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EP-3941346-B1 - SYSTEMS AND METHODS FOR MEASURING TISSUE IMPEDANCE

EP3941346B1EP 3941346 B1EP3941346 B1EP 3941346B1EP-3941346-B1

Inventors

  • BRAY, David, Michael
  • QUINTANAR, FELIX, CLARENCE

Dates

Publication Date
20260506
Application Date
20200310

Claims (13)

  1. A monitoring and/or therapy apparatus comprising: a plurality of excitation pads configured to apply an excitation signal to tissue of a patient, the plurality of excitation pads connected to an electronic circuit configured to communicate the excitation signal to the plurality of excitation pads, the electronic circuit comprising circuitry configured to condition the excitation signal; at least one measurement sensor configured to measure a voltage of the tissue in response to application of the excitation signal; wherein the plurality of excitation pads and the at least one measurement sensor are positioned on a substrate configured to be placed in a wound; and a controller in communication with the plurality of excitation pads, the electronic circuit, and the at least one measurement sensor, the controller configured to: generate the excitation signal, measure a current of the excitation signal after it has been communicated through at least circuitry configured to condition the excitation signal and before the excitation signal is applied to the tissue via the plurality of excitation pads, and determine impedance of the tissue based at least in part on the voltage measured by the at least one measurement sensor and the current of the excitation signal, wherein measurement of the current of the excitation signal after it has been communicated through at least circuitry configured to condition the excitation signal allows for removal of an impedance of at least circuitry configured to condition the excitation signal from the determined impedance of the tissue; and wherein the plurality of excitation pads are configured to be capacitively-coupled with no direct conductive pathway to the tissue, wherein the apparatus further comprises an excitation measurement circuit connected to the plurality of excitation pads, the controller, and the electronic circuit, wherein the excitation measurement circuit is configured to measure the current and the voltage of the excitation signal after it has been communicated through at least circuitry configured to condition the excitation signal.
  2. The apparatus of claim 1, wherein the circuitry configured to condition the excitation signal is configured to one or more of filter or buffer the excitation signal.
  3. The apparatus of any one of the preceding claims, wherein the at least one measurement sensor comprises at least two measurement sensors, and wherein the apparatus further comprises a selection circuit connected to each of the at least two measurement sensors, the selection circuit configured to select a voltage measured between the at least two measurement sensors.
  4. The apparatus of claim 3, where the controller is further configured to receive the selected voltage from the selection circuit and determine the impedance based at least in part on the selected voltage.
  5. The apparatus of claim 3 or claim 4, where the controller is further configured to communicate one or more selection signals to the selection circuit to select the measured voltage.
  6. The apparatus of claim 5, wherein the selection circuit selects the measurement sensor based at least in part on the one or more selection signals received from the controller.
  7. The apparatus of any one of the preceding claims, wherein the plurality of excitation pads comprises two excitation pads.
  8. The apparatus of any one of the preceding claims, wherein the at least one measurement sensor comprises eight measurement sensors.
  9. The apparatus of any one of the preceding claims, wherein the excitation signal comprises a differential signal.
  10. The apparatus of any one of the preceding claims, wherein the substrate is substantially flexible so as to conform to the wound.
  11. The apparatus of any one of the preceding claims, wherein the electronic circuit is further configured to at least one of filter or buffer the excitation signal before it is applied to the tissue via the plurality of excitation pads.
  12. The apparatus of claim 11, wherein the controller is further configured to measure the current of the excitation signal after the electronic circuit at least one of filters or buffers the excitation signal.
  13. The apparatus of any one of the preceding claims, wherein the electronic circuit is further configured to convert the excitation signal into a differential signal.

