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US 4,810,963 AGranted
Method for investigating the condition of a bacterial suspension through frequency profile of electrical admittance
AssigneePublic Health Laboratory Service Board
InventorsBarrie C. Blake-Coleman, David J. Clarke
Life of this patent
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Abstract
A method of investigating the condition of biological particles, in particular the fraction of viable cells in a bacteria population involves applying a voltage and monitoring the voltage induced by magnetic induction in a detector coil. The applied voltage is of a variable frequency alternating voltage and is preferably induced in the medium through a drive coil.
Claims6
A method of investigating the condition of a suspension of bacteria in a fluid medium, comprising the steps of:
- (a) positioning a sample of said suspension in a test cell having spaced electrodes;
- (b) applying an alternating voltage of selected frequency across said electrodes to cause a first current to flow in said suspension;
- (c) measuring a firs voltage induced by a first magnetic field associated with said first current in a detector coil placed adjacent the test cell;
- (d) repeating steps (b) and (c) with each of a plurality of different selected frequencies of said applied alternating voltage;
- (e) deriving, from analysis of values of said applied alternating voltage and said induced first voltage at said plurality of different frequencies, a first frequency profile of the admittance of the bacterial suspension;
- (f) preparing a sample of said fluid medium by removal of said bacteria from said suspension and positioning said sample in a test cell having spaced electrodes;
- (g) applying an alternating voltage of selected frequency across said electrodes to cause a second current to flow in said medium;
- (h) measuring a second voltage by a second magnetic field associated with said second current in a detector coil placed adjacent the test cell;
- (i) repeating steps (g) and (h) with each of a plurality of different selected frequencies of said applied alternating voltage;
- (j) deriving from analysis of values of said applied alternating voltage and said induced second voltage at said plurality of different frequencies to thereby generate a second frequency profile indicative of the admittance of the medium;
- and
- (k) comparing the first and second frequency profiles derived in step (e) and step (j), to thereby derive information relating to a condition of the bacteria in said suspension.
9 more elements
A method of investigating the condition of a suspension of bacteria in a fluid medium, comprising the steps of:
- (a) positioning said sample of said suspension in a test cell having disposed adjacent thereto a drive coil and a detector coil
- (b) applying an alternating current of selected frequency and constant amplitude to said drive coil to create a time-varying first magnetic field and thereby cause an alternating first current to flow in said suspension;
- (c) measuring a first voltage induced in a detector coil, by measuring a first magnetic field associated with said first current flowing in said suspension;
- (d) repeating steps (b) and (c) with each of a plurality of different selected frequencies of said drive coil current;
- (e) deriving, from analysis of values of said measured induced voltage at said plurality of frequencies, a first frequency profile of the admittance of the bacterial suspension;
- (f) preparing a sample of said fluid medium by the removal of bacteria from said suspension and positioning said sample in a test cell having a drive coil and a detector coil positioned adjacent thereto;
- (g) applying an alternating current of selected frequency and constant amplitude to said drive coil to create a time-varying second magnetic field and thereby to cause an alternating second current to flow in said medium;
- (h) measuring a second voltage induced in the detector coil by the second magnetic field associated with said alternating second current;
- (i) repeating steps (g) and (h) with a plurality of different selected frequencies of drive coil current;
- (j) deriving, from analysis of values of said measured induced second voltage at said plurality of frequencies, a second frequency profile indicative of the admittance of the medium;
- (k) comparing the first and second frequency profiles derived in step (e) and (j), to thereby derive information relating to a condition of the bacteria in said suspension.
8 more elements
Dependencies are inferred from the claim text.