Fabrication of sharp silicon arrays to wound Caenorhabditis elegans

ABSTRACTUnderstanding how animals respond to injury and how wounds heal remains a challenge. These questions can be addressed using genetically tractable animals, including the nematode Caenorhabditis elegans. Given its small size, the current methods for inflicting wounds in a controlled manner are demanding. To facilitate and accelerate the procedure, we fabricated regular arrays of pyramidal features (“pins”) sharp enough to pierce the tough nematode cuticle. The pyramids were made from monocrystalline silicon wafers that were micro-structured using optical lithography and alkaline wet etching. The fabrication protocol and the geometry of the pins, determined by electron microscopy, are described in detail. Upon wounding, C. elegans expresses genes encoding antimicrobial peptides. A comparison of the induction of antimicrobial peptide gene expression using traditional needles and the pin arrays demonstrates the utility of this new method.

Nano-Structured Silicon: Fabrication, Optical Property, Defect States and Device Application

We use two different methods to fabricate nanostructured silicon on the surface of C-Si: femtosecond laser etching (FLE) and deep reactive ion etching (DRIE) combined with plasma immersion ion implantation (PIII). Nanocone silicon arrays of dense and random distribution are obtained by FLE. Meanwhile, cylindroid silicon nanostructures of excellent regularity and uniform coverage are achieved by DRIE. These nanostructured silicon materials show a remarkable enhancement on absorptance at near-infrared wavelength. Moreover, the minority carriers lifetime measurement is also carried out to evaluate defect states caused by two etching processes and their influence on semiconductor physical effects. A Si-PIN photoelectronic detector with nanostructured silicon at the back surface exhibits high near-infrared responsivity. These novel results may have a potential application in near-infrared photoelectronic devices.

Comparative Performance and Model Agreement of Three Common Photovoltaic Array Configurations

Three grid-connected monocrystalline silicon arrays on the National Institute of Standards and Technology (NIST) campus in Gaithersburg, MD have been instrumented and monitored for 1 yr, with only minimal gaps in the data sets. These arrays range from 73 kW to 271 kW, and all use the same module, but have different tilts, orientations, and configurations. One array is installed facing east and west over a parking lot, one in an open field, and one on a flat roof. Various measured relationships and calculated standard metrics have been used to compare the relative performance of these arrays in their different configurations. Comprehensive performance models have also been created in the modeling software pvsyst for each array, and its predictions using measured on-site weather data are compared to the arrays' measured outputs. The comparisons show that all three arrays typically have monthly performance ratios (PRs) above 0.75, but differ significantly in their relative output, strongly correlating to their operating temperature and to a lesser extent their orientation. The model predictions are within 5% of the monthly delivered energy values except during the winter months, when there was intermittent snow on the arrays, and during maintenance and other outages.

One-step facile fabrication of controllable microcone and micromolar silicon arrays with tunable wettability by liquid-assisted femtosecond laser irradiation

Micro/nanostructured silicon surfaces are attracting more and more research attention because of the wide range of applications in optoelectronic devices, microelectronics, microfluidics, and biomedical devices.