Peritoneal dialysis sensor apparatus systems, devices and methods

A method for determining the temperature and conductivity of dialysate in a peritoneal dialysis pump cassette, said pump cassette comprising a first region formed of a flexible membrane and a second region formed of a rigid material and not comprising a flexible membrane, said second region having at least two thermal wells formed in the rigid material and extending into a liquid flow path in the cassette, at least one of said thermal wells having at least a portion comprising an electrically conductive material configured for contacting a liquid contained in said liquid flow path, said method comprising the steps of:

• placing the cassette in a dialysis machine having at least two sensing probes, each sensing probe adapted to mate with one of the thermal wells;
• thermally coupling each thermal well with a sensing probe such that temperature and conductivity can be determined;
• transferring thermal and conductivity signals through at least 3 leads from at least one of said sensing probes;
• determining temperature and conductivity of a liquid contained in the liquid flow path using said signals;
• and
• comparing the conductivity determined to a preset conductivity level.

A disposable pump cassette for performing peritoneal dialysis comprising:

• a) a first side comprising a flexible membrane for pumping or directing liquid in the cassette;
• b) an opposing second side adapted and configured to receive a force urging at least a portion of the cassette against the flexible membrane when the cassette is mounted in a dialysis machine;
• and
• c) a third side not comprising a flexible membrane, wherein at least a portion of said third side:
• is not parallel to said first side;
• is not parallel to said opposing second side;
• spans at least a portion of the distance separating said first side from said opposing second side;
• and
• comprises a thermal well extending into a liquid path in the cassette, wherein
• the thermal well has a liquid side for making contact with liquid in the cassette and an opposing probe side for reversible mating with a sensing probe, said thermal well being thermally conductive between the liquid side and the probe side.

A disposable pump cassette for performing peritoneal dialysis comprising:

• a) a first region formed of a flexible membrane;
• and
• b) a second region, not co-planar with said first region, that is formed of a rigid material, does not comprise a flexible membrane and has at least two thermal wells formed in the rigid material and extending into a liquid flow path in the cassette;
• wherein
• each thermal well has a liquid side for making contact with liquid in the cassette and an opposing probe side for reversible mating with a sensing probe, each thermal well being thermally conductive between the liquid side and the probe side.