Phase change sensor

Abstract

A device is disclosed which is a highly sensitive and selective sensor. The device is comprised of a sensor material secured into a fixed position on substrate, a deformable arm and a signaling component which creates a detectable signal in response to movement of the arm. The sensitivity of the device is enhanced by using a sensor material which undergoes a dramatic change in volume which may be accompanied by a phase change in response contact with a target such a molecule of interest. The selectivity of the device is enhanced by incorporating highly specific binding receptors (e.g. antibodies) into the sensor material which receptors bind to specific targets (e.g. peptide epitopes). The binding of the target molecule to the receptor causes the sensor material to change dramatically in volume thereby moving the arm causing the signaling component (e.g. a piezoresistor) to create a detectable signal (e.g. change in resistance) thereby indicating the present of the target.

1 . A method for detecting a change in osmolality of saliva, comprising 
 providing a polymer responsive by a change in volume to a change in osmolality;    contacting the polymer with saliva from a subject; and    detecting a change in saliva osmolality by monitoring the polymer for an increase or decrease in polymer volume.    
     
     
         2 . The method of  claim 1 , wherein the polymer is a cross-linked hydrogel.  
     
     
         3 . The method of  claim 1 , wherein said detecting comprises monitoring the polymer for a decrease in polymer volume to detect a saliva osmolality.  
     
     
         4 . The method of  claim 3 , wherein the saliva osmolarity is in the range of 50-200 mOsm.  
     
     
         5 . The method of  claim 1 , wherein said detecting comprises monitoring the polymer for an increase in polymer volume.  
     
     
         6 . The method of  claim 5 , wherein the saliva osmolarity is in the range of 50-200 mOsm.  
     
     
         7 . The method of  claim 1 , wherein said detecting comprises monitoring the polymer for a decrease in polymer volume to detect dehydration.  
     
     
         8 . The method of  claim 1 , wherein said providing comprises providing a polymer responsive to a change in osmolality in the range of 50-200 mOsm.  
     
     
         9 . The method of  claim 1 , wherein said polymer is comprised of one or more monomers selected from the group consisting of an acrylamide or a hydroxy alkyl acrylate.  
     
     
         10 . The method of  claim 1 , wherein said polymer comprises a polymer selected from the group consisting of poly(acrylic acids), poly(methacrylic acids), poly(acrylamides), poly(vinyl alcohols), and poly(ethylene oxides).  
     
     
         11 . The method of  claim 1 , wherein said polymer is selected from the group consisting of hydroxyethylacrylate, acrylamide, methacrylamide, n,n-dimethylacrylamide, hydroxypropyl acrylate, and n-isopropylamide.  
     
     
         12 . A method for monitoring hydration level in a subject, comprising 
 providing a polymer responsive by a change in volume to a change in osmolality,    contacting the polymer with saliva from a subject; and    monitoring hydration level in the subject by detecting a change in polymer volume.    
     
     
         13 . The method of  claim 12 , wherein the polymer is a cross-linked hydrogel.  
     
     
         14 . The method of  claim 12 , wherein said detecting comprises monitoring the polymer for a decrease in polymer volume to detect a saliva osmolality.  
     
     
         15 . The method of  claim 14 , wherein the saliva osmolarity is in the range of 50-200 mOsm.  
     
     
         16 . The method of  claim 12 , wherein said detecting comprises monitoring the polymer for an increase in polymer volume.  
     
     
         17 . The method of  claim 16 , wherein the saliva osmolarity is in the range of 50-200 mOsm.  
     
     
         18 . The method of  claim 12 , wherein said detecting comprises monitoring the polymer for a decrease in polymer volume to detect dehydration.  
     
     
         19 . The method of  claim 12 , wherein said providing comprises providing a polymer responsive to a change in osmolality in the range of 50-200 mOsm.  
     
     
         20 . The method of  claim 12 , wherein said polymer is comprised of one or more monomers selected from the group consisting of an acrylamide or a hydroxy alkyl acrylate.  
     
     
         21 . The method of  claim 12 , wherein said polymer comprises a polymer selected from the group consisting of poly(acrylic acids), poly(methacrylic acids), poly(acrylamides), poly(vinyl alcohols), and poly(ethylene oxides).  
     
     
         22 . The method of  claim 12 , wherein said polymer is selected from the group consisting of hydroxyethylacrylate, acrylamide, methacrylamide, n,n-dimethylacrylamide, hydroxypropyl acrylate, and n-isopropylamide.