Method and sensor for determining a value indicating the impedance of a suspension

Patent metadata

Field	Value
Publication number	US-2022136990-A1
Application number	US-201917297571-A
Country	US
Kind code	A1
Filing date	Nov 29, 2019
Priority date	Nov 30, 2018
Publication date	May 5, 2022
Grant date	—

Abstract

A method for determining a value indicative of the impedance of a suspension in the framework of impedance spectroscopy comprises the following steps: generating an excitation current through the suspension, oscillating at an excitation frequency; determining a first impedance measurement value on the basis of the excitation current and a first voltage at a first pair of measurement electrodes; determining a second impedance measurement value on the basis of the excitation current and a second voltage at a second pair of measurement electrodes; determining the value indicative of the impedance of the suspension by correlating the first impedance measurement and the second impedance measurement.

First claim

1 . A method for determining a value indicative of the impedance of a suspension in the framework of an impedance spectroscopy, comprising the following steps:
generating an excitation current through the suspension, the excitation current oscillating at an excitation frequency, determining a first impedance measurement value on the basis of the excitation current and a first voltage at a first pair of measurement electrodes, determining a second impedance measurement value on the basis of the excitation current and a second voltage at a second pair of measurement electrodes, determining the value indicative of the impedance of the suspension by correlating the first impedance measurement value and the second impedance measurement value.

2 . The method according to claim 1 ,
wherein said first pair of measurement electrodes comprises a first measurement electrode and a second measurement electrode, and wherein said second pair of measurement electrodes comprises said first measurement electrode and a third measurement electrode, or wherein the first pair of measurement electrodes comprises a first measurement electrode and a second measurement electrode, and wherein the second pair of measurement electrodes comprises a third measurement electrode and a fourth measurement electrode.

3 . (canceled)

4 . The method according to claim 1 , wherein determining the value indicative of the impedance of the suspension comprises determining the difference between the first impedance measurement value and the second impedance measurement value, or comprises determining the difference between a first adjusted impedance value and a second adjusted impedance value, wherein the first adjusted impedance value and the second adjusted impedance value are obtained by applying a correction function to the first impedance measurement value and the second impedance measurement value, the correction function preferably representing the transmission behavior of the measurement arrangement.

5 . The method according to claim 1 , wherein determining the value indicative of the impedance of the suspension comprises determining the difference between a first geometry factor and a second geometry factor, wherein the first geometry factor represents the measurement geometry of the first pair of measurement electrodes and wherein the second geometry factor represents the measurement geometry of the second pair of measurement electrodes.

6 . The method according to claim 1 , wherein determining the value indicative of the impedance of the suspension is carried out according to the following formula:

Z
=

k
⁢

1

(

λ
1

-

λ

2
⁢

)

⁢

(

G
el

-
1

⁡

(

Z
sig

)



1

-

G
el

-
1

⁡

(

Z
sig

)



2

)

,

wherein Z sig | 1 denotes the first impedance measurement value, Z sig | 2 denotes the second impedance measurement value, G el −1 denotes a correction function representing the transmission behavior of the measurement arrangement, λ 1 denotes a first geometry factor representing the measurement geometry of the first pair of measurement electrodes, λ 2 denotes a second geometry factor representing the measurement geometry of the second pair of measurement electrodes, and k denotes a proportionality constant.

7 . The method according to claim 1 , further comprising:
measuring the first voltage at the first pair of measurement electrodes, and measuring the second voltage at the second pair of measurement electrodes, wherein measuring the first voltage and measuring the second voltage are performed substantially simultaneously, or further comprising: measuring the first voltage at the first pair of measurement electrodes, and measuring the second voltage at the second pair of measurement electrodes, wherein measuring the first voltage and measuring the second voltage are performed in a time-shifted manner.

8 - 9 . (canceled)

10 . The method according to claim 1 , wherein determining the first impedance measurement value and determining the second impedance measurement value comprises:
sampling the excitation current, sampling the first voltage, and sampling the second voltage wherein the method further comprises the steps of: setting a first sampling rate for sampling the excitation current, setting a second sampling rate for sampling the first voltage, and setting a third sampling rate for sampling the second voltage, wherein the first sampling rate, the second sampling rate and the third sampling rate are set to at least 4 times the excitation frequency of the excitation current, in particular to substantially 4 times the excitation frequency of the excitation current.

11 - 12 . (canceled)

13 . The method according to claim 10 , wherein the step of determining the first impedance measurement value comprises performing a first complex Fourier transform on the basis of the sampling values of the excitation current and the sampling values of the

Assignees

• Hamilton Bonaduz Ag

Inventors

• Verschinin Valentin
• Imhof Manuel

Classifications

• G01R1/06

  Measuring leads; Measuring probes (G01R19/145, G01R19/165 take precedence) · CPC title

• G01N33/48735

  Investigating suspensions of cells, e.g. measuring microbe concentration (by chemical means C12Q1/04; colony counters C12M1/34; concentration of particle suspensions in general G01N15/06) · CPC title

• G01N27/028 Primary

  Circuits therefor (measuring impedance per se G01R27/02) · CPC title

• G01R27/22

  Measuring resistance of fluids · CPC title

• G01N27/026 Primary

  Dielectric impedance spectroscopy (electrochemical impedance spectroscopy for measuring corrosion G01N17/02) · CPC title