Capacitive sensing for drug delivery

Patent metadata

Field	Value
Publication number	US-2023398290-A1
Application number	US-202118034623-A
Country	US
Kind code	A1
Filing date	Mar 11, 2021
Priority date	Oct 30, 2020
Publication date	Dec 14, 2023
Grant date	—

Abstract

Processes for using a capacitive sensor to control drug delivery are described. The capacitive sensor measures a capacitance across a pair of electrodes arranged along either side of a container. The container includes an air chamber, a fluid chamber, and a stopper separating the air chamber from the fluid chamber. A volume of drug in the fluid chamber may be determined based on the measured capacitance. The volume is compared to a target volume, and if the volume in the fluid chamber is greater than the target volume, a stopper actuator expels a portion of the drug from the fluid chamber.

First claim

What is claimed is:

1 . A method for monitoring delivery of a drug, the method comprising:
measuring a capacitance across a pair of electrodes, the pair of electrodes arranged along either side of a container, the container comprising an air chamber, a fluid chamber, and a stopper separating the air chamber from the fluid chamber; determining, based on the measured capacitance, a volume of a drug in the fluid chamber; comparing the volume of the drug in the fluid chamber to a target volume; and in response to the volume of the drug in the fluid chamber being greater than the target volume, instructing a stopper actuator to expel at least a portion of the drug from the fluid chamber.

2 . The method of claim 1 , further comprising:
receiving a temperature measurement from a temperature sensor; and determining the volume of the drug in the fluid chamber based on the temperature measurement, wherein a relative permittivity of sensor dielectric depends on temperature.

3 . The method of claim 1 , further comprising:
receiving a humidity measurement from a humidity sensor; and determining the volume of the drug in the fluid chamber based on the humidity measurement, wherein a relative permittivity of sensor dielectric depends on humidity.

4 . The method of claim 1 , further comprising:
measuring a baseline volume of the drug in the fluid chamber prior to expelling the drug from the fluid chamber; and calculating the target volume based on the baseline volume.

5 . The method of claim 1 , wherein the measured capacitance is a first capacitance, the method further comprising:
after instructing the stopper actuator to expel the drug from the fluid chamber, measuring a second capacitance across the pair of electrodes; and in response to a difference between the first capacitance and the second capacitance being less than an error threshold, determining that a failure has occurred.

6 . The method of claim 5 , further comprising:
receiving at least one of a fluid chamber pressure from a pressure sensor and a stopper actuator power from a power sensor; and in response to at least one of the fluid chamber pressure exceeding a threshold pressure and the stopper actuator power exceeding a threshold power, determining that the failure is an occlusion.

7 . The method of claim 5 , further comprising:
receiving at least one of a fluid chamber pressure from a pressure sensor and a stopper actuator power from a power sensor; and in response to at least one of the fluid chamber pressure being lower than a threshold pressure and the stopper actuator power being lower than a threshold power, determining that the failure is a leakage.

8 . The method of claim 1 , further comprising:
prior to instructing the stopper actuator to expel the drug from the fluid chamber, performing a leakage detection procedure comprising: obtaining a first capacitance measurement; obtaining a second capacitance measurement a period of time after the first capacitance measurement; and comparing the first capacitance measurement to the second capacitance measurement to determine whether the second capacitance measurement is within a threshold tolerance of the first capacitance measurement.

9 . A method for delivering a drug comprising:
determining a target capacitance for a drug dose; measuring a capacitance across a pair of electrodes, the pair of electrodes arranged along either side of a container, the container comprising an air chamber, a fluid chamber, and a stopper separating the air chamber from the fluid chamber; comparing the measured capacitance to the target capacitance; and in response to the measured capacitance being greater than the target capacitance, instructing a stopper actuator to expel at least a portion of the drug from the fluid chamber.

10 . The method of claim 9 , further comprising:
receiving a temperature measurement from a temperature sensor; and determining the target capacitance for the drug dose based on the temperature measurement, wherein a relative permittivity of sensor dielectric depends on temperature.

11 . The method of claim 9 , further comprising:
receiving a humidity measurement from a humidity sensor; and determining the target capacitance for the drug dose based on the humidity measurement, wherein a relative permittivity sensor dielectric depends on humidity.

12 . The method of claim 9 , further comprising:
measuring a baseline capacitance prior to expelling the drug from the fluid chamber; and calculating the target capacitance based on the baseline capacitance.

13 . The method of claim 9 , wherein the measured capacitance is a first capacitance, the method further comprising:
after instructing the stopper actuator to expel the drug from the fluid chamber, measuring a second capacitance across the pair of electrodes; and in response to a difference between the first capacitance and the second capacitance being less than an error threshold, determining that a failure has occurred.

14 . The method of claim 13 , further comprising:
receiving at least one of a fluid chamber pressure from a pressure sensor and a stopper actuator power from a power sensor; and in response to at least one of the fluid chamber pressure exceeding a threshold pressure and the stopper actuator power exceeding a threshold power, determining that the failure is an occlusion.

15 . The method of claim 13 , further comprising:
receiving at least one of a fluid chamber pressure from a pressure sensor and a stopper actuator power from a power sensor; and in response to at least one of the fluid chamber pressure being lower than a threshold pressure and the stopper actuator power being lower than a threshold power, determining that the failure is a leakage.

16 . The method of claim 9 , further comprising:
prior to instructing the stopper actuator to expel the drug from the fluid chamber, performing a leakage detection procedure comprising: obtaining a first capacitance measurement; obtaining a second capacitance measurement a period of time after the first capacitance measurement; and comparing the first capacitance measurement to the second capacitance measurement to determine whether the second capacitance measurement is within a threshold tolerance of the first capacitance measurement.

17 . A method for characterizing a drug comprising:
measuring a capacitance across a pair of electrodes, the pair of electrodes arranged along either side of a container, the container containing a drug; determining an expected capacitance across the pair of electrodes, the expected capacitance based on an expected volume of the drug in the container and an expected relative permittivity of the drug; comparing the measured capacitance to the expected capacitance; and in response to the measured capacitance being outside a tolerance threshold of the expected capacitance, outputting an alert.

18 . The method of claim 17 , further comprising:
receiving a temperature measurement from a temperature sensor; and determining the expected capacitance based on the temperature measurement, wherein a relative permittivity of sensor dielectric depends on temperature.

19 . The method of claim 17 , the container further comprising an air chamber between the electrodes, the method further comprising:
receiving a humidity measurement from a humidity sensor; and determining the expected capacitance based on the humidity measurement, wherein a relative permittivity of sensor dielectric depends

Assignees

• Analog Devices Inc

Inventors

• Dugas Alan

Classifications

• A61M5/16813 Primary

  by controlling the degree of opening of the flow line · CPC title

• A61M5/1452

  pressurised by means of pistons · CPC title

• A61M5/16854

  by monitoring line pressure · CPC title

• A61M2205/3327

  Measuring · CPC title

• A61M2205/3379

  Masses, volumes, levels of fluids in reservoirs, flow rates · CPC title