In-line sensors for dialysis applications

Abstract

A system for monitoring water quality for dialysis, dialysis fluids, and body fluids treated by dialysis fluids, is disclosed. The system uses microelectromechanical systems (MEMS) sensors for detecting impurities in input water or dialysis fluid, and in the prepared dialysate. These sensors may also be used to monitor and check the blood of the patient being treated. These sensors include ion-selective sensors, for ions such as ammonium or calcium, and also include amperometric array sensors, suitable for ions from chlorine or chloramines, e.g., chloride. These sensors assist in the monitoring of water supplies from a city water main or well. The sensors may be used in conjunction with systems for preparing dialysate solutions from water for use at home or elsewhere.

1 . A system for preparing dialysis fluid, comprising:
 a first purification vessel comprising a purification medium for water;   a device for pumping or measuring the water;   a heater for heating the water;   a mixing chamber configured for receiving the water from the device and for mixing the water with a concentrate to form a fresh dialysis solution;   a filter for filtering the fresh dialysis solution; and   a microelectromechanical systems (MEMS) sensor placed in fluid communication with an output from a vessel selected from the group consisting of the first purification vessel, the device, the heater, the mixing chamber and the filter.   
   
   
       2 . The system according to  claim 1 , wherein the MEMS sensor comprises an ion-selective sensor suitable for sensing two or more of an ion selected from the group consisting of ammonium, sodium, calcium, magnesium, potassium, carbonate, bicarbonate, hydrogen or hydronium, hydroxyl, chloramine and chloride. 
   
   
       3 . The system according to  claim 1 , wherein the MEMS sensor comprises an ion-selective sensor suitable for sensing at least two parameters selected from the group consisting of pH, calcium, total hardness, carbon dioxide and ammonia. 
   
   
       4 . The system according to  claim 1 , wherein the MEMS sensor is an amperometric sensor suitable for sensing chlorine and chloramines. 
   
   
       5 . The system according to  claim 1 , wherein the MEMS sensor further comprises a power source and a radio for remote communications. 
   
   
       6 . The system according to  claim 1 , wherein the water comprises fresh water or a spent dialysis solution. 
   
   
       7 . The system according to  claim 1 , further comprising a second purification vessel placed downstream of the first purification vessel, the second purification vessel further comprising a purification medium selected from the group consisting of a non-selective purification medium, a selective purification medium, an electro-deionization cartridge and an ion-exchange resin. 
   
   
       8 . The system according to  claim 1 , further comprising a water pump in operable communication with the first purification vessel or the heater. 
   
   
       9 . The system according to  claim 1 , wherein the MEMS sensor is suitable for measuring a plurality of substances in an aqueous solution or mixture. 
   
   
       10 . A system for preparing dialysis fluid, comprising:
 a first purification cartridge comprising a purification medium for water;   a heater for heating the water received from the first purification cartridge;   first and second pumps for pumping and metering first and second concentrates;   a mixing chamber configured for receiving the first and second concentrates from the first and second pumps and for mixing the first and second concentrates with the water to form a fresh dialysis solution;   a filter for filtering the fresh dialysis solution; and   a microelectromechanical systems (MEMS) sensor placed in fluid communication with an output of a vessel selected from the group consisting of the first purification cartridge, the heater, the mixing chamber and the filter,   wherein the MEMS sensor is suitable for sensing at least two substances in a stream selected from the group consisting of water from the first purification cartridge, the fresh dialysis solution and the filtered fresh dialysis solution.   
   
   
       11 . The system according to  claim 10 , wherein the MEMS sensor further comprises a radio transmitter for communicating with a controller of a dialysis machine. 
   
   
       12 . The system according to  claim 10 , further comprising an ultrafilter for removing bacteria and microorganisms from the water or from the dialysis solution. 
   
   
       13 . The system according to  claim 10 , further comprising a reverse osmosis filter for cleaning the water or the dialysis solution. 
   
   
       14 . The system according to  claim 10 , further comprising an ultraviolet light source for irradiating the water or dialysis solution, the ultraviolet light source placed upstream of the filter. 
   
   
       15 . The system according to  claim 10 , further comprising an air trap for removing air from the fresh dialysis solution. 
   
   
       16 . The system according to  claim 10 , wherein the water comprises fresh water or a spent dialysis solution. 
   
   
       17 . A method of preparing dialysis solution, comprising:
 furnishing a supply of water;   purifying the water in at least one pass through a purification medium;   heating the water;   adding the water to at least one dialysis concentrate to form a dialysis solution;   filtering the dialysis solution; and   sensing at least two characteristics of the water with a microelectromechanical systems (MEMS) sensor.   
   
