Dissolved gases in liquids can significantly disrupt chemical and biotechnological processes: pressure or temperature fluctuations can potentially lead to outgassing of the liquid, i.e. the formation of tiny gas bubbles. These can falsify sensor measurements, impair the compressibility of the liquid and at worst even cause system failure. To be on the safe side, the liquid should first be degassed. However, existing degassers are expensive and require a vacuum connection for operation – usually only available from a well-equipped laboratory.
Fraunhofer EMFT researchers developed a self-sufficient micro-degasser which is capable of removing both gas bubbles and dissolved gas from a liquid. The liquid is pumped in a porous tube through a low-pressure chamber in which the dissolved gas diffuses. A silicon micromembrane pump developed at Fraunhofer EMFT is integrated in the degasser. This can build up very high levels of negative pressure of up to -55 kPa – sufficient to generate the necessary negative pressure in the chamber and maintain this during degassing. Only a mains connection is required for operation, which significantly expands the range of potential uses. Researchers also integrated a pressure sensor in the chamber which ensures that the pump is not activated until a defined level of negative pressure is reached in the chamber. This saves energy and extends the service life of the pump.
On tests to date, a functional demonstrator of the micro-degasser has shown a degassing efficiency of approx. 50% at flow rates of 50 - 200 μl/min. It has two standard luer connections for input and output as well as a connector for voltage control of the micropump, enabling the system to be integrated in most units without undue effort.