Fluidics

Fluidics (also known as Fluidic logic) is the use of a fluid or compressible medium to perform analog or digital operations similar to those performed with electronics. 

The physical basis of fluidics is pneumatics and hydraulics, based on the theoretical foundation of fluid dynamics. The term Fluidics is normally used when the devices have no moving parts, so ordinary hydraulic components such as hydraulic cylinders and spool valves are not referred to as fluidic devices. The 1960s saw the application of fluidics to sophisticated control systems, with the introduction of the fluidic amplifier. 

A jet of fluid can be deflected by a weaker jet striking it at the side. This provides non-linear amplification, similar to the transistor used in electronic digital logic. It is used mostly in environments where electronic digital logic would be unreliable (e.g., systems exposed to high levels of electromagnetic interference or ionizing radiation).

Nanotechnology considers fluidics as one of its instruments. In this domain, effects such as fluid-solid and fluid-fluid interface forces are often highly significant. Fluidics have also been used for military applications.

Amplifiers :

The basic concept of the fluidic amplifier is shown here. A fluid supply, which may be air, water, or hydraulic fluid, enters at the bottom. Pressure applied to the control ports C₁ or C₂ deflects the stream, so that it exits via either port O₁ or O₂. The stream entering the control ports may be much weaker than the stream being deflected, so the device has gain.

Given this basic device, flip flops and other fluidic logic elements can be constructed. Simple systems of digital logic can thus be built.

Fluidic amplifiers typically have bandwidths in the low kilohertz range, so systems built from them are quite slow compared to electronic devices.

Systems :

Fluidic components appear in some hydraulic and pneumatic systems, including some automotive automatic transmissions. As digital logic has become more accepted in industrial control, the role of fluidics in industrial control has declined.Fluidic injection is being researched for thrust vectoring in aircraft jet engine nozzles, and for ships. Such systems divert thrust via fluid effects . Tests show that air forced into a jet engine exhaust stream can deflect thrust up to 15 degrees. Such nozzles are desirable for their lower: mass, cost (up to 50% less), inertia (for faster, stronger control response), complexity (mechanically simpler, no moving parts or surfaces), and radar cross section for Stealth. This will likely be used in many unmanned aircraft and 6th generation fighter aircraft.

Professor Nikolai Priezjev of the Department of Mechanical Engineering writes about fluidics and micro - fluidics  here .The transport and manipulation of small amounts of fluids are crucial for emerging technologies. A brisk demand for micro-devices, which are  used for the transportation of nanovolume  liquid samples, gave rise to a new exciting field called microfluidics. This field combines various  disciplines including engineering, chemistry, physics, and biology. The long range goal in modern technology is a reduction in size and the further development of microfluidic devices, which could be used for diagnoses of diseases, for the autonomous or remote detecting of biological and chemical  agents, and for gene and drug delivery.  

A very good introduction to microfluidics can be found at the wiki page. Microfluidics news is another kind of a aggregator for papers published on this subject . 

Food for thought :

  Is it possible to use constructal theory as a basis to design applications using microfluidics  ?? What would be the implications of doing so ?

Sources of information :

Wikipedia and Google .