Scientists dream, as other people do. However, they dream for the welfare and betterment of humanity as a whole. When dream has a deadline, it is called a goal. Lab-on-a-chip has become a future goal for the scientists and researchers.
Lab-on-a-Chip technology is a rapidly extending area of science with applications in biotechnology, clinical diagnostics, chemical analysis, and pharmaceutics.
Looking back at the history, we see that IBM launched the first computer with a hard disk drive (HDD) in 1956. The HDD weighed over 1000 kg and stored only 5MB of data. IBM needed an airplane at that time to transport that HDD storage device. Now we can place several GB data on our fingertip. The race of miniaturization started with the development of transistor and photolithography, and nowadays we have come to an era where scientists and engineers are trying to build a laboratory on a tiny chip.
The term “Lab-on-a-chip (LOC)” feels like an exaggeration, but it is a fact. LOC is a chip of only millimeters to a few square centimeters in size capable of performing several functions that are normally done in laboratory.
Hype was created with the introduction of the term LOC. Expectations started building up. It turned out to be the dream of scientists to fabricate fully functional laboratory on a small piece of substrate that may be a glass, Silicon or any polymer like PDMS. A normal chemical analysis laboratory has several functions to perform that include mixing, separation, identification, and storage of chemicals and interpretation of results. When we go to a blood test laboratory, they take sample of our blood. Then, several functions are performed that make them able to deduce the results. Similarly, LOC also requires mixers, liquid flow channels, separators, storage wells, sensors, etc to complete the whole cycle from sampling to results. LOC is often called a subset of MEMS for good reasons because the components of a normal lab-on-a-chip like wells, mixers, micro pumps and a few others were borrowed from the MEMS technology. At the beginning of the 1990s, the LOC research started to seriously grow when the funding agencies realized the potential benefits hidden in these chips.
-How lab-on-a-chip is fabricated?
The root of the fabrication processes for LOC can be easily tracked down in the well-developed semiconductor fabrication technologies. The invention of photolithography gave a boost to miniaturization of devices back as far as in 80’s. The same photolithography is also being applied in the manufacturing of LOC. However, semiconductor technology is based on the Silicon that is not a material of interest as a substrate for performing biological test.
Attention was paid to Glass, PDMS and ceramics that have the properties desirable for LOC like specific optical characteristics, biocompatibility, and lower production costs. As rightly said that “necessity is the mother of invention”, engineers also developed new methods that were easily implementable with the materials like PDMS, glass etc. These methods include Hot embossing (or imprinting), injection molding, soft lithography etc. Details of these methods are out of the scope of this article. Therefore, summing up all these facts, we can say that fabrication process for LOC is a mixture of old and new techniques.
-Current status and future of LOC.
Currently, LOC is in active research phase. The total market for biochips was $2.4 billion in 2008, which rose to $2.6 billion in 2009. Expected market growth rate for biochips (LOC, DNA chip, Protein chip) in future is almost 17.7% to reach $5.9 billion by 2014, according to BCCresearch. Some prototypes have been demonstrated that are fully functional but manufacturing of LOC have not started yet on commercial basis. There are various challenges with the scaling down of traditional chemical principles. Mixing of two or more streams of fluids in micro size channels, and the signal to noise ratio (SNR) are the two major hurdles faced by the researcher in implementation of the technology to daily life. Nevertheless, the prospects are immense.
Successful implementation of the technology will enable us to have small cell-phone-size devices to carry out medical examinations like blood test, urine analysis and DNA analysis in real time. Nowadays, these tests take from hours to weeks from sampling to results. Even, the technology will enable us to wear laboratory in form of wristwatch to check our body functions and parameters in real time and free of cost.
LOC needs only Pico liters of sample for testing purpose. For the sake of comparison, a drop of water is millions time larger than the liquid required for LOC. Complete mixing of two such a small liquid is the biggest issue in LOC. is possible with the help of LOC. DNA analysis,
LOC may hold the key to the future of the in-vitro analysis. These devices could one day guide us to a pinhead-sized implant or skin-mounted device able to instantly figure out the presence of disease bacteria or biochemical agents, Effective Drug delivery, DNA analysis. Lab-on-a-chip technology may soon become an important part of global health improvements through the development of point of care (PoC) testing devices.