Devices capable of fluid sample concentration for extended sensing of analytes

Abstract

The disclosed invention provides a sensing device capable of concentrating a fluid sample with respect to a target analyte and a reference analyte, and measuring the target analyte and reference analyte in the concentrated sample. The invention includes a concentrator that may include a selectively permeable membrane, or a gel having an increasing density gradient. In another embodiment, the invention includes an air or gas gap between a fluid transport channel and the concentrator. In another embodiment, the sensing device includes a driver for electronically moving a fluid sample through the channel and membrane to cause concentration. In some embodiments, the invention may also determine the change in molarity of the fluid sample with respect to the target analyte, as the sample is concentrated by the device.

What is claimed is: 
     
         1 . A sensing device, comprising:
 an analyte sensor for measuring a concentration of a target analyte in a fluid sample;   a reference sensor for measuring a concentration of a reference analyte in the fluid sample;   a channel configured to convey the fluid sample to the analyte sensor and the reference sensor; and   a concentrator in fluidic communication with the channel, the concentrator configured to concentrate the fluid sample with respect to the target analyte to increase a first molarity of the target analyte to a second molarity, and wherein the concentrator is configured to concentrate the fluid sample with respect to the reference analyte to increase a third molarity of the reference analyte to a fourth molarity.   
     
     
         2 . The sensing device of  claim 2 , wherein a ratio of the first molarity to the second molarity is substantially equal to a ratio of the third molarity to the fourth molarity. 
     
     
         3 . The sensing device of  claim 1 , wherein the concentrator further comprises:
 a membrane in fluidic communication with the fluid sample, the membrane having a selective permeability that allows passage of fluid and prevents passage of the target analyte and the reference analyte.   
     
     
         4 . The sensing device of  claim 3 , wherein the concentrator further comprises:
 a pump in fluidic communication with the membrane, the pump configured to draw water and solutes through the membrane and out of the channel to concentrate the fluid sample relative to the target analyte and the reference analyte.   
     
     
         5 . The sensing device of  claim 1 , further comprising:
 a plurality of analyte sensors, wherein a first subset of the plurality of analyte sensors is configured to measure a concentration of the target analyte at the first molarity, and a second subset of the plurality of analyte sensors is configured to measure a concentration of the target analyte at the second molarity.   
     
     
         6 . The sensing device of  claim 1 , further comprising:
 a flow sensor for measuring at least one of the following: a rate of flow of the fluid sample into the channel, and a rate of flow of the fluid sample through the channel.   
     
     
         7 . The sensing device of  claim 1 , further comprising:
 an osmolality sensor configured to measure a total osmolality of the fluid sample.   
     
     
         8 . The sensing device of  claim 4 , further comprising:
 a draw material in fluidic communication with the membrane; and   an osmolality sensor configured to measure a total osmolality of the draw material.   
     
     
         9 . The sensing device of  claim 1 , wherein the concentrator further comprises:
 a gel having a density gradient configured to increase in a direction of fluid sample flow through the channel.   
     
     
         10 . The sensing device of  claim 1 , wherein the concentrator further comprises:
 a gel having a plurality of sections, wherein each of the plurality of section has a density, and wherein the plurality of sections is arranged so that the density increases in a direction of fluid sample flow through the channel.   
     
     
         11 . The sensing device of  claim 1 , wherein the concentrator further comprises:
 a material having a plurality of pores configured to interact with the target analyte as the sample fluid sample flows through the channel.   
     
     
         12 . The sensing device of  claim 1 , further comprising:
 a sweat stimulator, comprising an agent for causing sweating, and a pair of electrodes configured to drive the agent into skin by iontophoresis.   
     
     
         13 . A sensing device, comprising:
 an analyte sensor for measuring a concentration of a target analyte in a fluid sample;   a channel configured to convey the fluid sample to the analyte sensor;   a concentrator comprising a membrane in fluidic communication with a pump, wherein the concentrator is configured to concentrate the fluid sample with respect to the target analyte;   a gap separating the channel from the concentrator, the gap comprising one of: air, or a gas; and   a protective covering comprising a vapor impermeable film.   
     
     
         14 . A sensing device, comprising:
 an analyte sensor for measuring a concentration of a target analyte in a fluid sample;   a channel configured to convey the fluid sample to the analyte sensor;   a concentrator comprising a membrane in fluidic communication with the channel, wherein the concentrator is configured to concentrate the fluid sample with respect to the target analyte; and   a driver for moving the fluid sample through the membrane, the driver comprising one of the following: a first electrode located on an upstream side of the membrane and a second electrode located on a downstream side of the electrode; and a pump configured to push the fluid sample through the membrane.   
     
     
         15 . The device of  claim 14 , further comprising:
 a reference sensor for measuring a concentration of a reference analyte in the fluid sample, wherein the channel is configured to convey the fluid sample to the analyte sensor and the reference sensor, wherein the concentrator is configured to concentrate the fluid sample with respect to the target analyte and the reference analyte.