Pumps – One fluid pumped by contact or entrainment with another – Jet
Reexamination Certificate
2002-05-29
2004-01-27
Yu, Justine R. (Department: 3746)
Pumps
One fluid pumped by contact or entrainment with another
Jet
C417S163000, C417S165000
Reexamination Certificate
active
06682311
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a driving device for micro fluids and especially relates to a pneumatic driving device and the associated method for micro fluids. By the concept of recursion, a recursive pneumatic driving device and its associated method for micro fluids can be established.
2. Related Art
Because of the recent development of biochips the related technologies in the field are becoming more important ever than before, and the micro-scale total analysis system (&mgr; TAS) for biochips has become the necessary key point to the design and analysis of biochips. Hence, the associated so-called micro fluid systems for biochips have become a serious research subject and are being studied extensively. The micro fluid systems let the biochips completely function and can allow the bio-chemical substances inside the biochips mix and react with the examined species entering into the biochips completely. They comprise many micro fluid elements such as micro pumps, micro valves, micro fluid pipes and micro fluid mixers. In order to integrate these micro fluid elements to become a complete micro-scale total analysis system, new and innovative structures and manufacturing processes for biochips should be further studied.
Usually the micro fluid system has to separate the incoming micro fluids into several parts, and in the mean time micro valves are conventionally utilized to separate the incoming micro fluids and to guide them into one of the following branch pipes. Micro valves are active parts and have two disadvantages when they are in use, that is, they are more expensive and their performance is not so stable. Therefore, much research has been proposed to attempt to use passive parts in constructing micro valves to overcome these disadvantages. Related research results about the micro fluid systems in the past, for example the studies of micro pumps and micro fluid switchers, are described as follows:
1. On-chip built-in mechanical micro pump: this kind of micro pump can be directly built on biochips by micro-machining technology and with this design some movable parts should be set inside the biochips. Some proposed designs based on this concept are described as follows:
First is the electrostatically driven diaphragm micro pump invented by Roland Zengerle etc., (U.S. Pat. No. 5,529,465), wherein the main body of the micro pump comprises four layers of silicon substrate. Pumping action can be accomplished by the pulsating electrostatic attraction among the upper two silicon layers induced by supplying the specific AC current (50V, 400 Hz) together with two passive check valves. The performed flow rate is about 350 &mgr;l/min.
The micro machined peristaltic pump invented by Frank T. Hartley (U.S. Pat. No. 5,705,018) is a more succinct design. With this design serial flexible conductive strips are placed on the inner walls of the micro pipes of the biochips and when the electric potential pulse waves go through above the micro pipes, the serial flexible conductive strips are attracted by the electrostatic forces to move upward in sequence to form the peristaltic phenomenon of the micro pipes. Accordingly this peristaltic phenomenon can be utilized to drive the micro fluids to flow inside the micro pipes. The phase of the applied electric potential pulse waves must be carefully controlled and the peak value is about 100 V. The performed flow rate is 100 &mgr;l/min.
The disadvantages of the above described on-chip built-in mechanical micro pumps are that the structures are too complicated, it is not easy to clean the micro pumps, and the manufacturing and assembling processes are difficult. These built-in mechanical micro pumps cannot be used repeatedly when they are applied to test the chemical reagents because it is very difficult to completely clean them. So, a biochip is used only one time and then discarded, but this greatly increases production cost. Unfortunately for the on-chip built-in mechanical micro pumps and the on-chip built-in peristaltic pump complicated manufacturing processes and/or costly specific materials must be utilized. Thus the production cost will be greatly increased, and of course, this result is contrary to the requirements of mass production.
In 1998 Andrews S. Dewa and Christophe J. P. Servrain proposed the design concept of remote actuators for micro fabricated fluidic devices (U.S. Pat. No. 5,788,468), wherein the active movable parts (actuators) of micro pumps are replaced on the outside surrounding regions of the biochips. Inside the biochips are placed only the on-chip movable members that are formed by LIGA technology and are similar to pistons or turbines. The actuators placed outside the biochips can drive the on-chip passive movable parts settled inside the biochips to reciprocate or to rotate in specific pump chambers to accomplish the pumping action. The focus of this proposed patent is that different precious on-chip movable parts can be easily established by LIGA technology and can be applied easily together with the associated unsophisticated chambers to achieve the pumping action for micro fluids. Hence this invention has partially overcome the problem of the high production cost of one-time-use biochips. However, the question of how power can be transmitted from the outside actuators to the on-chip movable parts was not answered.
If the outside actuators are connected with the on-chip movable parts by levers, then the movable parts cannot be completely sealed inside the pumping chambers. It is reasonable that the required engineering specifications for the production of biochips must be enhanced so that the micro fluids cannot leak out of the pumping chambers under the reciprocation of the movable parts and under the high pressure inside the pumping chambers. It was suggested in the above-described patent to utilize the magnetic rotor device to drive the movable parts sealed completely inside the pumping chambers to accomplish the pumping action by the electromagnetic effects. This suggestion was also proposed by Kaluji Tojo and Yoshiaki Hirai in 1997 for their invention “micro flow controlling pump” (U.S. Pat. No. 5,599,175). However, specific and expensive materials must be utilized to construct the magnetic pulp bodies as the movable parts.
2. On-chip built-in electrode micro pump: this kind of micro pump is not a mechanical micro pump and with this design it is not necessary to set movable parts inside the micro pump. Conventional operating principles for this kind of micro pump are classified in three different types (electroosmosis EO, electrohydrodynamics EHD and electrophorosis EP) and will be described as follows:
The invention “apparatus and methods for controlling fluid flow in micro channels” (U.S. Pat. No. 5,632,876) proposed by Peter J. Zanzucci etc. in 1997 is a combinative application of electroosmosis and electrohydrodynamics, wherein four electrodes classed among two pairs are interlaced inside the micro pipes of biochips. The inner pair of electrodes is set close to each other and both stretch into the micro fluids inside the micro pipes. The current circuit can be formed by this pair of electrodes and the surrounding micro fluids around this pair of electrodes when a high voltage is supplied. At the same time the surrounding micro fluids around this pair of electrodes is pushed to move along the direction against the current direction. This phenomenon is the so-called Electrohydrodynamic pumping (EHD Pumping). The other outside pair of electrodes is placed a little farther away from each other and only touch the pipe walls of the micro pipes. When hundreds to thousands of high voltages are supplied to the outside pair of electrodes, the pipe walls of the micro pipes are firstly electrically charged, then negative and positive electric charges gather on the material surfaces where the positive and negative electrodes are, respectively, and consequently when the micro fluids contain negative electric particles, these particles are attracted toward the direction to the
Chung Yung-Chiang
Huang Shr-Hau
Kuo Yuan-Fong
Wu Te-Chun
Industrial Technology Research Institute
Sayoc Emmanuel
LandOfFree
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