Method and apparatus to sense hydration level of a person

Abstract

A hydration sensor or sensing element is configured to measure the hydration level of a user. The sensing element can include a water-permeable material positioned in between two water-impermeable material. The sensing element can be coupled to a bottle of fluid, or a carrier with a timer. The sensing element can be incorporated into a handheld device. The sensing element can be a disposable element, an element applicable for more than one-time use, or a re-usable element. The sensing element or sensor can be calibrated for a specific user or a group of users. One or more additional sensors that do not measure hydration level of the user can be coupled to a hydration sensing element to determine the amount of fluid consumption for the user in different conditions.

What is claimed is: 
     
         1 . A disposable hydration sensing element for measuring the hydration level of a user based on the user's saliva, the sensing element comprising:
 a sheet of water-permeable material having a first side and a second side, with a chemical compound at least coupled to the first side;   a first sheet of water-impermeable material coupled to the first side of the water-permeable material; and   a second sheet of water-impermeable material coupled to the second side of the water-permeable material,   wherein the hydration sensing element includes at least one aperture to allow saliva to reach the chemical compound from the at least one aperture,   wherein the chemical compound, at least due to contact with saliva, changes at least a portion of the water-permeable material, and the change is observable from at least a portion of one of the sheets of the water-impermeable material,   wherein at least a portion of the disposable sensing element is to be placed in the mouth of the user to measure the hydration level of the user, and   wherein the disposable hydration sensing element further includes an indicator to provide an indication regarding the hydration level of the user, based on time duration regarding the observable change of the water-permeable material, after the disposable hydration sensing element is placed in the mouth of the user.   
     
     
         2 . A disposable hydration sensing element as recited in  claim 1 , wherein the at least one aperture includes at least an edge of the water-permeable material that is exposed so that saliva is allowed to reach the chemical compound from the edge, or an opening on the first or the second sheet of water-impermeable material so that saliva is allowed to reach the chemical compound through the opening, if the disposable hydration sensing element is placed in the mouth of the user. 
     
     
         3 . A disposable hydration sensing element as recited in  claim 1 ,
 wherein the disposable hydration sensing element is connected to a plurality of similar elements to form a stack, and   wherein each of the elements of the stack is to be used individually for measuring hydration level.   
     
     
         4 . A disposable hydration sensing element as recited in  claim 1 , wherein the change includes forming a color patch on the water-permeable material at least due to the chemical compound on contact with saliva. 
     
     
         5 . A disposable hydration sensing element as recited in  claim 1 , wherein the indicator is on the second side of the sheet of water-permeable material. 
     
     
         6 . A disposable hydration sensing element as recited in  claim 5 ,
 wherein the indicator includes a plurality of identifiers, with each identifier spaced from the aperture by a different amount,   wherein the change includes forming a color patch on the water-permeable material at least due to the chemical compound on contact with saliva, and   wherein the hydration level of the user depends on the identifier furthest away from the aperture that the color patch reaches after the disposable hydration sensing element is placed in the mouth of the user for a predetermined duration of time.   
     
     
         7 . A disposable hydration sensing element as recited in  claim 1 ,
 wherein the indicator includes a plurality of identifiers, with each identifier spaced from the aperture by a different amount, and   wherein the hydration level of the user depends on the identifier furthest away from the aperture that the changed portion of the water-permeable material extends to after the disposable hydration sensing element is placed in the mouth of the user for a predetermined duration of time.   
     
     
         8 . A disposable hydration sensing element as recited in  claim 1 ,
 wherein the indicator is on the second side of the sheet of water-permeable material,   wherein the chemical compound is a powder, and   wherein the second sheet of water-impermeable material is substantially transparent at least in the area of the indicator.   
     
     
         9 . A disposable hydration sensing element as recited in  claim 1 ,
 wherein the indicator is on the second side of the sheet of water-permeable material,   wherein the indicator includes a plurality of identifiers, with each identifier spaced from the aperture by a different amount,   wherein the second sheet of water-impermeable material is substantially transparent at least in the area of the indicator,   wherein the chemical compound is a powder,   wherein the change includes forming a color patch on the water-permeable material at least due to the chemical compound on contact with saliva,   wherein the color patch is observable at least on the second side of the sheet of water-permeable material, and   wherein the hydration level of the user depends on the identifier furthest away from the aperture that the color patch reaches after the disposable hydration sensing element is placed in the mouth of the user for a predetermined duration of time.   
     
