This application claims the benefit of the filing date of Provisional Patent Application No. 60/382,854, filed on May 23, 2002.
Microfluidics is the flow of fluids in very small channels having a size in the range of 1–500 microns. The flow of fluids in such microfluidic systems is significantly different than that of larger systems due to the large surface to volume ratios in Microsystems. The properties of the flow surface such as hydrophobicity, hydrophylicity, ion conductivity, roughness and adsorbtivity may play a significant role in microfluidic systems. In some cases, the fluid flow and its control is dependent on such properties.
Microfluidic systems may comprise a number of functional elements or components configured to pump the flow, mix components, heat materials, initiate chemical reactions, control and monitor a variety of fluid processes in such systems. The components may include a network of channels and reservoirs, micropumps, valves, microheaters, reaction and mixing chambers, connectors, measurement ports and sensors (either internal or external), and often imbedded electronics to control, monitor and measure the various phenomena that occur in the system.
The last decade has seen a significant amount of development in microfluidics technology aimed at the miniaturization of the currently used methods in the pharmaceutical industry for drug design and synthesis, DNA and proteomic research, as well as development of instrumentation for testing biosamples such as blood, urine, etc. Other applications include fluid handling for micro-power generators (fuel cells and microturbines), miniature liquid and gas chromatography.
A typical conventional microfluidic system comprises a plate or chip with a single flow structural configuration which may comprise 1) a network of microchannels and chambers, 2) micropumps, 3) microvalves, 4) fluidic connectors, 5) measurement and observation ports, 6) microheaters or gas injection mechanisms, 7) electrical contact point to induce electro-osmotic and electro-phoretic flows, 8) instrumentation for microflow measurement, 9) observation equipment such as a microcamera or microscope and 10) a computer to control the experiments and to record and display the systems data.
The network of microchannels and chambers may be in the range of 5–500 microns wide and 2–250 microns deep. These may be fabricated using any of the various known micromachining techniques such as bulk micromachining, surface micromaching, etching, electrodischarge machining, stamping, imprinting, micromilling and lithography. The microchannels may be fabricated from a variety of materials such as silicon, silicon dioxide, plastics, glass and metals. A variety of micropumps can be used in the present system. Examples are conventional piezo-pumps, diaphragm pumps, bubble pumps and electrokinetic pumps. These pumps are able to handle very small quantities of liquids in the range of nano- to microliters. Microvalves are necessary components used to switch on and off the flow in the channels as well as to control the flow rates. Examples of conventional microvalves include electostatic valves, diaphragm valves, MEMS-based mechanical slides, and bubble-based valves. Fluidic connectors are required to either interconnect the various elements of a microfluidic system or the microfluidic system to external sources of fluid, pressure sources, etc. These connections can be permanent or temporary in nature. Measurement and observation ports are designed in the microfluidic system for obtaining data and observing the fluid properties, respectively. These ports are either optically or electronically accessible which measure optical, physical or chemical properties in the system. Microheaters or other gas injection mechanisms which produce vapor or gas bubbles in the channel are usual components of a microfluidic system. Microheaters are made of silicon or thin film deposition of metals such as platinum or tantalum in the form of coils. The size of the heaters may be from 50 microns to 500 microns. Electrical contact points to induce electro-osmotic and electro-phoretic flows are provided in the reservoirs of the device. When an electrically conducting liquid is filled in the reservoirs and a DC voltage is applied between the two reservoirs, a flow is generated between the reservoirs due to the mobility of the ions that are generated in the fluid. Conventional microflow measurement instrumentation is available to measure flow properties such as pressure, flow rate and temperature. Specific instruments are readily available and may be employed to measure one or more of these flow properties. Other properties that are measured are the light intensity generated by chemi-luminescence or fluorescence in the fluid and electrical currents and resistances generated by specific molecules in the fluid. Conventional microfluidic systems may employ a microscope or camera equipment for observation of the fluid flow, a computer to display the microfluidic flow, control the experiments and record the data are also used in practice.
The rapid development of the microfluidics technology has created a large demand for personnel trained to operate the large variety microfluidics systems currently being developed and in actual use. While there are a variety of educational and training systems available in the market for other technical areas such as mechatronics apparatus (U.S. Pat. No. 5,562,454), mathematical apparatus (U.S. Pat. No. 6,196,847), fluid dynamics simulator (U.S. Pat. No. 5,609,405), to the best of the inventor's knowledge, there is no single training system or apparatus for microfluidics training available in the market. The microfluidic systems currently being developed by industries—referred in literature as “lab-on-a-chip”, “bio-chip” and “assay-chip” are specifically geared towards particular testing methods. These prior art microfluidic systems are not capable of providing a more comprehensive/multicomponent microfluidic system that can provide a generalized and systematic training program for the student or learner. The prior art microfluidic systems are typically designed for specific or single functionality and accomplish specific tasks or analyses, whereas the educational microfluidic system of the present invention is generically designed to serve as a microfluidic system teaching apparatus containing multiple flow structural configurations fabricated on a single plate capable of providing student training in a multiplicity of tasks and analyses at varying levels of educational difficulty. Therefore, one major object of the present invention is to provide a multicomponent or multiple flow structural configuration microfluidic systems on a single plate that may be used for educating and training scientific personnel in the use of both basic and advanced microfluidics technology systems.