Comprendre la Microfluidique

Understanding Microfluidics

Microfluidics is the science of manipulating fluids at the micron scale. This research is now booming and is inspired by nature, which has perfectly already mastered these techniques.

The plant kingdom

 

 

The tree distributes the sap in millions of micrometric capillaries under very tight control.

 



The animal kingdom

The spider runs a very sophisticated microreactor to produce the material for his web.
In the cell, matter exchanges through the membrane are strictly controlled.

 

 

 

Microfluidics is a young topic. It has actually emerged as a discipline in the 2000s. It is characterized by an impressive growth in innovation and in the number of publications.
These developments are related to a strong demand in the fields of life science, medicine, chemistry and environment. Microfluidics can be seen both as a science (the study of the behavior of fluids in microchannels) and a designing technology for lab-on-chips devices in physics, chemistry and biology.


Industrial applications

For a decade, manhood imitated nature in producing objects with micrometric flows.
The applications are numerous. Usually, manipulating at the micron scale allows working faster, cheaper, in a cleaner and safer environment.
Microfluidic systems are devices that include a set of miniaturized components allowing the study and analysis of chemical or biological samples. Those "microprocessors for biology" can replace bulky and expensive instruments. Microfluidics is definitely a revolution for biology and chemistry, similar to what microprocessors brought to electronics and computer science.
Today, the volume of activity of microfluidic technologies is estimated at ten billion euros.
The number of industrial applications is considerable: in medicine, energy, green chemistry, cosmetics, food industry, etc.

Some examples

1. Inkjet printer head
2. Micropumps
3. Heart attack lab-on-chip diagnosis device
4. Genotyping microarray
5. Electronic paper
6. Touchscreen technology with relief
7. Urine pregnancy test
8. Blood test for HIV screening

1. The ink- jet printer head, appeared in the 1990, is made of an ink tank, a heater to set in motion the fluid, and a nozzle. Today, tens of millions of ink jet printers use microfluidic technology and billions of documents are written and read using it.


The sprinkler cannot control the generated drops, while the small print head does it very well.

 

 

2. Micropumps allow injecting a product into the human body. This mode of injection is way more efficient than the oral way. The insulin pump in the liver for the treatment of diabetes also has considerable gain in comfort for the patient.

3. The lab-on-a-chip system that, from a patient drop of blood, allow diagnosing an upcoming heart attack. The results of the analysis are given after processing on a computer. The diagnosis is delivered in 15 minutes, whereas traditional systems require about ten hours.

4. The chip for genotyping allows identifying an object (for example virus) from its specific gene sequences but also RNA and protein identification.

5. Electronic paper is an electronic display technology on flexible substrates that mimics the appearance of a printed sheet and, just like paper, does not require energy to leave a text ora picture displayed.

6. The touch screen in relief makes real physical keys appear and retract on demand, leaving behind a perfectly smooth and flat surface. Commercialization is planned for mid-2013.

7. Much more widespread around us, the pregnancy test using a urine sample to determine with precision (estimated at 99% reliability) a possible pregnancy. Easy to use, this miniaturized system analysis the sample in less than one minute and provides a simple reading of the result.

8. The blood test on a chip can now detect the AIDS virus, syphilis and a dozen other infectious diseases (hepatitis B and C, herpes, etc.) simultaneously. With a single drop of blood, the results are read through an optical sensor or even the naked eye in only twenty minutes.

The technologies developed will allow:

  • In biology, processing a large number of samples, conducting experiments on the scale of the cell and understanding the interactions between cells, improving the accuracy and timeliness of diagnosis as HIV, reducing experimental volumes...
  • In chemistry, testing thousands of reactions, encapsulating chemical reactions in microfluidic drops...
  • In physics, creating controlled automated systems and experimental set-ups…

Today, a large number of companies are developing microfluidic technology. More than 250 companies and 250 research teams are working on it around the world.

 

Great names in microfluidics

George M. WHITESIDES

Born in 1939 in the USA, is now a professor at Harvard University. His work led to major contributions in very diverse areas such as Nuclear Magnetic Resonance spectroscopy, organometallic chemistry and biocatalyzed organic synthesis. His works in microfluidics, materials science, surface chemistry and nanotechnology have a strong impact, not only in chemistry but also in biology and bioengineering. 

Takehiko KITAMORI

Professor Kitamori is vice president of the University of Tokyo, responsible for human resources development and internationalization. He is also Professor in the Department of Applied Chemistry.His research interests are chemical systems integration on microchips, laser spectroscopy for ultrasensitive detection, analytical chemistry and microfluidics at the submicron scale.

Andreas MANZ

Andreas Manz (born December 12, 1956) is a Swiss researcher in analytical chemistry, former director of the Leibniz-Institut für Analytische Wissenschaften (ISAS) and professor at the University of Dortmund. His research activities deal with lab-on-a-chip for chemical analysis and micro total analysis systems.

Physical concepts of Microfluidics

Physicists have characterized the properties that govern microfluidics:

Laminarity

The small size of the channels removes the unavoidable flow instabilities usually found in "ordinary" sized systems.

Capillarity

In the "small world", flow behavior is driven by capillary forces.

Wettability

The behavior of fluids on a surface depends greatly on its hydrophilic or hydrophobic character.

Heat conduction

Microfluidic systems are really efficient to remove heat. The homogenization of the temperature is also very well done.
Large animals such as whales have no trouble keeping their body temperature without having to continuously feed to provide energy.
The very small animals, like the pygmy shrew, must eat constantly to compensate for heat loss and keep their temperature around 35°C.

Electrokinetic effects

As the electric field generated by applying a voltage is inversely proportional to the distance between electrodes, it greatly increases when the distance decreases.

Using these five key concepts, you can create any imaginable microfluidic systems and thus lead to a large range of applications that are used for research in diverse fields (chemistry, health, energy production…), in products currently sold or about to be.