	US 12,257,045 B2
	Tracking insertion and removal times of a continuous glucose monitoring sensor
Anthony P. Russo, New York, NY (US)
Assigned to Ascensia Diabetes Care Holdings AG, Basel (CH)
Filed by Ascensia Diabetes Care Holdings AG, Basel (CH)
Filed on Jul. 13, 2021, as Appl. No. 17/374,897.
Claims priority of provisional application 63/051,853, filed on Jul. 14, 2020.
Prior Publication US 2022/0015671 A1, Jan. 20, 2022
Int. Cl. A61B 5/145 (2006.01); A61B 5/00 (2006.01)

CPC A61B 5/14532 (2013.01) [A61B 5/0015 (2013.01); A61B 5/14503 (2013.01); A61B 5/6848 (2013.01)]

24 Claims

1. A continuous glucose monitoring (CGM) system, comprising:

a sensor unit, comprising:

a sensor unit memory having an identifier stored therein; and

an analyte sensor configured to be inserted into a subcutaneous region of a user for continuously monitoring a glucose concentration level of the user;

an analog front end configured to apply a bias voltage to the analyte sensor and to measure a resultant current;

a switch in communication with the sensor unit and configured to detect when the analyte sensor has been removed from a skin surface of the user;

a second memory configured to store therein a plurality of sensor identifiers;

a real-time clock; and

at least one processor in communication with the second memory, the real-time clock, and the sensor unit, wherein the at least one processor is configured to execute computer instructions to:

read the identifier stored in the sensor unit memory;

determine whether the identifier matches any previously-stored identifier in the second memory;

store the identifier and a skin insertion time stamp in the second memory in response to the identifier not matching any previously-stored identifier in the second memory, the real-time clock used to generate the skin insertion time stamp;

receive, from the analog front end, the resultant current;

determine the glucose concentration level based on the resultant current;

in response to detecting, via the switch, the analyte sensor being removed from the skin surface, store a skin removal time stamp generated by the real-time clock in the second memory;

in response to detecting, via the switch, the analyte sensor being reinserted into the skin surface and the identifier matching the identifier stored in the second memory, obtain a skin reinsertion time stamp of the analyte sensor using the real-time clock;

determine an elapsed removal time of the analyte sensor based on the skin removal time stamp and the skin reinsertion time stamp;

responsive to receiving an additional signal from the analyte sensor, determine whether the analyte sensor has exceeded a predetermined maximum removal time limit based on the elapsed removal time; and

responsive to determining the analyte sensor has exceeded the predetermined maximum removal time limit, preventing continued use of the analyte sensor by preventing processing of any new signals from the analyte sensor.