Amperometric cholesterol biosensor

An amperometric cholesterol sensor comprising:

• a sensing electrode, the sensing electrode comprising;
• a non-conductive polymeric film, with the non-conductive polymeric film coated on one side with an electrically conductive formulation comprising a dispersion of electrically conductive graphite containing
• a first redox mediator,
• the first redox mediator selected from the group consisting of dimethyl ferrocene, 7,7,8,8-tetracyanoquinodimethane, tetrathiafulvalene, nickelocene, N-methylacridinium, tetrathiatetracene, N-methylphenazinium, and mixtures thereof, and
• a silver/silver chloride reference electrode comprising;
• a non-conductive polymeric film having an opening, the polymeric film coated on one side with an electrically conductive formulation comprising Ag/AgCl dispersed in a resin formulation, and
• a reagent strip, the reagent strip comprising;
• a water absorbent carrier, the carrier impregnated with a mixture comprising;
• a second redox mediator,
• the second redox mediator selected from the group consisting of 4-aminoantipyrine, 3,3',5,5'-tetramethylbenzidine, 2,2'-azino-di-›3-ethyl-benzthiazoline sulfonate!, o-dianisidine, o-toluidine, benzidine, CN.sup.-, Fe(CN).sub.6.sup.-4, I.sup.-, Co(NH.sub.3).sub.6.sup.++, Sn.sup.++, S.sup.-2, Tl.sup.+ and mixtures thereof, and a
• mixture of enzymes, the mixture of enzymes comprising;
• cholesterol esterase,
• cholesterol oxidase,
• horseradish peroxidase,
• and, at least one surfactant,
• and at least one stabilizer,
• with the reagent strip sandwiched between, and in simultaneous physical contact with, the coated side of the sensing electrode and the coated side of the reference electrode, with the reagent strip exposed through the opening in the reference electrode.

An amperometric sensing electrode, the sensing electrode comprising;

• a non-conductive support member,
• the non-conductive support member coated with an electrically conductive graphite formulation, the electrically conductive graphite formulation containing,
• a redox mediator,
• the redox mediator selected from the group consisting of dimethyl ferrocene, 7,7,8,8-tetracyanoquinodimethane, tetrathiafulvalene, nickelocene, N-methylacridinium, tetrathiatetracene, N-methylphenazinium, and mixtures thereof.