Temperature-compensated in-vivo sensor
A reagent matrix composition disposed on an electrically conductive electrode to form an in-vivo sensor for a predefined analyte includes a first hydrogel layer containing an enzyme that is a substrate for the analyte adjacent the electrically conductive electrode and a composite membrane layer disposed onto the first hydrogel layer where the composite layer includes a membrane hydrogel containing a plurality of microspheres. The plurality of microspheres is made of a material having no or little permeability to the analyte and a substantially high permeability to oxygen.
1 . An in-vivo sensor for measuring an analyte, the sensor comprising:
a base insulating layer;
an electrically conductive electrode disposed on the base insulating layer;
a semi-permeable layer disposed over the electrode;
a first hydrogel layer containing an enzyme that is a substrate for the analyte disposed on the semi-permeable layer;
a composite membrane layer disposed on the first hydrogel layer wherein the composite layer includes a hydrogel containing a plurality of microspheres, the plurality of microspheres being made of a material having no or little permeability to the analyte and substantially high permeability to oxygen.
2 . The sensor of claim 1 further comprising a second hydrogel layer disposed over the composite membrane layer.
3 . The sensor of claim 2 wherein the second hydrogel layer further includes a catalase.
4 . The sensor of claim 1 wherein the material of the microspheres is polydimethylsiloxane.
5 . The sensor of claim 1 wherein the first hydrogel layer is one of a polyurethane or a poly-2-hydroxyethyl methylacrylate.
6 . The sensor of claim 2 wherein the second hydrogel layer is one of polyurethane or poly-2-hydroxyethyl methacrylate.
7 . The sensor of claim 1 wherein the composite membrane layer has a ratio of the quantity of microspheres to the quantity of membrane hydrogel selected for a predefined dynamic measurement range of the analyte.
8 . A reagent matrix composition disposed on an electrically conductive electrode to form an in-vivo sensor for a predefined analyte, the composition comprising:
a first hydrogel layer containing an enzyme that is a substrate for the analyte adjacent the electrically conductive electrode; and
a composite membrane layer disposed onto the first hydrogel layer wherein the composite layer includes a membrane hydrogel containing a plurality of microspheres, the plurality of microspheres being made of a material having no or little permeability to the analyte and a substantially high permeability to oxygen.
9 . The composition of claim 8 further comprising a semi-permeable layer between the first hydrogel layer and the electrically conductive electrode.
10 . The composition of claim 8 further comprising a second hydrogel layer disposed onto the composite membrane layer.
11 . The composition of claim 10 wherein the second hydrogel layer contains a catalase.
12 . The composition of claim 8 wherein the first hydrogel layer, the membrane hydrogel and the second hydrogel layer are one of polyurethane or poly-2-hydroxyethyl methacrylate.
13 . The composition of claim 8 wherein the material of the microspheres is polydimethylsiloxane.
14 . The composition of claim 8 wherein the composite membrane layer has a ratio of the quantity of microspheres to the quantity of membrane hydrogel selected for a predefined dynamic measurement range of the analyte.
15 . A method of making a sensor for in-vivo measurement of an analyte, the method comprising:
obtaining an electrically conductive electrode;
disposing a first hydrogel layer containing an enzyme onto the electrically conductive electrode; and
disposing a composite membrane layer onto the first hydrogel layer wherein the composite membrane layer includes a membrane hydrogel containing a plurality of microspheres, the plurality of microspheres being made of a material having no or little permeability to the analyte and a substantially high permeability to oxygen.
16 . The method of claim 15 further comprising disposing a semi-permeable layer between the first hydrogel layer and the electrically conductive electrode.
17 . The method of claim 15 further comprising disposing a second hydrogel layer onto the composite membrane layer.
18 . The method of claim 15 further comprising formulating the first hydrogel layer and the membrane hydrogel from polyurethane or poly-2-hydroxyethyl methacrylate.
19 . The method of claim 15 further comprising formulating the microspheres from polydimethylsiloxane.
20 . The method of claim 17 further comprising formulating the second hydrogel layer from polyurethane or poly-2-hydroxyethyl methacrylate.
21 . The method of claim 17 further comprising formulating the second hydrogel layer containing a catalase.