Undaria pinnatifida, commonly known as wakame in Japan, is one species of brown seaweeds containing valuable bioactive organic compounds such as fucoxanthin, a carotenoid, which has numerous functional properties. However, most of the seaweeds that do not meet strict quality standards are normally discarded as wastes or returned to the sea, a situation which is becoming an environmental concern. In this research, supercritical carbon dioxide (SCCO₂) extraction was investigated for the isolation of fucoxanthin. SCCO₂ extraction experiments were carried out at temperature range of 25-60 °C and pressure range of 20-40 MPa, at a carbon dioxide flow rate of 1.0-4.0 mL/min. Results showed that fucoxanthin recovery closed to 80% could be obtained at 40 °C and 40 MPa in extraction time of 180 min. The recovery increased with decreasing temperature and increasing pressure. Pretreatment with microwave (MW) also enhanced the efficiency of extraction due most likely to disruption of the cell membrane. Application of SCCO₂, generally regarded as safe and environmentally benign solvent, for extraction of useful bioactive compounds from unwanted or substandard seaweeds look promising in the near future. The extracts obtained using the method can be utilized as food and pharmaceutical additive, and can be used in the development of new health supplements.

Marine algae, such as Undaria pinnatifida, commonly known as “wakame” in Japan, contain valuable bioactive organic compounds including lipids and polysaccharides. However, substandard seaweeds that do not meet strict quality standards are normally discarded as wastes or returned to the sea, a situation which is becoming a serious environmental concern. In this work, hydrothermal treatment of the supercritical carbon dioxide deoiled wakame was investigated using microwave and conventional heating to recover and degrade Undaria polysaccharides (i.e., fucoidan) into highly potent low-molecular-weight components of about 5–30 kDa. Results showed advantages of microwave heating compared to conventional heating, obtaining the target molecular weight at a temperature close to 140 °C. Continuous microwave irradiation at constant microwave power in a short irradiation time of 1 min also gave promising results.

Moving-mask lithography with backside exposure was utilized to generate master male mold for biodegradable polymer microneedle production. The microneedle shape was calculated from the exposure dose, mask geometry, and moving trajectory using a newly developed computer simulation. Two conditions (90 µm aperture with 80 µm diameter of circular movement, and 90 µm aperture with 90 µm diameter of circular movement) were selected to evaluate the moving-mask exposure effectiveness. By changing the moving trajectory, two different sizes of microneedles were obtained from a single-size aperture mask. The fabricated microneedle and calculated microneedle geometry showed good qualitative agreement. The geometrical difference was 2% in basal diameter and 8%-16% in height. Using the master male mold, biodegradable polymer microneedles made of chondroitin sulfate C sodium salt (CSC) were fabricated by casting from a poly-dimethylsiloxane female mold. The shape of the biodegradable CSC microneedles showed good agreement with the master male mold.

Backside lithography with a moving mask UV exposure technique is proposed. A novel moving-mask exposure apparatus was developed and evaluated both experimentally and through exposure simulations. The backside exposure using this technique was validated and is capable of producing tapered microstructures of thick photoresist for molding. The shape of the structure can be modified by the trajectory of the stage movement. It was confirmed that the shape of the processed structure could be successfully predicted using the proposed simulation method.

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