Monitoring method and/or apparatus

Abstract

A method and apparatus for substance monitoring. One application is an easy to handle continuous glucose monitor using a group of hollow out-of-plane silicon microneedles to sample substances in interstitial fluid from the epidermal skin layer. The glucose of the interstitial fluid permeates a dialysis membrane and reaches a sensor. Using MEMS technology, for example, allows well-established batch fabrication at low cost.

1 . A method of in vivo monitoring of an individual's interstitial fluid comprising:
 creating a plurality of fluid paths through a stratum corneum area of the individual's skin, the fluid paths each comprising a distal end in fluid communication with interstitial fluid of the individual, a proximal end in analyte communication with a sensing area located outside of the patient's body, and an interior space extending between the distal and proximal ends of the fluid path;   allowing at least one analyte to passively diffuse from the patient's interstitial fluid through the fluid paths and into the sensing area; and   sensing a concentration of the at least one analyte in the sensing fluid using a sensor located at least partially in the sensing area.   
     
     
         2 . The method of  claim 1  wherein fluid in the fluid paths is not moving when the at least one analyte is passively diffusing there-through. 
     
     
         3 . The method of  claim 1  wherein there is no fluid movement between the distal ends of the fluid paths and the sensor when the at least one analyte is passively diffusing through the fluid paths and into the sensing area. 
     
     
         4 . The method of  claim 1  wherein no interstitial fluid is extracted from the individual during the diffusion and sensing steps. 
     
     
         5 . The method of  claim 1  further comprising displaying analyte concentration information remote from the stratum corneum area of the individual's skin. 
     
     
         6 . The method of  claim 5  further comprising wirelessly communicating analyte concentration information to a display. 
     
     
         7 . The method of  claim 1  wherein the sensing step is performed by a sensor in fluid communication with the sensing area and the interior spaces of the fluid paths, the method further comprising calibrating the sensor by moving sensing fluid into the sensing area. 
     
     
         8 . The method of  claim 7  further comprising moving sensing fluid out of the sensing area as sensing fluid is moved into the sensing area. 
     
     
         9 . The method of  claim 1  further comprising attaching a device comprising the sensor area and the sensor to the individual with adhesive. 
     
     
         10 . The method of  claim 1  further comprising providing a membrane located between the distal ends of the fluid paths and the sensor. 
     
     
         11 . The method of  claim 1  wherein creating the plurality of fluid paths through the stratum corneum area of the individual's skin comprises applying a microneedle array to the stratum corneum area. 
     
     
         12 . The method of  claim 1  wherein the proximal ends of the fluid paths are in fluid communication with the sensing area.