Microneedle arrays for biosensing and drug delivery

Abstract

Methods, structures, and systems are disclosed for biosensing and drug delivery techniques. In one aspect, a device for detecting an analyte and/or releasing a biochemical into a biological fluid can include an array of hollowed needles, in which each needle includes a protruded needle structure including an exterior wall forming a hollow interior and an opening at a terminal end of the protruded needle structure that exposes the hollow interior, and a probe inside the exterior wall to interact with one or more chemical or biological substances that come in contact with the probe via the opening to produce a probe sensing signal, and an array of wires that are coupled to probes of the array of hollowed needles, respectively, each wire being electrically conductive to transmit the probe sensing signal produced by a respective probe.

1 - 20 . (canceled) 
     
     
         21 . An analyte sensor for measuring an analyte in a biological fluid of a user, the analyte sensor comprising:
 a substrate comprising atop skin-facing surface, a bottom surface opposite the top surface, and a thickness therebetween;   an array of electrically-conductive probes, each electrically-conductive probe extending perpendicularly from the bottom surface of the substrate through the thickness of the substrate and past the top surface of the substrate;   an array of conductors, wherein each conductor is coupled to a corresponding electrically-conductive probe at the bottom surface of the substrate, and   wherein at least one electrically-conductive probe includes an electrode comprising a coating configured to interact with the analyte and produce an electrical sensing signal that transfers through the at least one electrically-conductive probe to a corresponding conductor.   
     
     
         22 . The analyte sensor of  claim 21 , wherein the analyte sensor is integrated into an adhesive patch for placement on skin. 
     
     
         23 . The analyte sensor of  claim 22 , wherein the adhesive patch is integrated with electronics configured for communication. 
     
     
         24 . The analyte sensor of  claim 21 , wherein the biological fluid is transdermal fluid, extracellular fluid, interstitial fluid, or blood. 
     
     
         25 . The analyte sensor of  claim 21 , wherein an electrochemical interaction between the analyte and electrode is detectable using amperometry, voltammetry, or potentiometry. 
     
     
         26 . The analyte sensor of  claim 21 , wherein a first electrically-conductive probe of the array is configured to detect a first analyte and a second electrically-conductive probe of the array is configured to detect a second, different analyte. 
     
     
         27 . The analyte sensor of  claim 21 , wherein the coating includes an entrapped biocatalyst. 
     
     
         28 . The analyte sensor of  claim 27 , wherein the biocatalyst is glucose oxidase. 
     
     
         29 . The analyte sensor of  claim 21 , wherein each of the electrically-conductive probes of the array is individually addressable. 
     
     
         30 . The analyte sensor of  claim 21 , wherein each conductor is configured to transmit the sensing signal produced by the respective electrically-conductive probe to a sensor circuit for processing. 
     
     
         31 . The analyte sensor of  claim 21 , wherein each of the electrically-conductive probes of the array is solid. 
     
     
         32 . The analyte sensor of  claim 21 , wherein each of the electrically-conductive probes of the array comprises silicon, glass, metal, or a resorbable polymer. 
     
     
         33 . The analyte sensor of  claim 21 , wherein the coating comprises a conducting polymer. 
     
     
         34 . The analyte sensor of  claim 21 , wherein the array of electrically-conductive probes includes at least one electrically-conductive probe comprising a counter electrode. 
     
     
         35 . The analyte sensor of  claim 21 , wherein the array of electrically-conductive probes includes a subset of electrically-conductive probes comprising a reference electrode. 
     
     
         36 . The analyte sensor of  claim 21 , wherein the analyte includes at least one selected from: a biochemical, a metabolite, an electrolyte, an ion, a pathogen, and a microorganism. 
     
     
         37 . The analyte sensor of  claim 21 , wherein the electrode comprises platinum. 
     
     
         38 . The analyte sensor of  claim 21 , wherein a periphery of the at least one electrically-conductive probe has a non-conductive material. 
     
     
         39 . The analyte sensor of  claim 21 , wherein the at least one electrically-conductive probe is insulated within the substrate. 
     
     
         40 . An analyte sensor for transdermally measuring an analyte in an interstitial fluid of a user, the analyte sensor comprising:
 a substrate comprising atop skin-facing surface, a bottom surface opposite the top surface, and a thickness therebetween;   an array of solid, electrically-conductive probes, each electrically-conducting probe extending perpendicularly from the bottom surface of the substrate through the thickness of the substrate and past the top surface of the substrate;   an array of conductors, wherein each conductor is coupled to a corresponding electrically-conductive probe at the bottom surface of the substrate, and   wherein at least one electrically-conductive probe includes a platinum electrode disposed on a surface of the at least one electrically-conductive probe, wherein the platinum electrode is configured to interact with the analyte and produce an electrical sensing signal that transfers through the at least one electrically-conductive probe to a corresponding conductor, and wherein the platinum electrode comprises a biocatalyst entrapped within a conducting polymer.   
     
     
         41 . The analyte sensor of  claim 40 , wherein the analyte sensor is integrated into an adhesive patch for placement on skin of the user. 
     
     
         42 . The analyte sensor of  claim 41 , wherein the adhesive patch is integrated with electronics configured for communication. 
     
     
         43 . The analyte sensor of  claim 40 , wherein the at least one electrically-conductive probe is insulated within the substrate. 
     
     
         44 . A method for measuring an analyte within a biological fluid comprising:
 providing an analyte sensor integrated with an adhesive patch, the analyte sensor comprising:
 a substrate comprising atop skin-facing surface, a bottom surface opposite the top surface, and a thickness therebetween; 
 an array of electrically-conductive probes, each electrically-conductive probe extending perpendicularly from the bottom surface of the substrate through the thickness of the substrate and past the top surface; 
 an array of conductors, wherein each conductor is coupled to a corresponding electrically-conductive probe at the bottom surface of the substrate, and 
 wherein at least one electrically-conductive probe includes an electrode comprising a coating configured to interact with the analyte and produce an electrical sensing signal that transfers through the at least one electrically-conductive probe to a corresponding conductor; 
   placing the adhesive patch on skin to transdermally contact the array of electrically-conductive probes of the analyte sensor with the biological fluid;   applying an electrical stimulus signal to the at least one electrically-conductive probe;   measuring a resultant sensing signal arising by an interaction between the coating on the electrode and the analyte in the biological fluid; and   determining a concentration of the analyte based on the sensing signal, wherein the sensing signal is transferred through the at least one electrically-conductive probe to the corresponding conductor.   
     
     
         45 . The method of  claim 44 , wherein the biological fluid is interstitial fluid. 
     
     
         46 . The method of  claim 45 , wherein the coating comprises a conducting polymer with an entrapped biocatalyst. 
     
     
         47 . The method of  claim 46 , wherein the at least one electrically-conductive probe is insulated within the substrate.