Devices for determining the relative spatial change in subsurface resistivities across frequencies in tissue

Abstract

Sensors for non-invasively determining tissue wetness/hydration based on relative changes in subsurface resistivities in tissue below the sensor when applied to a human body across different frequencies. A sensor including arrays of current-injecting and voltage-sensing electrodes may be placed on a subject's back to determine lung wetness. Sensors may be used as part of a systems and method for determining tissue water content, systems and methods for determining lung wetness, or the like. Sensors for determining relative changes in subsurface resistivities across frequencies and systems include arrays of electrodes used to determine relative changes in subsurface resistivities across frequencies may include pairs of current-injecting and voltage sensing electrodes.

What is claimed is: 
     
         1 . A device for non-invasively determining lung wetness, the device comprising:
 a sensor comprising a plurality of electrodes, wherein the plurality of electrodes in the active region are configured to form a plurality of pairs of current-injecting electrodes and a plurality of pairs of voltage detection electrodes;   a signal generator configured to apply a first drive signal comprising a first frequency and a second drive signal comprising a second frequency, wherein the first and second drive signals are applied to a first pair of electrodes of the sensor;   a processor configured to receive a first recorded signal correlating to the first frequency and a second recorded signal corrected to the second frequency, wherein the first and second recorded signals are received on a second pair of electrodes of the sensor; and   wherein the processor is further configured to determine lung wetness by operating on the first and second recorded signals independently of the patient's body geometry.