Ph meter

Abstract

Voltammetric sensors prepared from composite materials and optionally using microfabrication techniques enable detection of analyte in sample volumes under ten microliters.

1 . A device for measuring the concentration of an analyte in microliter-scale liquid samples in which the sample is held by surface tension between two anvils, each comprising a containment area where the sample is deposited (or contacted), wherein one or both anvils have embedded in them one or more electrodes of the analyte sensor in conductive contact with a surface of the anvil having a containment area wetted by the sample. 
     
     
         2 . The device of  claim 1 , wherein the containment area is defined by a coating that facilitates adhesion of the sample to the surface of the anvil. 
     
     
         3 . The device of  claim 2 , in which one or more electrodes of the sensor is fabricated by printing the electrode components on a polymeric membrane or glass. 
     
     
         4 . The device of  claim 3 , wherein the device enables multi-channel analyte concentration measurements on a plurality of small sample volumes, each held by surface tension between two anvil surfaces that form a sensor, wherein a single voltammetric scan is performed across an array of such sensors. 
     
     
         5 . The device of  claim 4 , wherein the device comprises: means for containing a plurality of microliter samples by surface tension between opposing, proximal-ends of a plurality of sets of anvils, wherein each set of anvils provides a functional sensor, said anvils optionally in a substantially parallel, spaced-apart relationship; means for supplying current to the anvils; means for holding the anvils in an array; means for performing voltammetric scanning of the sensors; and means connected to the sensors for accepting signals transmitted through them and making analyte concentration measurements thereon, wherein analyte concentration measurements are made at more than one sensors simultaneously using the more than one sensors and more than one means for accepting signals and making analyte concentration measurements thereon. 
     
     
         6 . The device of  claim 5 , wherein the device comprises: a first anvil and a second anvil that together form the analyte sensor, wherein said anvils are mechanically coupled to one another by a means that enables adjustment of the separation between the anvils such that a liquid sample placed on a surface of one of said anvils can be contacted with a surface the other anvil, thereby placing the two anvils in conductive contact, and retained in such position for a sufficient period of time for an analyte measurement to be made using voltammetric scanning. 
     
     
         7 . The device of  claim 6 , wherein the device comprises a working electrode comprising a polymeric material comprising a redox active material. 
     
     
         8 . The device of  claim 7 , wherein the polymeric material is composed of polyvinyl alcohol and silica. 
     
     
         9 . The device of  claim 8 , wherein the device comprises a reference electrode having a reference junction composed of a composite formed from an ionic liquid, a conductive material, and a polymer. 
     
     
         10 . The device of  claim 9 , wherein each of the plurality of small sample volumes comprises an individual volume of ten or fewer microliters.