Multilayer enzyme electrode membrane

Claim 1

A method of making a contiguous multilayer membrane of about 40 to about 100 microns in overall thickness suitable for use with an electrochemical sensor in the measurement of an unknown which comprises: providing as a first layer, a polymer dissolved in an inert organic solvent and casting said polymer in solution onto an inert support surface which is unreactive with said polymer and does not form a bond to said polymer; permitting said solution to form a film and thereby obtaining a first relatively nonporous dense polymer layer of about 2 to about 5 microns in thickness; providing as a second layer, a composition comprising a polymer dissolved in an inert organic solvent, mixing said polymer dissolved in solvent with a nonsolvent for said polymer to obtain a dispersion and thereafter casting said dispersion onto said first layer and thereafter permitting said second layer to dry to form a porous polymer layer of about 2 to about 20 microns in thickness and less dense and more porous than the first layer; providing a third layer comprising an enzyme solution or suspension and depositing said third layer onto the exposed surface of the second layer; providing as a fourth layer, a composition comprising a polymer dissolved in an inert organic solvent, mixing said polymer dissolved in solvent with a nonsolvent for said polymer to obtain a dispersion and thereafter casing said dispersion onto the exposed surface of the third layer to provide a fourth porous polymer layer of about 2 to about 20 microns in thickness and less dense and more porous than the first layer; and thereby forming said contiguous multilayer membrane.

Claim 2

A method of making a contiguous multilayer membrane of about 40 to about 100 microns in overall thickness suitable for use with an electrochemical sensor in the measurement of an unknown which comprises: providing as a first layer, a polymer dissolved in an inert organic solvent and casting said polymer in solution onto an inert support surface which is unreactive with said polymer and does not form a bond to said polymer; permitting said solution to form a film and thereby obtaining a first relatively nonporous dense polymer layer of about 2 to about 5 microns in thickness; providing as a second layer, a composition comprising a polymer dissolved in an inert organic solvent, mixing said polymer dissolved in solvent with a nonsolvent for said polymer to obtain a dispersion and thereafter casting said dispersion onto said first layer and thereafter permitting said second layer to dry to form a porous polymer layer of about 2 to about 20 microns in thickness and less dense and more porous than the first layer; providing a third layer comprising an enzyme solution or suspension and depositing said third layer onto the exposed surface of the second layer; providing as a fourth layer, a composition comprising a polymer dissolved in an inert organic solvent, mixing said polymer dissolved in solvent with a nonsolvent for said polymer to obtain a dispersion and thereafter casing said dispersion onto the exposed surface of the third layer to provide a fourth porous polymer layer of about 2 to about 20 microns in thickness and less dense and more porous than the first layer; and thereby forming said contiguous multilayer membrane.

Claim 10

A method of making a contiguous multilayer membrane of about 40 to about 100 microns in overall thickness suitable for use with an electrochemical sensor in the measurement of an unknown which comprises: (a) providing a first cellulose acetate polymer dissolved in an inert organic solvent; (b) casting said first polymer in solution onto an inert support surface which in unreactive with said cellulose acetate and does not form a bond to said cellulose acetate; (c) permitting said first polymer in solution to form a film and thereby obtain a first relatively nonporous dense layer of cellulose acetate of about 2 to about 5 microns in thickness; (d) providing a second cellulose acetate polymer dissolved in an inert organic solvent mixing said second polymer with a nonsolvent for said polymer to form a dispersion thereof; (e) casting said second cellulose acetate polymer dispersion onto said first layer of cellulose acetate and permitting said cellulose acetate polymer to form a porous second cellulose acetate layer of about 2 to about 20 microns in thickness and less dense and more porous than the first layer; (f) providing an aqueous solution or suspension of an enzyme and depositing said enzyme in a layer onto the surface of said second polymer; and (g) repeating (d), (e) and (f) at least once to deposit at least one additional said second cellulose acetate layer and at least one additional enzyme layer; thereby forming said contiguous multilayer cellulose acetate polymer membrane.

Claim 11

A method of making a contiguous multilayer membrane of about 40 to about 100 microns in overall thickness suitable for use with an electrochemical sensor in the measurement of an unknown which comprises: (a) providing a first cellulose acetate polymer dissolved in an inert organic solvent; (b) casting said first polymer in solution onto an inert support surface which in unreactive with said cellulose acetate and does not form a bond to said cellulose acetate; (c) permitting said first polymer in solution to form a film and thereby obtain a first relatively nonporous dense layer of cellulose acetate of about 2 to about 5 microns in thickness; (d) providing a second cellulose acetate polymer dissolved in an inert organic solvent mixing said second polymer with a nonsolvent for said polymer to form a dispersion thereof; (e) casting said second cellulose acetate polymer dispersion onto said first layer of cellulose acetate and permitting said cellulose acetate polymer to form a porous second cellulose acetate layer of about 2 to about 20 microns in thickness and less dense and more porous than the first layer; (f) providing an aqueous solution or suspension of an enzyme and depositing said enzyme in a layer onto the surface of said second polymer; and (g) repeating (d), (e) and (f) at least once to deposit at least one additional said second cellulose acetate layer and at least one additional enzyme layer; thereby forming said contiguous multilayer cellulose acetate polymer membrane.