     
         10 . A hydration sensor for measuring the hydration level of a user based on the user's saliva, the hydration sensor comprising:
 a digital timing device; and   a disposable sensing element including:
 a sheet of water-permeable material having a first side and a second side, with a chemical compound at least coupled to the first side; 
 a first sheet of water-impermeable material coupled to the first side of the water-permeable material; and 
 a second sheet of water-impermeable material coupled to the second side of water-permeable material, 
 wherein the hydration sensing element includes at least one aperture to allow saliva to reach the chemical compound from the at least one aperture, 
 wherein the chemical compound, at least due to contact with saliva, changes at least a portion of the water-permeable material, and the change is observable from at least a portion of one of the sheets of the water-impermeable material, 
 wherein at least a portion of the disposable sensing element is to be placed in the mouth of the user to measure the hydration level of the user, and 
 wherein the hydration sensor provides an indication regarding the hydration level of the user, based on time duration measured by the digital timing device, regarding the observable change of the water-permeable material, after the disposable hydration sensing element is placed in the mouth of the user. 
   
     
     
         11 . A hydration sensor as recited in  claim 10 , wherein the at least one aperture includes at least an edge of the water-permeable material that is exposed so that saliva is allowed to reach the chemical compound from the edge, or an opening on the first or the second sheet of water-impermeable material so that saliva is allowed to reach the chemical compound through the opening, if the disposable sensing element is placed in the mouth of the user. 
     
     
         12 . A hydration sensor as recited in  claim 10 , wherein at least the digital timing device of the sensor is in a carrier, which includes a mechanical device to attach the carrier to a piece of clothing worn by the user. 
     
     
         13 . A hydration sensor as recited in  claim 10  further comprising a plurality of other disposable sensing elements connected to the disposable sensing element to form a stack,
 wherein the plurality of other disposable sensing elements are similar to the disposable sensing element, and 
 wherein each of the elements of the stack is to be used individually for measuring hydration level. 
 
     
     
         14 . A hydration sensor as recited in  claim 10  further comprising another sensor to measure either another attribute of the user or an attribute of the environment where the user is in, wherein the indication regarding the hydration level of the user is also based on measurements from the another sensor. 
     
     
         15 . A hydration sensor as recited in  claim 10 , wherein the change includes forming a color patch on the water-permeable material at least due to the chemical compound on contact with saliva. 
     
     
         16 . A hydration sensor as recited in  claim 10 , wherein the indicator is on the second side of the sheet of water-permeable material. 
     
     
         17 . A hydration sensor as recited in  claim 16 ,
 wherein the indicator includes a plurality of identifiers, with each identifier spaced from the aperture by a different amount,   wherein the change includes forming a color patch on the water-permeable material at least due to the chemical compound on contact with saliva, and   wherein the hydration level of the user depends on the identifier furthest away from the aperture that the color patch reaches after the disposable hydration sensing element is placed in the mouth of the user for a predetermined duration of time, as measured by the digital timing device.   
     
     
         18 . A hydration sensor as recited in  claim 10 ,
 wherein the indicator includes a plurality of identifiers, with each identifier spaced from the aperture by a different amount, and   wherein the hydration level of the user depends on the identifier furthest away from the aperture that the changed portion of the water-permeable material extends to after the disposable sensing element is placed in the mouth of the user for a predetermined duration of time, as measured by the digital timing device.   
     
     
         19 . A hydration sensor as recited in  claim 10 ,
 wherein the indicator is on the second side of the sheet of water-permeable material,   wherein the chemical compound is a powder, and   wherein the second sheet of water-impermeable material is substantially transparent at least in the area of the indicator.   
     
     
         20 . A hydration sensor as recited in  claim 10 ,
 wherein the indicator is on the second side of the sheet of water-permeable material,   wherein the indicator includes a plurality of identifiers, with each identifier spaced from the aperture by a different amount,   wherein the second sheet of water-impermeable material is substantially transparent at least in the area of the indicator,   wherein the chemical compound is a powder,   wherein the change includes forming a color patch on the water-permeable material at least due to the chemical compound on contact with saliva,   wherein the color patch is observable at least on the second side of the sheet of water-permeable material, and   wherein the hydration level of the user depends on the identifier furthest away from the aperture that the color patch reaches after the disposable hydration sensing element is placed in the mouth of the user for a predetermined duration of time, as measured by the digital timing device.