Patent ID: 7416706
Filing Date: 2008-08-26
Classification: B01L,G01F,G01N

Abstract:
1. A level sensor apparatus for detecting contact of a pipetting needle with a liquid contained in a vessel, said apparatus comprising: a sensor head having a mechanical resonance frequency and including: an electrical signal generator for generating a driving signal and for applying the signal to the electromechanical transducer to cause vibration of said pipetting needle at the resonance frequency; a measurement device for measuring a parameter of a vibration signal provided by the electromechanical transducer, the vibration signal being representative of a vibration of the pipetting needle when it is driven by the driving signal; and electronic circuit for (i) evaluating variation of the vibration signal with time, (ii) detecting contact of the pipetting needle with a liquid contained in the vessel, and (iii) providing a resulting signal representative of the result of said evaluation.