Noninvasive blood glucose measuring device

• US 5,140,985 A
• Filed: 10/21/1991
• Issued: 08/25/1992
• Est. Priority Date: 12/11/1989
• Status: Expired due to Fees

• Current Assignee: Jon M. Schroeder, Joseph F. Long
• Original Assignee: Jon M. Schroeder, Joseph F. Long
• Inventors: Long, Joseph F., Schroeder, Jon M.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): NASSER, ROBERT L
• Application Number:
  US07/781,485
• Time in Patent Office: 309 Days
• Field of Search: 128/632, 128/635, 128/637
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14521 using means for promoting sweat production, e.g. heating the skin measuring sweat secretion A61B5/4266
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase

Abstract

This invention gives an indication of blood glucose by measuring the glucose content in sweat. Other bodily fluids such as saliva, urine, or tears could also be used. The measuring system in our unit includes the substrate which may have printed wiring thereon; a plurality of oxygen sensors for measuring oxygen remaining after oxidation of the glucose with glucose oxidase and a reference oxygen sensor, all covered by a semi-porous membrane; a wick for conveying sweat to the glucose sensors and beyond; a battery, and a plurality of electroplateable indicator bars for indicating the glucose concentration in the sweat by difference in electrical output between the reference oxygen sensor and oxygen sensors that measure oxygen after reaction with the glucose oxidase or glucose sensors; a calibrateable legend associated with the bars relates the plating to the glucose level in the blood. In a second embodiment a liquid crystal display replaces the electroplateable indicator bars. This assembly allows the measurement of glucose level as related to glucose found in sweat by directly attaching the device to the arm and priming or activating the device with an electrolyte after which the measuring device will react with localized sweating and indicate the wearer'"'"'s blood glucose level for at least an 18 hour period. The sealed monolithic unit becomes the entire measuring instrument and indicating device.

Claims

1. A non-invasive glucose monitoring unit comprising:

a. a housing means;

b. a replaceable strip means with a sealing ring to seal against a persons skin in said housing means;

c. an oxygen reference cell and multiple glucose sensing units on said replaceable strip means;

d. a wick means in said housing means whereby clean perspiration is picked up from skin by said wick means and transported past said oxygen reference cell and past said multiple glucose sensing units both of which are integrally formed on said replaceable strip means;

e. a glucose oxidizing enzyme contained in each of said multiple glucose sensing units;

f. an oxygen measuring cell in each of said multiple glucose sensing units;

g. an electronic circuitry means formed on said replaceable strip means in said housing means to measure and indicate difference in oxygen in each of said multiple glucose sensing units compared with oxygen present in said oxygen reference cell;

h. a battery means in said housing means to power said electronic circuitry means.

2. A non-invasive glucose monitoring unit as in claim 1 wherein said electronic circuitry means comprises a group of electrodes each immersed in a plateable solution with each one of said group of electrodes connected with circuitry to compare the difference in electrical output between said oxygen reference cell and said oxygen measuring cell in each of said glucose sensing units;

said electronic circuitry means having a different sized resistor cooperating with each of said oxygen measuring cells thereby plating a different one of said electrodes for different levels of said electrical output between said oxygen reference cell and one of said oxygen measuring cells.

3. A non-invasive glucose monitoring unit as in claim 2 wherein said group of electrodes each comprises a carbon electrode in a stannous chloride electrolyte with the silver color of the plated carbon electrode being the indicating means whereby the difference in output between said oxygen reference cell and each of said oxygen measuring cells in said multiple glucose sensing units are visually indicated.

4. A non-invasive glucose monitoring unit as in claim 1 wherein said battery means is a chemical battery formed on said replaceable strip.

5. A non-invasive glucose monitoring unit as in claim 1 wherein said wick means is a wick that leads from under said replaceable strip means, through said replaceable strip means and over said oxygen reference cell and said multiple glucose sensing units and out through said housing means for evaporation of said perspiration.

6. A non-invasive glucose monitoring unit as in claim 5 wherein said housing means has a insulating portion and an interclasping fastener to hold said replaceable strip means close to an individual'"'"'s skin thereby promoting formation of perspiration and minimizing ambient oxygen diffusion to perspiration in said wick.

7. A non-invasive glucose monitoring unit comprising:

a. a housing means with flexible means to hold said housing means in contact with skin;

b. a battery in said housing means;

c. a replaceable strip means and a sealing ring means for said replaceable strip means in said housing;

d. an oxygen reference cell and a glucose sensing unit, said glucose sensing unit comprising an oxygen measuring cell and a glucose oxidizing enzyme;

e. a wick means in said housing means whereby clean perspiration may be picked up from the skin and hermetically transported past said oxygen reference cell and means whereby a portion of said clean perspiration may be hermetically transported past said glucose sensing unit with means for contacting said portion of said clean perspiration with said glucose oxidizing enzyme in said glucose sensing unit;

f. a Wheatstone Bridge circuit means in said housing means and powered by said battery in said housing means wherein an output from said oxygen measuring cell in said glucose sensing unit is compared with said oxygen reference cell with a position of a variable resistor used to zero a null point ammeter indicating glucose concentration in said clean perspiration.

8. A non-invasive glucose monitoring unit comprising:

a. a housing means;

b. a replaceable strip means contained in said housing means;

c. a sealing ring on said replaceable strip means allowing said housing means to seal said replaceable strip means to a person'"'"'s skin;

d. an oxygen reference cell and multiple glucose sensing units formed on said replaceable strip means;

e. a wick means to collect and hermetically transport perspiration to contact said oxygen reference cell and said multiple glucose sensing units;

said wick means extending through said housing means allowing evaporation and capillary action to cause said perspiration transport;

f. an oxygen measuring cell, an oxygen permeable membrane and fixed glucose oxidase comprising each of said multiple glucose sensing units;

g. a battery means in said housing means;

h. an indicator means visible through said housing means and electronic circuitry means powered by said battery means and cooperating with said oxygen reference cell, said multiple glucose sensing units, and said indicator means to indicate glucose concentration by difference in output between said oxygen reference cell and said multiple glucose sensing units.

9. A non-invasive glucose monitoring unit as in claim 8 wherein said indicator means is a liquid crystal display unit.

10. A non-invasive glucose monitoring unit comprising:

a. an insulating band means with means to fasten said insulating band means close to a persons body;

b. a replaceable strip fitting under said insulating band means;

c. a chemical battery, an oxygen reference cell and multiple glucose sensing units formed on said replaceable strip;

d. a wick means cooperating with said replaceable strip in said insulating band means to collect perspiration formed under said replaceable strip and to transport said perspiration past said oxygen reference cell and past said multiple glucose sensing units;

said multiple glucose sensing units each comprising an oxygen measuring cell, an oxygen permeable membrane and fixed glucose oxidase membrane;

e. a group of carbon electrodes each immersed in a plateable solution with each one of said group of electrodes connected with circuitry to compare the difference in electrical output between said oxygen reference cell and said oxygen measuring cells in each of said glucose sensing units by plating individual ones of said group of carbon electrodes;

said group of carbon electrodes and said circuitry being formed on said replaceable strip.