, we demonstrate that randomly oriented fans of devitrite crystals can act as highly efficient diffusers for visible light. Devitrite crystals produce phase modulation of light because of their relatively high anisotropy. The nanoscale spacings between these needles enable light to be diffused to large scattering angles. Experimentally measured results suggest that light diffusion patterns with beam widths of up to 120° are produced. Since devitrite is an inexpensive material to produce, it has the potential to be used in a variety of commercial applications.