Devices, systems, and methods for measuring analytes in interstitial fluid

Inventors

Gofman, Igor Y.

Assignees

Ascensia Diabetes Care Holdings AG

Abstract

An analyte monitor includes a controller including a processor coupled to a memory. The memory has instructions stored therein that, when executed by the processor, cause the controller to: provide a working electrode voltage to a working electrode of an analyte sensor; selectively provide a first counter electrode voltage and a second counter electrode voltage to a counter electrode of the analyte sensor; and provide a guard ring voltage to a guard ring associated with the working electrode. The analyte monitor further includes a current measurement circuit coupled to the controller and configured to measure current flow to the working electrode and a reference resistor electrically coupled between the working electrode and the guard ring associated with the working electrode. Other monitors, systems, sensors, and methods are disclosed.

Core Innovation

The invention relates to an analyte monitor and an analyte monitoring system for interstitial fluid analyte monitoring. A transmitter/controller applies a working electrode voltage to a working electrode and one or more counter electrode voltages to a counter electrode, and a guard ring voltage source provides a guard ring voltage to a guard ring that at least partially surrounds a contact region of the working electrode.

The working electrode voltage source, the counter electrode voltage source, and the guard ring voltage source are separate and distinct voltage sources. A current measurement circuit measures current flow from the working electrode voltage source to the working electrode, and the controller determines that the analyte monitor is faulty based on the current flow. The integrity check includes providing first, second, and third instructions to the working electrode voltage source, the counter electrode voltage source, and the guard ring voltage source, respectively.

A reference resistor electrically couples between the working electrode and the guard ring, and the integrity check uses expected current flow behavior based on voltage relationships among the working electrode, counter electrode, and guard ring. In one configuration the controller sets electrode, guard ring, and counter voltages to be equal to expect no or minimal current, and in another configuration the controller sets the guard ring voltage differently so that current is expected to flow through the reference resistor and match an expected value derived from a voltage difference divided by the resistance of the reference resistor. Fault indication is performed when measured current flow exceeds or falls outside predetermined amperage thresholds.

Claims Coverage

The independent claims cover three inventive features: separate working electrode, counter electrode, and guard ring voltage sources; current-based integrity checking with fault determination; and an analyte monitor or system that uses a reference resistor coupled between the working electrode and the guard ring.

The core inventive coverage centers on separate voltage sources for the working electrode, counter electrode, and guard ring; measuring current flow to the working electrode; and determining faulty status based on an integrity check that applies specific voltage relationships while using a reference resistor coupled between the working electrode and the guard ring.

Stated Advantages

Documented Applications

No documented applications found