Polycarbonate urea/urethane polymers for use with analyte sensors

A method of making an analyte sensor for implantation within a mammal comprising the steps of:

• providing a base layer;
• forming a conductive layer on the base layer, wherein the conductive layer includes a working electrode;
• forming an analyte sensing layer on the conductive layer, wherein the analyte sensing layer includes an oxidoreductase;
• forming an analyte modulating layer on the analyte sensing layer, wherein:
• the analyte modulating layer comprises a polyurea-urethane copolymer formed from a reaction mixture comprising:
• (a) a diisocyanate;
• (b) a hydrophilic polymer comprising a hydrophilic diol or hydrophilic diamine;
• (c) a siloxane having an amino, hydroxyl or carboxylic acid functional group at a terminus;
• and
• (d) a polycarbonate diol, wherein:
• the diisocyanate comprises a hexamethylene diisocyanate and/or a methylene diphenyl diisocyanate;
• the hydrophilic polymer comprising a hydrophilic diol or hydrophilic diamine comprises a polyetheramine;
• the siloxane having an amino, hydroxyl or carboxylic acid functional group at a terminus comprises a polydimethylsiloxane;
• and
• the polycarbonate diol comprises a poly(1,6-hexyl carbonate) diol and/or a poly(1,6 hexyl-1,5 pentyl carbonate) diol;
• and
• the diisocyanate comprises:
• from 17% to 23% weight percent hexamethylene diisocyanate;
• and
• from 0% to 8.5% weight percent methylene diphenyl diisocyanate;
• and
• the polydimethylsiloxane comprises from 14% to 32% weight percent polydimethylsiloxane-A15;
• and
• the polycarbonate diol comprises from 7.5% to 19% weight percent poly(1,6-hexyl carbonate) diol.