1. Field of the Invention
The present invention relates generally to micro channel array structures. More particularly, the present invention relates to a device constructed by drawing a bulk preform to produce the micro channel array and a method of analysis utilizing such structures.
2. Background of the Invention
As the demand for rapid, accurate and inexpensive analytical techniques has grown, there has been a drive to develop smaller analytical devices. Such small devices can provide the ability to run hundreds or thousands of simultaneous experiments in a single laboratory, allowing heretofore impossible or impractical results to be achieved. For example, combinatorial chemists may now perform thousands of simultaneous syntheses using a fraction of the time and materials necessary to perform even one conventional synthesis. Pharmaceutical researchers, DNA analysts and a wide variety of other biologists and chemists have benefited from the revolution in lab on a chip technologies.
In order to make this possible, lab on a chip devices generally consist of microfluidic systems fabricated on a planar substrate. The substrate is generally selected according to the desired use and may be chosen to be resistant to acids, bases, salts, temperature extremes, temperature variations and/or applied electromagnetic fields. Further, the substrate should be relatively non-reactive with whatever chemicals might be used as part of the experiments to be performed. Examples of such substrates include glass, fused silica, quartz crystals, silicon, diamond and a variety of polymers. The substrate may be opaque or transparent, according to the application. For example, if optical detection is used to monitor the process, transparent substrates may be desirable to allow signal transmission.
In many cases, the lab on a chip may essentially consist of several channels in a surface or in the interior of the substrate. A typical channel may have a depth of about 10 μm and a width of about 60 μm.
Conventionally, lab on a chip devices have been manufactured using techniques similar to those used to fabricate microprocessors and other small scale electronic devices. For example it is common to use photolithography, chemical etching, plasma deposition, ion beam deposition, sputtering, chemical vapor deposition and other techniques commonly used in the semiconductor industry. Such techniques tend to be expensive and capital intensive. A single photolithography system can cost up to $20 million, not including the associated facilities such as clean rooms, vibration isolation structures and the like.
Moreover, photolithography has been unable to successfully produce channels with high aspect ratios or straight walls, has an inherently low production rate and generally uses materials which are of lower quality such as borosilicate glass or plastics.
In lieu of the above fabrication methods, micromachining techniques such as laser drilling, micro milling and the like or injection molding, microcasting or other casting techniques may be used. These techniques are generally slow and involve extremely high precision machining operations at the limit of current technologies.
In the manufacture of optical fibers, a pure silica tube has a doped silica layer deposited onto its interior surface by a process known as chemical vapor deposition. The tube is heated to cause it to collapse into a solid rod. The rod is heated and drawn to greatly increase its length and reduce its cross section, creating a flexible optical fiber.
For certain applications, a glass rod may be formed with pores therein prior to drawing to serve as a pipette, for example. The drawn fiber has tubes formed by the stretched pores. The tubes extend along the length of the fiber.