This paper shows the novel type of microfluidic system for the purpose of applications to delivery systems, which is the core device of l-TAS (micro Total Analysis System) in medicine and biology. The proposed microfluidic control device in this work has been designed for precisely actuating and fast sampling in submicroliter range. Also, the biological liquids have not been contaminated since they have been isolated from the ferrofluids. The magnetic dipoles in ferrofluids line up with the applied field due to the permanent magnet with surface gauss 3400. The maximum net pressure by ferrofluid flows in the rounded microchannel was more than 2 kPa. The device was fabricated by MEMS technology with silicon wafer. The stepping motor with 20 steps was used for the control of delivering the liquids. One step makes the permanent magnet move 18°in the circumferential direction and the liquids can be sampled in nanoliter level. This study presents a significant point that a microfluidic delivery system for sampling biological liquids with high pressure in a microchannels can be integrated in l-TAS.

Experiments were performed to investigate the characteristics of magnetic fluids on a micro scale for the purpose of applications to a micro pump, which is the core device of Lab on a chip in medicine and biology. This work took an advantage of the phenomenon that the viscosity of a magnetic fluid decreases sharply as the temperature increases gradually. The magnetic fluid flowing through a trapezoidal silicon microchannel was heated below the temperature at which the magnetism in the magnetic fluid is not lost. As the temperature increases, the magnetic fluid became less viscid. This in turn made the pressure drop in the microchannel. Thus, this pressure drop of the heated magnetic fluid and the corresponding temperature were measured. The microchannel was fabricated by MEMS technology. Since the sheet resistance is as high as 10.6@, platinum was selected as the material of the folded film heater with the length and the thickness of 7.26 cm and 1000 Aon Pyrex glass, respectively.At a proper temperature, if a magnetic fluid is applied to the magnetic field and its viscosity decreases, the response time and the net unidirectional flow of actuators such as a micrc .;.;mp are expected to be improved