Allegro Technologies Limited

Alexander Shvets

Igor V Shvets

Juergen Osing

Sergei Makarov

Cecilia Franken

Jurgen Osing

There is provided a liquid droplet monitoring and measuring apparatus () for a liquid droplet dispensing system having a nozzle () with a dispensing tip (). The apparatus () comprises an inner chamber () surrounded by an outer shield (), preferably not in contact with each other. An RF oscillator electrically energizes the liquid through an electrode (). The inner chamber () is connected through pre-amplifiers (), band pass filters (conditioning amplifier () to a signal read-out device (). The operation of the apparatus is based on the measurement of the capacitance between the nozzle () and the inner chamber (). As a droplet () grows on the dispensing tip (), the capacitance between the nozzle () and the inner chamber () increases. Therefore, the signal detected and received by the signal read-out device () changes. This change is directly related to the volume of the droplet which can therefore be measured. In another embodiment, the liquid is not energized but is used to change the dielectric constant of a capacitor formed by, for example, the nozzle () and a substrate.

Apparatus and method for droplet measurements

A dispenser ( ) for liquid droplets of the order of 30 &mgr;l or less in volume. The dispenser ( ) comprises a metering valve body ( ) having a main bore ( ) connected by a pipe ( ) to a pressurised liquid delivery source (not shown). The body ( ) comprises a base ( ) from which is mounted a nozzle ( ) projecting above the base ( ) to form a valve seat ( ). An actuating coil assembly ( ) is mounted on the exterior of the body ( ) for moving a floating valve boss ( ) of a ferromagnetic material. Sensing coils ( ) are mounted around and spaced-apart along the body ( ) forming part of a valve boss detector. The valve boss detector acts as a positional movement detector so that the opening and closing of the valve can be accurately controlled and bouncing of the valve boss ( ) either against an end stop ( ) or on the valve seat ( ) can be greatly minimized, if not prevented fully, by careful operation of the actuating coil assembly ( ).

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Dublin, Ireland

Alexander Shvets