This paper addresses the assay of collagenase activity using Light Addressable Amperometric Sensor (LAAS). The redox current of LAAS was reduced by deposited collagen layers and recovered by collagenase solution. The collagen layers on the LAAS is considered to be broken down by collagenase. We expect an application of LAAS to activity evaluation.
This work describes the way of sensing bacteria, Legionella by photogate-type fluorescence sensor. Photoirradiation time dependences of L. dumoffii with the UV-photointensity as a parameter was obtained by the optical sensor. The photocurrents obtained by the sensor decreased depending on the irradiation time, showing the decay process of fluorescent material in Legionella cells. Initial decay rates were also found to vary with UV-photointensity. These results indicate that the photogate-type optical sensor is able to detect Legionella by using a simple combination of photochemical reaction rate constant and the excitation light intensity.
A mirror is a key component of microcavity lasers. We developed a tunable laser with a microelectromechanical system (MEMS) movable mirror and a vertical cavity surface emitting laser (VCSEL), called MEMS-VCSEL. A concave shape for the MEMS mirror is fabricated to reduce diffraction loss by applying a chemical mechanical polishing process to the Si surface of a MEMS chip. Because the shape of the cavity in VCSELs affects the beam profile or the polarization of laser light, it should be evaluated quantitatively to investigate the characteristics of the laser. In this study, we demonstrate that the concave shape measured in three dimensions complies with Euler's theorem in differential geometry at the bottom area of the concave. The principal curvatures and directions of the MEMS mirror are estimated and revealed to agree with the actual concave shape. Our quantitative evaluation helps estimate not only the principal curvatures and directions, but also the normal curvature of the concave shape in any direction. These estimations are valuable for investigating the characteristics of MEMS-VCSELs such as the mode profile and the polarization state.
We report evaluation of thick-film positive photoresists for grayscale lithography. The target thickness of the photoresists is 10 to 20 µm, which is one the most popular range for micro structures. The precise direct laser writer, DWL 2000CE was utilized for the grayscale lithography. To evaluate the profile controllability of each photoresist by using dose correction, 256 grayscale slope pattern of 100 µm in length was fabricated on a glass substrate and measured by a confocal microscope. The dose correction realized liner relationship between grayscale value and residual thickness of the photoresists. By using an optimized data of the dose correction for each photoresist, 1024 grayscale microlens array pattern as a three-dimensional micro structure was successfully fabricated on a glass substrate. The fabrication error between the measured profile of one of the microlenses and the designed spherical profile of microlens of 80 µm in diameter and 16 µm in height was less than 0.2 µm within 10 µm from the center.