Interferent and baseline drift correcting sensor system

Abstract

A sensor system that removes responses from an interferent and/or corrects for baseline drift of a sensor to determine a presence, a concentration or a change in concentration of a target material in a gaseous environment. Fluid flowing into the system may be directed by a valve arrangement to either a first fluid flow path or a second fluid flow path. The target material may be absorbed by a filter material in the first fluid flow path. Fluid flowing along the second gas flow path passes directly to the sensor. Responses of the sensor to fluids from the first and second fluid flow paths may be used to determine a presence, concentration or change in concentration of the target material.

1 . A sensor system configured to determine a presence, a concentration or a change in concentration of a target material in a gaseous or liquid environment, comprising:
 a sensor configured to respond to the target material;   an inlet configured to draw gas from an environment into the apparatus; and   a valve arrangement configured to direct fluid drawn from the environment to a first fluid flow path in fluid communication with the sensor or to a second fluid flow path in fluid communication with the sensor.   
     
     
         2 . The system according to  claim 1 , wherein the first fluid flow path is disposed between the sensor and a first valve of the valve assembly and the second fluid flow path is disposed between the sensor and a second valve of the valve assembly. 
     
     
         3 . The system according to  claim 1  wherein the first and second fluid flow paths are disposed between the sensor and a three-way valve of the valve assembly. 
     
     
         4 . The system according to  claim 1 , wherein the system further comprises a third fluid flow path in fluid communication with the sensor and disposed between a valve of the valve arrangement and the sensor. 
     
     
         5 . The system according to  claim 1 , wherein a water reservoir in fluid communication with the first fluid flow path is disposed in fluid communication with the first fluid flow path between the valve assembly and the sensor. 
     
     
         6 . The system according to  claim 5 , wherein the water reservoir is in fluid communication with the second fluid flow path. 
     
     
         7 . The system according to  claim 6 , wherein a saturated salt solution is disposed in the water reservoir. 
     
     
         8 . The system according to  claim 6  wherein a desiccant is disposed between the inlet and the valve assembly. 
     
     
         9 . The system according to  claim 6  wherein a desiccant is disposed in the second fluid flow path. 
     
     
         10 . The system according to  claim 1 , wherein the sensor is a thin film transistor. 
     
     
         11 . The system according to  claim 1 , wherein a filter material for removing the target material from the fluid is disposed in the first fluid flow path. 
     
     
         12 . The system according to  claim 11 , wherein the filter material is a desiccant filter material. 
     
     
         13 . The system according to  claim 11 , wherein the filter material comprises silica gel. 
     
     
         14 . The system according to  claim 11 , wherein the filter material is a molecular sieve. 
     
     
         15 . The system according to  claim 1  wherein the system is a gas sensor system and the sensor is a gas sensor. 
     
     
         16 . A kit for forming the sensor system according to  claim 1 , comprising a sensor, a fluid inlet, a first fluid flow path, a second fluid flow path and at least one valve for forming the valve arrangement. 
     
     
         17 . (canceled) 
     
     
         18 . A method of determining a presence, concentration or change in concentration of a target material in a gaseous or liquid environment, the method comprising:
 measuring, in either order, a first response and a second response of a sensor of a sensor system wherein the sensor is configured to respond to the target material and wherein the sensor system comprises:   the sensor;   an inlet configured to draw gas from an environment into the apparatus; and   a valve arrangement configured to direct fluid drawn from the environment to a first fluid flow path in fluid communication with the sensor or to a second fluid flow path in fluid communication with the sensor,   wherein the first response is a response of the sensor to fluid from the first flow path which has been treated to remove the target material from the fluid and the second response is a response of the sensor to fluid from the second flow path which has not been treated to remove the target material from the fluid; and   subtracting the first sensor measurement or a derivative thereof from the second sensor measurement or a derivative thereof.   
     
     
         19 . The method according to  claim 18 , wherein a filter material for removing the target material from the fluid is disposed in the first fluid flow path. 
     
     
         20 . The method according to  claim 18 , wherein the first sensor measurement is generated by exposing the sensor to a sample from the fluid environment which has been exposed to a desiccant filter material and rehydrated. 
     
     
         21 . (canceled) 
     
     
         22 . The method according to  claim 18 , wherein the target material is 1-methylcyclopropene. 
     
     
         23 - 34 . (canceled)