Authors: J.J. Ahn, J. Oh and B. Choi
Affilation: Sogang University, Korea
Pages: 226 - 229
Keywords: ferrofluid, pipette, microfluidics, microchannel, Lab on a chip
This study was performed to design the novel type of ferrofluid magnetic pipette on a micro scale for the purpose of applications to delivery systems, which is the core device of Lab on a chip in medicine and biology. There were a few previous works on the pipette that is able to precisely control the small quantity of reagents such as one using a piezoelectric tranducer or ferrofluid actuated by electromagnets in place of a device consisting of a plunger in a bore operated by a mechanical linear actuator. The proposed magnetic pipette in this paper has been designed for precise, accurate and fast pipetting in submicronliter range. The magnetic dipole in ferrofluids line up with the applied field due to the permanent magnet with surface gauss 3400. The schematic of a novel type of a ferrofluid magnetic pipette is shown in Fig. 1. The width of microchannels in a device ranges from 100 to 1000um and the depth of these is 100um. The device was fabricated by MEMS technology with Silicon wafer. Magnetically actuated ferrofluid lump moves toward the area the magnetic field is concentrated and acts as a plunger like a conventional mechanical actuated pipette as the permanent magnet makes circular movements on the pyrex glass by the stepping motor. Then in turn these actuations can sample reagents or biological fluids (Fig. 2) The stepping motor with 20 steps was used. One step makes the permanent magnet move 18o in the circumferential direction and sample the liquid in nanoliter level. As compared with the previous ferrofluid magnetic pipette, this device has no heat generation so that there is no harmfulness of biological liquid and no denaturalization of reagents and the response time is so fast because the permanent magnet is used. Of all things, it is a significant point that the possibility that a pipette for sampling the liquid can be integrated in lab on a chip is presented.