Breakthrough in fluid control

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April 2001 Sensors & Transducers

In response to the ever increasing range of applications dependant upon accurate measurement of sub-microlitre to nanolitre liquid quantities for analytical, research and industrial purposes, Bürkert-Contromatic AG International has introduced a revolutionary new micro system capable of dispensing 50 nl to 100 µl across a wide range of fluids.

To achieve consistent and dependable control of such small volumes, the Bürkert micro system uses a unique combination of micro flow sensor and flipper solenoid valve with isolating diaphragm. The sensor is based on the measurement of pressure differential across an integrated fluidic restriction. A silicon chip consisting of two piezo-resistive pressure sensors forms the actual flow sensor device. Both the electrical and fluidic interfaces can be customised according to individual user needs. The sensor is mounted in a hybrid module with dedicated programmable electronics for primary signal conditioning and the measurement of pressure, temperature and flow in both directions. Higher-level conditioning is based on applying a correction for the temperature dependence of the liquid viscosity.

The fully compensated sensor module allows for measuring flow rate up to 5 µl/s FS with an accuracy better than 1% FS of the flow rate at temperatures from 20 to 50°C. The valve is a micro version of Bürkert's well-proven flipper design actuating mechanism, which operates an isolating diaphragm separating the actuator and the coil from the fluid.

Characteristically, this design eliminates friction with no risk of sticking, and a durable Simriz diaphragm provides high reliability and long service life. A minimal internal volume ensures the valve is easily purged so the risk of cross-contamination is eliminated, thus making the system ideal for the control of critical fluids.

The Bürkert micro system is well suited to high-speed liquid dosing instruments in which sensor speed, small size and consistent accuracy are of prime importance. Target applications include multichannel dispensing instruments for reagent dosing in pharmaceutical and cosmetics development and manufacture, medical diagnostics, pathology and scientific research.

Typically, the trend in all these areas is towards miniaturisation of liquid handling systems.

The Bürkert micro system's hybrid assembly techniques permit the integration of the sensors and intelligent signal conditioning to be located very close to the point of use, thus increasing speed by reducing dead volume and allowing for a high density of measurement points.

The valves are suitable for compact manifold mounting, and fully customised manifolds are available to satisfy specific application requirements, including dead volume-free designs.

The addition of micro system to Bürkert-Contromatic's ever expanding range of fluid control solutions are a further indication of its commitment to a technology it has pioneered for more than fifty years.

Bürkert-Contromatic

(011) 397 2900

[email protected]

www.burkert.co.za

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