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A lab-on-a-chip ( LOC) is a device that integrates one or several laboratory functions on a single integrated circuit (commonly called a "chip") of only millimeters to a few square centimeters to achieve automation and high-throughput screening. LOCs can handle extremely small fluid volumes down to less than . Lab-on-a-chip devices are a subset of microelectromechanical systems (MEMS) devices and sometimes called "micro total analysis systems" (μTAS). LOCs may use microfluidics, the physics, manipulation and study of minute amounts of fluids. However, strictly regarded "lab-on-a-chip" indicates generally the scaling of single or multiple lab processes down to chip-format, whereas "μTAS" is dedicated to the integration of the total sequence of lab processes to perform chemical analysis.
Next to pressure sensors, airbag sensors and other mechanically movable structures, fluid handling devices were developed. Examples are: channels (capillary connections), mixers, valves, pumps and dosing devices. The first LOC analysis system was a gas chromatograph, developed in 1979 by S.C. Terry at Stanford University. However, only at the end of the 1980s and beginning of the 1990s did the LOC research start to seriously grow as a few research groups in Europe developed micropumps, flowsensors and the concepts for integrated fluid treatments for analysis systems.A.Manz, N.Graber and H.M.Widmer: Miniaturized total Chemical Analysis systems: A Novel Concept for Chemical Sensing, Sensors and Actuators, B 1 (1990) 244–248. These μTAS concepts demonstrated that integration of pre-treatment steps, usually done at lab-scale, could extend the simple sensor functionality towards a complete laboratory analysis, including additional cleaning and separation steps.
A big boost in research and commercial interest came in the mid-1990s, when μTAS technologies turned out to provide interesting tooling for genomics applications, like capillary electrophoresis and DNA microarrays. A big boost in research support also came from the military, especially from DARPA (Defense Advanced Research Projects Agency), for their interest in portable systems to aid in the detection of biological and chemical warfare agents. The added value was not only limited to integration of lab processes for analysis but also the characteristic possibilities of individual components and the application to other, non-analysis, lab processes. Hence the term "lab-on-a-chip" was introduced.
Although the application of LOCs is still novel and modest, a growing interest of companies and applied research groups is observed in different fields such as chemical analysis, environmental monitoring, medical diagnostics and cellomics, but also in synthetic chemistry such as rapid screening and microreactors for pharmaceutics. Besides further application developments, research in LOC systems is expected to extend towards downscaling of fluid handling structures as well, by using nanotechnology. Sub-micrometre and nano-sized channels, DNA labyrinths, single cell detection and analysis, and nano-sensors, might become feasible, allowing new ways of interaction with biological species and large molecules. Many books have been written that cover various aspects of these devices, including the fluid transport, system properties, sensing techniques, and bioanalytical applications.
The size of the global lab on chip market was estimated at US$5,698 million in 2021 and is projected to increase to US$14,772 million by 2030, at a CAGR of 11.5% from 2022 to 2030
The development of LOC devices using printed circuit board (PCB) substrates is an interesting alternative due to these differentiating characteristics: commercially available substrates with integrated electronics, sensors and actuators; disposable devices at low cost, and very high potential of commercialization. These devices are known as Lab-on-PCBs (LOPCBs). The following are some of the advantages of PCB technology: a) PCB-based circuit design offers great flexibility and can be tailored to specific demands. b) PCB technology enables the integration of electronic and sensing modules on the same platform, reducing device size while maintaining accuracy of detection. c) The standardized and established PCB manufacturing process allows for cost-effective large-scale production of PCB-based detection devices. d) The growth of flexible PCB technology has driven the development of wearable detection devices. As a result, over the past decade, there have been numerous reports on the application of Lab-on-PCB to various biomedical fields, including the fastest SARS-CoV-2 molecular diagnostic test. e) PCBs are compatible with wet deposition methods, to allow for the fabrication of sensors using novel nanomaterials (e.g. graphene).
Another active area of LOC research involves ways to diagnose and manage common infectious diseases caused by bacteria, e.g. bacteriuria, or , e.g. influenza. A gold standard for diagnosing bacteriuria (urinary tract infections) is microbial culture. A recent study based on lab-on-a-chip technology, Digital Dipstick, miniaturised microbiological culture into a dipstick format and enabled it to be used at the point-of-care. Lab-on-a-chip technology can also be useful for the diagnosis and management of viral infections. In 2023, researchers developed a working prototype of an RT-LAMP lab-on-a-chip system called LoCKAmp, which provided results for SARS-CoV-2 tests within three minutes. Managing HIV infections is another area where lab-on-a-chips may be useful. Around 36.9 million people are infected with HIV in the world today, and 59% of these people receive anti-retroviral treatment. Only 75% of people living with HIV knew their status. Measuring the number of CD4+ T lymphocytes in a person's blood is an accurate way to determine if a person has HIV and to track the progress of an HIV infection. At the moment, flow cytometry is the gold standard for obtaining CD4 counts, but flow cytometry is a complicated technique that is not available in most developing areas because it requires trained technicians and expensive equipment. Recently such a cytometer was developed for just $5. Another active area of LOC research is for controlled separation and mixing. In such devices it is possible to quickly diagnose and potentially treat diseases. As mentioned above, a big motivation for development of these is that they can potentially be manufactured at very low cost. One more area of research that is being looked into with regards to LOC is with home security. Automated monitoring of volatile organic compounds (VOCs) is a desired functionality for LOC. If this application becomes reliable, these micro-devices could be installed on a global scale and notify homeowners of potentially dangerous compounds.
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