With the aim of developing compact and sensitive immunoassay devices for point-of-care testing, we studied an electrochemical method by using continuous flow in a microchannel gold-linked electrochemical immunoassay (GLEIA) on a screen-printed carbon electrode. Conventional GLEIA is a useful method to detect low-level antigen in real samples, but it requires a long incubation time (∼1h) and milliliter-order reagent volumes for measurement. In this study, a screen-printed electrode was put into a microfluidic channel to study the microchannel effect on GLEIA. By limiting the diffusion volume during the pre-oxidation to oxidation step of GLEIA, we found that the sensitivity increased. Owing to the continuous flow in a microchannel, the antigen-antibody reaction was accelerated, resulting in a 10 min detection time. It was also effective in reducing the minimum volume of washing buffer required.

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This paper presents a cell stretching microdevice for in-situ observation of stretched cell. In a conventional cell stretching device, it was difficult to observe the initial and in-situ cellular response to stretching. The presented device consists of an elastic culture chamber and leaf springs by which uniaxial stretch is applied to the culture chamber. The device is produced by a micro three-dimensional structure fabrication process using multiple exposures to the photoresist. The device permits the observation of cellular responses to stretching in real time because it is made of transparent materials when observed by optical microscope. We demonstrated the fundamental characteristics of a microdevice, and observed the cellular response behavior by a fabricated microdevice. The amount of the culture chamber deformation was controlled by the amount of the stretching arm displacement. Also, we demonstrated the culture chamber during stretching was not deformed toward the optical axis. Moreover, in-situ observation of transition of the cellular calcium signaling response to stretching succeeded by optical microscopy using fabricated microdevice. These results indicated that this device can be used to observe and evaluate the initial cellular response and micro-strain field on a cell membrane during uniaxial stretching.

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This paper presents a cell compression stimulus microdevice intended to evaluate the real-time response of cells to compression stimuli. The presented device consists of cell inlet ports, a pressure inlet port, a gasket, microchannels, culture chambers, and a diaphragm on the culture chamber for applying compressive pressure to cells. Compression stimuli applied to the cells can be controlled by regulating the expansion of the diaphragm via a pressure control. The device permits the observation of cellular responses to compressive pressure in real time because it is made of transparent materials and stimulates the cells without deforming the cell culture surface, when observed by optical microscope. We observed the cellular deformation and response behavior using a fabricated microdevice in real time. The changes of intracellular calcium concentration before and after compressive stimuli were observed by the fabricated device. Also, the intracellular maximum strain part and strain distribution of a cell that received compression stimulus were clarified by FEM analysis. These results indicate the device is expected to clarify the cellular mechanoreceptor mechanisms and signal transduction pathways and facilitate the control of stem cell differentiation by a combination of the experimental results and FEM analysis results.

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Microwave application technologies such as microwave heating, microwave assisted chemistry, etc. are of the innovative green technologies. This paper proposes a chip-size structure for continuous microwave irradiation. It consists of a post-wall waveguide and a micro channel arranged among the metallic posts (pillars), and utilizes the 24.125GHz ISM band instead of the commonly used 2.45GHz ISM band to realize miniaturization. The micro channel can be embedded easily by using the gaps between the metallic posts of the post-wall waveguide, simultaneously keeping the microwave energy confined. For the input of microwave power, two types of the irradiation structure are designed. One is a structure with coaxial transmission line to post-wall waveguide transformer. The other is a structure with microstrip feed line. The temperature-time profiles of some solvents under microwave irradiation are examined numerically and experimentally with microwave power sources of about 1W.

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The localized surface plasmon resonance (LSPR)-based plasmonic chemical sensor for detection of aldehyde compounds was developed using gold-capped nanoparticle layer substrate. In this study, for detection of aldehyde compounds, 2-Nonenal which some research has associated with human body odor alterations during aging was choose as a target. For detection of 2-Nonenal, self-assembled monolayer (SAM) was formed on the gold-capped nanoparticle layer substrate surface using 2-Aminoethanethiol. The LSPR absorbance changes by the surrounding refractive index change that is attributed by the covalent binding between aldehyde group of 2-Nonenal and amino groups of 2-Aminoethanethiol were monitored. By using this chemical sensor, the LSPR absorbance change with 2-Nonenal concentrations could be observed.

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The electron beam lithography (EBL) pattern-based plasmonic crystal for excitation of localized surface plasmon resonance (LSPR) was fabricated. For evaluation of sensing characteristics, lattice-shaped plasmonic crystal with different pitch was fabricated using EBL. These plasmonic crystals shows the different LSPR optical characteristics (peak shift and absorbance strength change), and the high sensitivity (up to 564.1 nm/refractive index unit (RIU)) could be observed. Based on these characteristics, plasmonic crystal is applicable to high sensitive label-free chemical or bio sensors.

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