   
       18 . The method of  claim 17 , wherein the MEMS sensor senses using an ion-selective membrane or an amperometric cell. 
   
   
       19 . The method of  claim 17 , further comprising sensing a characteristic of the dialysis solution with a second MEMS sensor. 
   
   
       20 . The method of  claim 17 , wherein the purification medium is selected from the group consisting of activated carbon and charcoal. 
   
   
       21 . The method of  claim 17 , wherein the dialysis solution formed comprises make-up for a spent dialysis solution, and further comprising sensing at least two characteristics of the spent dialysis solution with a MEMS sensor. 
   
   
       22 . The system according to  claim 17 , wherein the water comprises fresh water or a purified spent dialysis solution. 
   
   
       23 . A method of preparing dialysis solution, comprising:
 furnishing a supply of water and spent dialysate;   purifying the water and the spent dialysate in at least one pass through a purification medium, wherein the purification medium may be in one vessel or more than vessel;   heating the water;   adding the water and at least one dialysis concentrate to form a dialysis solution;   filtering the formed dialysis solution; and   sensing at least two characteristics of a stream selected from the group consisting of the water, the formed dialysis solution and the spent dialysis solution with a microelectromechanical systems (MEMS) sensor.   
   
   
       24 . The method of  claim 23 , further comprising sending a signal from the MEMS sensor to a remote controller. 
   
   
       25 . The method of  claim 23 , further comprising performing peritoneal dialysis or hemodialysis. 
   
   
       26 . The method of  claim 23 , further comprising removing air from the formed dialysis solution. 
   
   
       27 . A method of purifying dialysis solution, comprising:
 furnishing a supply of spent dialysate;   purifying the spent dialysate in at least one pass through a purification medium in a vessel to form a purified dialysate;   filtering the spent dialysate to form a filtered dialysate; and   sensing at least two characteristics of a stream selected from the group consisting of the spent dialysate, the purified dialysate and the filtered dialysate with a microelectromechanical systems (MEMS) sensor.   
   
   
       28 . The method of  claim 27 , wherein the method is accomplished with a portable dialysis system in which the vessel is a cartridge, and further comprising conducting dialysis while wearing the portable dialysis system. 
   
   
       29 . The method of  claim 27 , wherein the vessel adsorbs impurities from the spent dialysate and releases desirable ions into the spent dialysate as the spent dialysate passes through the vessel. 
   
   
       30 . The method of  claim 27 , further comprising making fresh dialysate from water and concentrate and adding the fresh dialysate to the filtered dialysate. 
   
   
       31 . A method for performing dialysis, comprising:
 providing a dialysis machine and a supply of dialysis fluid;   sensing and determining a composition of the dialysis fluid with a MEMS sensor suitable for sensing and detecting at least two ions in the dialysis fluid;   performing dialysis on a patient using the dialysis fluid;   sensing and determining a composition of the dialysis fluid after the step of performing dialysis with a MEMS sensor;   purifying the dialysis fluid after the step of performing dialysis;   sensing and determining a composition of the dialysis fluid after the step of purifying with a MEMS sensor; and   reusing the dialysis fluid if the composition of the dialysis fluid after the step of purifying is suitable for dialysis.   
   
   
       32 . The method of  claim 31 , wherein the steps of sensing and determining are conducted with a MEMS sensor comprising an ion-selective sensor suitable for sensing two ions selected from the group consisting of ammonium, sodium, calcium, magnesium, potassium, carbonate, bicarbonate, hydrogen or hydronium, hydroxyl, chloramine and chloride. 
   
   
       33 . The method of  claim 31 , wherein the MEMS sensor comprises an ion-selective sensor suitable for sensing at least two parameters selected from the group consisting of pH, calcium, total hardness, carbon dioxide and ammonia. 
   
   
       34 . The method of  claim 31 , wherein the MEMS sensor is an amperometric sensor suitable for sensing chlorine or chloramines. 
   
   
       35 . The method of  claim 31 , further comprising sending the compositions to a controller of the dialysis machine. 
   
   
       36 . The method of  claim 31 , wherein the step of conducting dialysis is accomplished with peritoneal dialysis or hemodialysis. 
   
   
       37 . The method of  claim 31 , wherein the dialysis is hemodialysis and further comprising sensing and determining a composition of blood of a patient with a MEMS sensor.