K. Ikuta, T. Adachi, Nagoya University, Nagoya, Japan; T. Hasegawa, Osaka Institute of Technology, Osaka, Japan
The authors have been conducting a versatile micro fluidic device named “Biochemical IC Family” for these years. The biochemical IC chip contains different functional devices such as multiple connectors, pumps, valves, reactors, concentrators. The total micro chemical system can be constructed by stacking various kinds of chips. Recently, though a large number of studies have been made on miniaturization of chemical components such as reactors in the fields of μ-TAS, these micro devices demand external apparatus such as pumps, sensors for practical use. Accordingly, the total experimental setup with these micro devices becomes larger. On the other hand, the aim of our research is to miniaturize a total micro chemical system, which integrates micro fluidic parts and electronic parts. Our approach is useful for “portable” micro chemical devices. Therefore, the biochemical IC demands the micro fluidic chip, which can supply the micro fluidics stably.
The micro pump chip actuating by SMA have been already fabricated. Each pump has reciprocating pumps, consisting of two check valves made of silicone rubber, a deformable chamber, a spacer and a SMA actuator. The actuator cycles the volume of the deformable chamber, while the check valves ensure unidirectional flow through the chamber. Its basic performances in the modular micro device system were demonstrated. At the next stage, the micro pump should be improved to achieve high performance with stable driving for practical applications.
In this paper, we present the optimization of the pump design by improving design to satisfy insensitive ability to gas bubbles and self-priming. Because of the pumping principle, three elements of the micro pump were optimized as follows:
1) Pressure loss of the check valves
2) Flow pattern inside the chamber
3) Compressibility of the deformable chamber
As a result, these improvements enable us to flow gases as well as liquids.
Summary: We fabricated a high performance SMA micro pump chip. This chip can flow not only liquids but also gases (12
ml/min., 25 kPa for water. 11
ml/min., 5 kPa for air ). Moreover, the micro pump is tolerant of gas bubbles in the liquid chamber and it is possible to prime itself. To achieve this performance, the micro pump improved three elements: pressure loss of the check valves, flow pattern and compressibility of the deformable chamber. The micro pump chip was fabricated using our original method of hybrid micro stereo lithography (hybrid-IH process), thereby eliminating the need for micro assembly and bonding.
