A review on Microfluidic systems for detection of pathogens

Being associated with molecular diagnostics of infectious agents for past so many years, I can easily identify with the need to develop faster, portable and more accurate methods for diagnosis of pathogenic microorganisms. For the last few years, much advancement has been made in this regard. This blog is on a very interesting review article from the laboratory of Dr. Peter Ertl, Viena, Austria on microfluidic systems for pathogen sensing.

Microfuidics is explained in Wikipedia as one that deals with the behavior, precise control, and manipulation of fluids that are geometrically constrained to a small typically sub-millimeter scale. It is a multidisciplinary field intersecting engineering, physics, chemistry, biotechnology, and microtechnology. It involves design of systems in which small volumes of fluid are used. It is used in the development of inkjet printheads, lab-on-a-chip technology, micro-propulsion and miceo-thermal technology.

The standard methods which are used for pathogen detection include pathogen culture, enzyme immuno assays and polymerase chain reaction. All these methods take 2-4 days and generally require to be performed in centralized labs. As most centralized labs are limited to larger cities, there is a need to develop near patient testing which is commonly referred to as point of care (POC) testing. Therefore robust and portable diagnostic devices capable of rapidly providing information on pathogens will also help reduce mortality rates and hospitalization in case of infectious pathogens. In the last two decades a variety of different biosensors have been developed. Still, miniaturized, low cost or disposable biosensors capable of rapid detection and accurate identification of a wide range of pathogens are required. Thus, efforts have been made to minimize the time span between sampling and results. The results of these efforts are miniature devices that do not depend upon special infrastructure and sample preparation procedures. The area of miniaturized or microfluidic analysis systems, which are also called "micro total analysis system" or "lab-on-a-chip (LOC) system".

The major advantages of the microfluidic systems are:

• To conduct measurements from small volumes of complex fluids with efficiency and speed.
  
• No need for a skilled operator
  
• Reduced consumption of reagents due to small size
  
• Ability to integrate separation and monitoring techniques within a single device.
  
• Portable LOC devices are able to provide information in even in most remote settings.
  

In this review the recent progress within microfluidic based pathogen detection is presented. A schematic overview of microfluidic based pathogen sensing is presented in this flow chart.

Source: Mairhofer J, Roppert K, Ertl P. Microfluidic systems for pathogen sensing: A Review. Sensors 2009, 9, 4804-4823.