Membrane apparatus

Claim 2

Apparatus employing a semi-permeable membrane wherein the membrane is supported against a surface and wherein the likelihood of damage to such membrane during mounting and use is minimized comprising in combination a first member formed with a recess having a cylindrical sidewall and a bottom having a convex surface, a membrane, an annular gasket, a second member having a concave end surface and clamping means, said second member fitting within said gasket and positioning said membrane against said first member wherein said membrane is stretched over said convex surface of said first member by the complemental concave end surface of said second member to effect close contact between said membrane and said convex surface, said annular gasket in an unstressed condition loosely fitting within said cylindrical sidewall of said recess of said first member, any fluid located between said membrane and said convex surface of said first membrane being forced outward by said membrane stretching and being allowed to pass through the space formed by the loose fitting relationship between said annular gasket and said cylindrical sidewall of said first member, said clamping means applying compressive force to said annular gasket and to said second member to form a fluid-tight seal between said cylindrical sidewall of said first member and said second member through said annular gasket and to hold said membrane in stretched relationship against and in close contact with said first member.

Claim 3

A glucose sensing apparatus comprising in combination a hydrogen peroxide detecting polarographic assembly having a recess with a convex bottom surface portion and a surrounding cylindrical sidewall, said assembly comprising an anode having a circular end surface and a cathode having an annular end surface in spaced surrounding relation to said anode surface, each of said end surfaces forming part of said convex surface portion of said assembly; a semi-permeable membrane containing glucose oxidase overlying and in close contact with said convex surface; a generally cylindrical electrically conductive flow chamber member having a concave end surface portion formed with flow passage means therein and having inlet and outlet means communicating with said flow passage means, said concave end surface being complemental to and aligned with said convex surface of said polarographic assembly and in overlaying contact with the portion of said membrane in contact with said convex surface, said flow passage means and said membrane forming a flow-through sample chamber providing a sample flow pattern wherein a sample flowing therethrough flows in a straight line over a small portion of said cathode surface, diametrically across said anode surface and thence circumferentially over a substantial portion of said cathode surface before exiting from said sample chamber; an O-ring type sealing means surrounding said flow chamber member and in an unstressed condition loosely fitting within said cylindrical sidewall of said polarographic assembly and in contact with the adjacent upper surface portion of said membrane; an inverted generally cup-shaped sealing member disposed coaxially over said flow-chamber member and having an annular surface engaging said O-ring; means for clamping said sealing member to said polarographic assembly in a manner to effect compression of said O-ring and sealing contact thereof with said chamber member, said cylindrical sidewall of said polarographic assembly and said membrane; compression spring means disposed between said sealing member and said chamber member for biasing the latter axially toward said membrane; and means for effecting an electrical connection between said cathode and said flow chamber member.

Claim 4

A glucose sensing apparatus comprising in combination a hydrogen peroxide detecting polarographic assembly having a recess with a convex bottom surface portion and a surrounding cylindrical sidewall, said assembly comprising an anode having a circular end surface and a cathode having an annular end surface in spaced surrounding relation to said anode surface, each of said end surfaces forming part of said convex surface portion of said assembly; a semi-permeable membrane containing glucose oxidase overlying and in close contact with said convex surface; a generally cylindrical electrically conductive flow chamber member having a concave end surface portion formed with flow passage means therein and having inlet and outlet means communicating with said flow passage means, said concave end surface being complemental to and aligned with said convex surface of said polarographic assembly and in overlaying contact with the portion of said membrane in contact with said convex surface, said flow passage means and said membrane forming a flow-through sample chamber providing a sample flow pattern wherein a sample flowing therethrough flows in a straight line over a small portion of said cathode surface, diametrically across said anode surface and thence circumferentially over a substantial portion of said cathode surface before exiting from said sample chamber; an O-ring type sealing means surrounding said flow chamber member and in an unstressed condition loosely fitting within said cylindrical sidewall of said polarographic assembly and in contact with the adjacent upper surface portion of said membrane; an inverted generally cup-shaped sealing member disposed coaxially over said flow-chamber member and having an annular surface engaging said O-ring; means for clamping said sealing member to said polarographic assembly in a manner to effect compression of said O-ring and sealing contact thereof with said chamber member, said cylindrical sidewall of said polarographic assembly and said membrane; compression spring means disposed between said sealing member and said chamber member for biasing the latter axially toward said membrane; and means for effecting an electrical connection between said cathode and said flow chamber member.

Claim 5

Apparatus according to claim 2 wherein said cathode and said flow chamber member are formed of the same electrically conductive material.