Liquid level in capillary channel detection apparatus for control of flow in e.g. medical drip

摘要

The apparatus produces a control signal when the channel is full and includes two metallic electrodes (22,23), in galvanic contact with the liquid, for measurement of its conductivity. It is capacitively coupled to the input of an oscillator from whose output the control signal is derived. One electrode (23) is preferably sited near the inlet (21) of the main duct, and the other electrode (22) at the end of the larger overflow channel. Both passages and a chamber for the inlet electrode are machined, e.g. through anisotropic etching technology, in a flat plate (10), e.g. a silicon chip, of poor electrical conductivity, and the electrodes are deposited on a similar plate (20).