A method and apparatus for dielectric diagnostic analysis of human and non-human cells or tissue functions by measuring the response of the cells or tissue to an applied excitation signal in a time period less than the polarization relaxation time period of a domain group of the cells or tissue under examination.

The deformability measurement chamber is subdivided by a foil into two chamber spaces. The foil has a passage opening, the diameter of which is smaller than the diameter, at rest, of a red blood corpuscle. A static pressure gradient exists between the two chamber spaces, so that a flow takes place from one chamber space to the other. In the region of the passage opening there is situated on each side of the foil an electrode, which is connected to an alternating voltage source. In order to achieve a measurement signal which is approximately one order of magnitude greater, at a given alternating voltage frequency, a current-measuring operational amplifier is disposed in the connecton of one electrode to the voltage source.

A particle analyzing apparatus for studying a stream of membrane-sheathed particles in liquid suspension wherein, for a given particle, a first particle pulse signal is obtained from a first sensing aperture having a first low frequency electrical field with an intensity below that causing particle electrical breakdown; a second particle pulse signal is obtained from a second sensing aperture having a second low frequency electrical field with an intensity equal to or greater than that causing particle electrical breakdown; a third particle pulse signal is obtained from one of the sensing apertures by having a high frequency electrical field therein or, alternatively, from a third sensing aperture having a third low frequency electrical field with a second and different intensity equal to or greater than that causing particle electrical breakdown. The three signals are correlated on a cell by cell basis and are used to determine the particles' apparent breakdown field intensity size and opacity, which in turn can yield particle volume, shape and internal conductivity.

Analytical apparatus is arranged for increased sensitivity in determining a desired characteristic by decreasing the sensitivity to extraneous noise, essentially as common mode signal, while treating the desired signal differentially. Test signal is applied to apparatus comprising an electrochemical cell containing electrolyte in which a pair of matched working electrodes are equispaced from a counter electrode and from a reference electrode. The working electrodes conduct different values of current, the difference being a measure of characteristic of material making up the electrolyte. The signal applied between the counter and the working electrodes is varied over a predetermined range. The potential between the working electrodes is established at zero for basic operation, but a fixed biasing potential is established between the two working electrodes for a given experiment in which the test signal is varied. The biasing potential is usually relatively small and the current flow difference under study is likewise very small. The data output signal which is proportional to the small difference in the currents, is amplified in stable high gain circuitry.

A paraffin monitor includes a pair of probes which are immersed in a medium having paraffin contained therein. A circuit is connected to the probes which provides an output voltage. The characteristics of the electric circuit changes over a period of time, causing a corresponding change in the voltage output, in accordance with a change in the amount of paraffin on the probes.