Description

Field Embodiments of the present disclosure relate to apparatuses, systems, and methods for the monitoring and/or treatment of tissues using one or more sensors, including measuring tissue impedance. Description of the Related Art Nearly all areas of medicine may benefit from improved information regarding the state of the tissue, organ, or system to be treated, particularly if such information is gathered in real-time during treatment. Many types of treatments are still routinely performed without the use of sensor data collection; instead, such treatments rely upon visual inspection by a caregiver or other limited means rather than quantitative sensor data. For example, in the case of wound treatment via dressings and/or negative pressure wound therapy, data collection is generally limited to visual inspection by a caregiver and often the underlying wounded tissue may be obscured by bandages or other visual impediments. Even intact, unwounded skin may have underlying damage that is not visible to the naked eye, such as a compromised vascular or deeper tissue damage that may lead to an ulcer. Similar to wound treatment, during orthopedic treatments requiring the immobilization of a limb with a cast or other encasement, only limited information is gathered on the underlying tissue. In instances of internal tissue repair, such as a bone plate, continued direct sensor-driven data collection is not performed. Further, braces and/or sleeves used to support musculoskeletal function do not monitor the functions of the underlying muscles or the movement of the limbs. Outside of direct treatments, common hospital room items such as beds and blankets could be improved by adding capability to monitor patient parameters. Therefore, there is a need for improved sensor monitoring, particularly through the use of sensor-enabled substrates which can be incorporated into existing treatment regimes. Relevant prior art is disclosed in patent publications EP1754441B1, WO2019020666A1, WO2019020551A1, EP1138259A2 and EP1118308A1. SUMMARY OF THE INVENTION The invention is defined in the appended set of claims. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present disclosure will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which: FIG. 1A illustrates a negative pressure wound treatment system;FIG. 1B illustrates a wound dressing;FIG. 1C illustrates a negative pressure wound treatment system employing a flexible fluidic connector and a wound dressing capable of absorbing and storing wound exudate;FIG. 1D illustrates a negative pressure wound treatment system employing a flexible fluidic connector;FIG. 1E illustrates a negative pressure wound treatment system employing a flexible fluidic connector and a wound dressing capable of absorbing and storing wound exudate;FIG. 1F illustrates of a negative pressure wound therapy system;FIG. 1G illustrates a wound treatment system employing a wound dressing capable of absorbing and storing wound exudate to be used without negative pressure;FIG. 2 illustrates a sensor array illustrating the sensor placement incorporated into a wound dressing;FIG. 3A illustrates a flexible sensor array including a sensor array portion, a tail portion and a connector pad end portion according;FIG. 3B illustrates flexible circuit boards with different sensor array geometries;FIG. 3C illustrates the sensor array portion of a sensor array shown in FIG. 3B;FIG. 3D illustrates a flexible sensor array incorporated into a perforated wound contact layer;FIG. 3E illustrates a control module;FIG. 4A illustrates a perspective view of a substrate supporting electronic components;FIG. 4B illustrates perspective view of a perforated substrate supporting electronic components;FIG. 5 is a schematic diagram of a wound monitoring and/or therapy system for determining impedance or conductance of tissue of a patient;FIG. 6A is a schematic diagram of a wound monitoring and/or therapy system for determining impedance or conductance of tissue of a patient;FIG. 6B is an example detailed schematic diagram of the electronic circuit 504 of the wound monitoring and/or therapy system of FIG. 6A;FIG. 6C is an example detailed schematic diagram of the excitation measurement circuit of the wound monitoring and/or therapy system of FIG. 6A;FIG. 6D is an example detailed schematic diagram of the selection circuit of the wound monitoring and/or therapy system of FIG. 6A;FIG. 6E is an example detailed schematic diagrams of a measurement sensor circuit of the wound monitoring and/or therapy system of FIG. 6A.FIG. 7 is a flow diagram illustrative of a routine for determining an impedance or conductance of tissue;FIG. 8 illustrates an example schematic configuration of a wound dressing; andFIG. 9 illustrates current density between excitation pads. DETAILED DESCRIPTION Embodiments disclosed herein relate to apparatuses and methods of at least one of monitoring or treating biological tiss