Sensor apparatus systems, devices and methods

A dialysis apparatus comprising a cassette for sensing liquid in the dialysis apparatus, the cassette comprising a housing having a plurality of fluid paths, each fluid path including

• a sensor element comprising a well for transmitting temperature and permitting conductivity sensing of fluid passing along the fluid path, wherein the well is adapted for interconnection with a sensor,
• wherein a first fluid path of the housing is configured to receive a first mixture of water and a bicarbonate buffer solution, and a second fluid path of the housing is configured to receive a second mixture of completed dialysate comprising the first mixture and an acid or electrolyte concentrate;
• wherein each fluid path comprises a conductivity sensing probe extending into the fluid path and spaced apart from the well.

A dialysis apparatus comprising a cassette for sensing liquid in the dialysis apparatus, the cassette comprising a housing having a plurality of fluid paths, each fluid path including

• a sensor element comprising a well for transmitting temperature and permitting conductivity sensing of fluid passing along the fluid path,
• wherein a first fluid flow path of the housing is configured to dialysate solution that is flowing to a dialyzer, and a second fluid flow path of the housing is configured to receive dialysate solution directed to drain or to a heating apparatus;
• wherein each well of the plurality of fluid paths is adapted for interconnection with a thermistor.