Ammonia and ammonium sensors

A sensor for a dialysis system, comprising:

• a fluid container for containing a dialysate fluid;
• a membrane positioned inside of the fluid container and having a variable optical property;
• and
• an optical reader positioned outside of the fluid container in a sensing relationship with the membrane.

An ammonia sensor for a dialysis system, comprising:

• a disposable unit having a fluid flow path;
• a ammonia sensitive membrane inside of the fluid flow path;
• and
• a membrane reader positioned outside of the fluid flow path in sensing relationship with the membrane.

A method of sensing ammonia in a dialysis system, comprising the steps of:

• providing an ammonia sensitive device inside of a fluid flow path having a fluid inlet and a fluid outlet;
• flowing dialysate through the fluid flow path;
• allowing the ammonia sensitive device to contact dialysate located in the fluid flow path;
• causing a color of a portion of the ammonia sensitive device to change in response to a concentration of ammonia in the dialysate;
• and
• identifying the color of the ammonia sensitive device from outside of the fluid flow path.

A method of performing dialysis, comprising the steps of:

• removing waste from a patient using dialysate fluid;
• positioning in the dialysate fluid a membrane that changes a parameter in relation to the level of a component in the dialysate fluid;
• and
• identifying the change in the parameter of the membrane.

A method of performing dialysis, comprising the steps of:

• removing waste from a patient using dialysate fluid and thereby forming spent dialysate;
• positioning in the spent dialysate an ammonia sensitive member which has a characteristic that changes in relation to the level of ammonia in the spent dialysate;
• and
• identifying a change in the characteristic of the ammonia sensitive member.