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Microfluidics-based in situ Biological and Chemical Sensing - Towards Integrated and Real-time Measurement in Deep Sea -
Abstract
Microfluidics is one of the emerging technologies to achieve advanced biological and chemical sensing. A project to develop a series of microfluidics-based in situ measurement systems, named IISA (Integrated In Situ Analyzer)' is underway in author's group at IIS, University of Tokyo. In this talk, a basic concept and technologies of microfluidics will be presented along with some examples of USA devices and systems. The possibilities and future perspectives of this new technology towards integrated and real-time measurement will be discussed.
... Several in situ analyzers for iron, manganese, and other chemical elements (Provin et al., 2011;Okamura et al., 2004) and for biological parameters such as ATP and microbial gene have been practically used. Other systems use micro total analysis systems (µTAS) to miniaturize the entire system (Fujii and Fukuba, 2007). The chemical sensors include pH, ORP, hydrogen sulfide, and others that use electrodes (Prien, 2007). ...
We developed a new multi-water-sampling system, ANEMONE-11, for autonomous underwater vehicle and remotely operated underwater vehicle exploration. Water samples are continuously collected by the ANEMONE-11 sampler by an in situ water pump at 40 mL/min and are sent to a selection valve unit that consists of 128 valves connected to 40 mL sampling bottles (50 cm in length). Each valve in the unit is selected and opened at preprogrammed intervals. We also discuss the results of observations at a hydrothermal area in the Okinawa Trough.
The paper seeks to evaluate the policy process of advanced technology for underwater constructions (UCs), its safety and challenges for ocean regime creation in 21st century. The recent years developing advanced technology for UCs are highly appreciating for oceanic surveys, constructions, submarine cables and others with increasingly challenging and complex fields. With all of the concerns about the environment these days, developing advanced technologies can be useful tools to study and develop the current underwater conditions, no doubt. But with the advances in UCs come challenges for safety and conservation of marine aquatic ecosystem and also developed and developing countries level playing conflict. The methods of this study were applied international marine policy analysis by under a policy process instrument umbrella. Most of the companies are following the codes, ordinances and master plans for environmental issues and resources, environmentally sensitive site designs, fees, overview, site inspection and construction building. They have some business policy as like as marine insurance and low cost. The policy evaluation shows that the most of the UCs companies try to follow the national or international rules and regulations e.g. construction windows, excavation and disposal policy and permit requirements. Though UC's are necessary for modern society but more than a few underwater constructions including nuclear and power transmission have a long term loss for ocean biodiversity. On the other hand, the policy debate is rising from developing countries that the advanced technologies are mostly used in developed country. Developing countries ocean exploration depends on developed counties technology and experts, and developing countries feel geopolitical insecurity to monitor or constructions using these technologies. Developing countries are not interested to bear the responsibility of marine pollution from the UCs by developed countries. These - - agendas are the most challenging for ocean regime creation problems in 21st century.
In this paper, a device with 3-dimensional microfluidic structure composed of two stacked layers of PDMS (polydimethylsiloxane) is fabricated for mammalian cell culture. This microdevice is tested with Hepatocarcinoma liver cells (Hep G2 cells). The purpose of this study is to understand to what extent cell culture in a PDMS microdevice is available. The experimental protocols for Hep G2 cell culture in the microdevice, such as sterilization steps, collagen pre-coating, etc. have been investigated and established. The oxygen supply could be achieved thanks to the high gas permeability of the PDMS material without any external oxygen supplying system. The cells could be kept in good condition for several days with the present set-up as far as the culture medium is periodically changed. Morphological observations of the cells have shown that they could successfully attach, spread and grow until they reached the confluence over the microfluidic structure. By measuring the glucose consumption and albumin production, the activity of the cells was monitored, and those values had increased gradually along the term of the culture. Those encouraging results illustrate the good cell response to the microfluidic structure, in other words, the culture environment made of PDMS material. In future work, this culture system will be extended to non-cancerous liver cells like normal hepatocytes or endothelial cells.
In this paper, the fabrication and characterization of PDMS 2D-optical lenses are reported. These lenses are designed in order to improve the performance of fluorescent spectroscopy detection performed on a portable chip using optical fibers. The fabrication process of the PDMS layer is first detailed, and the patterns are then checked with a SEM. By comparing various interfacial structures, it is shown that the beam properties of the light coming out from the fiber can be modified depending on the lens curvature radius. As a consequence, for a constant dye concentration, the use of such lenses can increase the intensity of fluorescent response close to the fiber or far from the fiber, compared to the same design with a flat interface. This excitation improvement corresponding to a stronger response from the dye then consequently leads to around three times higher sensitivity of the on-chip detection method for fluorescent spectroscopy.
This study presents a microfabricated device for polymerase chain reaction (PCR) with a flow-through manner for use in environmental microbiology. The device was developed utilizing photolithography and softlithography techniques and evaluated as one component of a totally integrated in situ gene analysis system. The developed device was composed of a glass-based “temperature control chip” and polydimethylsiloxane (PDMS)-based “microchannel chip”. For the temperature control chip, six heaters made from indium tin oxide (ITO) are placed on a glass substrate to define three uniform temperature zones for flow-through PCR. On the each heater, a platinum (Pt) line was placed as a temperature sensor. The PDMS microchannel structure was fabricated by using a molding method with a negatively patterned mold master. The width and depth of folded microchannel was 100 μm and total length for 30 cycles of flow-through PCR was approximately 3.0 m. With the flow-through PCR device, 580 and 1450 bp (base pairs) of DNA fragments were successfully amplified from Escherichia coli genomic DNA and directly from untreated cells.
This paper presents the first in situ flow-through chemical analyzer using a chemiluminescence (CL) method in the deep sea to a depth of 5200 m. The analyzer, called GAMOS (Geochemical Anomalies MOnitoring System), determines the concentration of dissolved manganese continuously using a H2O2–luminol CL method. A detection limit of 0.23 nM was obtained. The GAMOS was used successfully for hydrothermal plume observation.
A microreactor array was developed which enables high-throughput cell-free protein synthesis. The microreactor array is composed of a temperature control chip and a reaction chamber chip. The temperature control chip is a glass-made chip on which temperature control devices, heaters and temperature sensors, are fabricated with an ITO (indium tin oxide) resistive material. The reaction chamber chip is fabricated by micromolding of PDMS (polydimethylsiloxane), and is designed to have an array of reaction chambers and flow channels for liquid introduction. The microreactor array is assembled by placing the reaction chamber chip on the temperature control chip. The small thermal mass of the reaction chamber resulted in a short thermal time constant of 170 ms for heating and 3 s for cooling. The performance of the microreactor array was examined through the experiments of cell-free protein synthesis. By measuring the fluorescence emission from the products, it was confirmed that GFP (Green Fluorescent Protein) and BFP (Blue Fluorescent Protein) were successfully synthesized using Escherichia coli extract.