Wound therapy system and wound dressing with ph sensor

A wound treatment system having a sensor for measuring a pH level of a wound fluid from a wound area, the system comprising:

• a wound dressing comprising:
• a wound fluid manifold layer overlying the wound area and configured to permit and distribute a flow of wound fluid from the wound area,
• a drape layer disposed over the wound fluid manifold layer, and
• a tubing connection pad disposed on and connected to the drape layer;
• a negative pressure therapy unit configured to provide a negative pressure at the wound area;
• tubing coupling the negative pressure therapy unit to the tubing connection pad;
• and
• a sensor configured to measure a pH of the wound fluid from the wound area, the sensor coupled to the tubing connection pad and in fluid communication with the wound fluid from the wound area, the sensor comprising:
• a substrate having a first end and an opposite second end;
• a first electrode printed on the first end of the substrate and comprising a material having a changeable conductivity that changes according to a hydrogen ion concentration level, the first electrode being covered with a porous protective membrane coating comprising a sulfonated and/or carboxylated copolymer and being configured to permit hydrogen ion passage from the wound fluid to the first electrode while preventing direct contact between the wound fluid and the first electrode;
• a second electrode printed on the first end of the substrate and comprising a material having a fixed conductivity that does not change with the hydrogen ion concentration level;
• a third electrode printed on the second end of the substrate and being electrically connected to the first electrode via a first electrical trace;
• and
• a fourth electrode printed on the second end of the substrate and being electrically connected to the second electrode via a second electrical trace,
• wherein the sensor measures the pH level by measuring one or more voltage values between the third electrode and the fourth electrode.

A method of fabricating a sensor for measuring a pH level at a wound area, the method comprising:

• screen-printing a carbon-based ink or paste on a first end of a substrate comprising a polymeric material;
• depositing iridium oxide on the carbon-based ink or paste by electrodeposition to form a first electrode having a changeable conductivity that changes according to a hydrogen ion concentration level;
• depositing a porous protective membrane coating on the first electrode wherein the porous protective membrane coating comprises a sulfonated and/or carboxylated copolymer;
• screen-printing a second electrode on the first end of the substrate, wherein the second electrode comprises a material having a fixed conductivity that does not change according to a hydrogen ion concentration level;
• screen printing a third electrode on an opposite second end of the substrate such that the third electrode is electrically connected to the first electrode via a first electrical trace;
• and
• screen printing a fourth electrode on the second end of the substrate such that the fourth electrode is electrically connected to the second electrode via a second electrical trace,
• wherein the circuit measures the pH level by measuring one or more voltage values between the third electrode and the fourth electrode.