In this study, we proposed and fabricated optical sensor module integrated onto optical-electrical printed circuit board (PCB) for gas detection based on polymer waveguide with tin oxide thin film. Their potential application as gas sensors are confirmed through computational simulation using the two dimensional finite-difference time-domain method (2DFDTD). Optical-electrical PCB was integrated into vertical cavity surface emitting laser (VCSEL), photodiode and polymeric sensing device was fabricated by the nano-imprint lithography technique. SnO<sub>2</sub> thin film of 100nm thickness was placed on the surface of core layer exposed by removing the specific area of the upper cladding layer of 300 μm length and 50 μm width. The performance of the device was measured experimentally. Initial study on the sensor performance for carbon monoxide gas detection indicated good sensitivity.
In this study, Graphene patterns using laser-induced chemical vapor deposition (LCVD) with a visible CW laser (λ = 532 nm) irradiation at room temperature was investigated. Optically-pumped solid-state laser with a wavelength of 532 nm irradiates a thin nickel foil to induce a local temperature rise, thereby allowing the direct writing of graphene patterns about ~10 μm in width with high growth rate on precisely controlled positions. It is demonstrate that the fabrication of graphene patterns can be achieved with a single scan for each graphene pattern using LCVD with no annealing or preprocessing of the substrate. The scan speed reaches to about ~200 μm/s, which indicates that the graphene pattern with an unite area (10×10 μm) can be grown in 0.05 sec. The number of graphene layers was controlled by laser scan speed on a substrate. The fabricated graphene patterns on nickel foils were directly transferred to desired positions on patterned electrodes. The position-controlled transfer with rapid single-step fabrication of graphene patterns provides an innovative pathway for application of electrical circuits and devices.
We proposed new concepts on the development of intelligent biomedical microrobot using flagellated bacteria
Salmonella typhimurium which has various properties such as micro-actuators, micro-sensors, treatment and diagnosis of solid tumors. We fabricated a bacteria-based microrobot using attenuated Salmonella typhimurium for medical
applications. In addition, for motility enhancement of microrobots, we regulated the bacteria selective attachment on
microbead surfaces using the patterning methods through the submerged property of microbeads on agarose gel. Firstly, we fabricated bacteria-based microrobots using polystyrene (PS) microbeads which are treated with anti-bacterial adherent factors, such as O2 plasma or bovine serum albumin. The selective bacteria-attached PS microbead groups using O2 plasma or BSA are showed higher motility than untreated whole bacteria-attached PS microbead groups. Secondly, we fabricated bacteria-based microrobots using biocompatible materials, poly(ethylene glycol) (PEG). We regulate the bacteria selective attachment on PEG microbead surfaces using bacteria adhesion materials, poly-L-lysine (PLL). Similar with the bacteria-based microrobots using PS microbeads, the selective bacteria-attached PEG microbeads group through the PLL selective coating showed higher motility than PLL-uncoated and whole PLL-coated PEG microbeads groups. Therefore, we expected that the proposed fabrication methods of the bacteria-based microrobots could have the following characteristics such as the high efficiency using flagellated bacteria, the enhanced motility using the bacteria selective patterning, and the potential applicability to human body using the biocompatible materials.