Various studies have been carried out on biological, electromechanical micro devices such as a lab-on-a-chip device for the purposes of miniaturization, cost reduction, integration, automation, and real time diagnosis. Particularly, many studies are recently carried out on biochips or biosensors for biochemical analysis. Since many expensive reaction samples are used in such biochips or biosensors for detecting specific biomaterials from bio samples or analyzing specific biomaterials, there is an increasing need for a reliable and inexpensive micro fluidic transportation device that can be used for detecting and analyzing a specific biomaterial using a small amount of a reaction sample without influences by environmental pollutants.
Various methods have been proposed for efficient transportation of micro amounts of fluid. Examples of such methods include: mechanical pumping; thermal pumping using thermal expansion; micro-actuator pumping; electrochemical pumping such as electrophoretic pumping for transporting micro amounts of fluid using a voltage applied to a micro channel, and electro-osmotic pumping; and capillary flow pumping using paraffin and a capillary jack valve.
In micro fluidic transportation devices using such pumping methods, only a portion of an expensive reaction sample reacts with a biological sample since the samples flow during the reaction. Furthermore, an additional device is necessary to disperse proteins or DNAs included in the biological sample or maintain the proteins or DNAs at a dispersed state.
To address these problems, a micro fluidic transportation device has been disclosed in Lab on a chip, 2005, vol 5, pp. 308-317 by the Advalytix company, Germany. The disclosed micro fluidic transportation device uses a piezoelectric substrate formed of a piezoelectric material (LiNbO3) and surface acoustic wave (SAW) to control transportation of nano litters of fluid.
However, the micro fluidic transportation device proposed by Advalytix is expensive and is not suitable for use in disposable biochips or biosensors since the proposed micro fluidic transportation device uses a piezoelectric substrate that is expensive compared with silicon, glass, and plastic substrates. Furthermore, it is difficult to process the piezoelectric substrate with existing semiconductor manufacturing equipment designed based on silicon substrates.
Therefore, there is a need for an inexpensive micro fluidic transportation device for controlling transportation of micro amounts of fluid in a lab-on-a-chip type device such as a disposable biochip or biosensor for biochemical analysis.