Photo-attachment of biomolecules for miniaturization on wicking Si-nanowire platform.

We demonstrated the surface functionalization of a highly three-dimensional, superhydrophilic wicking substrate using light to immobilize functional biomolecules for sensor or microarray applications. We showed here that the three-dimensional substrate was compatible with photo-attachment and the performance of functionalization was greatly improved due to both increased surface capacity and reduced substrate reflectivity. In addition, photo-attachment circumvents the problems induced by wicking effect that was typically encountered on superhydrophilic three-dimensional substrates, thus reducing the difficulty of producing miniaturized sites on such substrate. We have investigated various aspects of photo-attachment process on the nanowire substrate, including the role of different buffers, the effect of wavelength as well as how changing probe structure may affect the functionalization process. We demonstrated that substrate fabrication and functionalization can be achieved with processes compatible with microelectronics processes, hence reducing the cost of array fabrication. Such functionalization method coupled with the high capacity surface makes the substrate an ideal candidate for sensor or microarray for sensitive detection of target analytes.

Gallium-doped tin oxide nano-cuboids for improved dye sensitized solar cell.

Tin dioxide (SnO2) is a potential candidate to replace conventional titanium dioxide (TiO2) in dye-sensitized solar cells (DSSCs) because of its wider bandgap and higher electron mobility. However, SnO2 suffers from low band edge that causes severe backflow of electrons towards electrolyte (charge recombination). Herein, we demonstrate that gallium (Ga) doping can increase the band edge of SnO2, and we show that DSSCs using a Ga-doped SnO2 nano-cuboids based photoanode offer improved open circuit potential (~0.74 V), fill factor (~73.7%), and power conversion efficiency (~4.05%).

Highly sensitive miniature photonic crystal fiber refractive index sensor based on mode field excitation.

A highly sensitive miniature photonic crystal fiber refractive index sensor based on field mode excitation is presented. The sensor is fabricated by melting one end of a photonic crystal fiber into a rounded tip and splicing and collapsing the other end with a single-mode fiber. The rounded tip is able to induce cladding mode excitation, which resulted in an additional phase delay. Linear response of 262.28 nm/refractive index unit in the refractive index range of 1.337 to 1.395 is obtained for the physical length of a 953 µm sensor. The sensor is also shown to be insensitive to environmental temperature.