公开(公告)号：DE2438401A1

公开(公告)日：1975-02-27

申请号：DE2438401

申请日：1974-08-09

Applicant: COULTER ELECTRONICS

Inventor： LIEDHOLZ GERHARD ADOLPH ,  COULTER WALLACE HENRY ,  HOGG WALTER ROBERT

IPC: G01N15/12 ,  G01N33/49 ,  G01R27/26 ,  G01N27/02

Abstract: The electrical sensing circuitry includes a power supply and a signal-detecting circuit which are coupled through the resistance of an electrolyte in a liquid in an aperture of a particle-analyzing device between sensing electrodes positioned on either side of the aperture. The liquid containing an electrolyte and the passage of a liquidborne particle through the aperture causes a change in the resistance of the aperture thereby generating a signal which is detected by the signal-detecting circuit. The parameters of the circuit elements are chosen to provide circuit relationships which render the particle-generated signal independent of the diameter of the aperture. This is achieved by utilizing a power source having a low output impedance and a signal-detecting circuit which has a low input impedance for both D.C. and A.C., namely, at the signal frequencies of the signals sensed. The electrical circuitry also may include a conductivity monitoring circuit which may utilize one or more of the sensing electrodes and/or additional electrodes for monitoring changes in conductivity of the electrolyte and for relating these changes in conductivity to the particle-generated signals sensed by the signal-detecting circuit to alter those signals so as to render them independent of electrolyte resistivity.