Plate capacitor for dosage sensing

Patent metadata

Field	Value
Publication number	US-11229749-B2
Application number	US-201916559337-A
Country	US
Kind code	B2
Filing date	Sep 3, 2019
Priority date	Sep 6, 2018
Publication date	Jan 25, 2022
Grant date	Jan 25, 2022

Abstract

A dosage measurement system is adapted to receive a motion from a dosage injection mechanism disposed within a drug injection pen. The dosage measurement system includes a substrate, a sensing capacitor disposed on the substrate, and a lifting tab. The sensing capacitor includes a dielectric layer disposed between a base plate and an adjustable plate. The lifting tab is attached to the adjustable plate and positioned to engage an undulation pattern disposed on a component attached to the dosage injection mechanism. The lifting tab is adapted to physically change a separation distance between the adjustable plate and the base plate in a reciprocal manner in response to the motion of the dosage injection mechanism and engagement with the undulation pattern. A capacitance of the sensing capacitor changes in response to the engagement of the lifting tab with the undulation pattern and the motion of the dosage injection mechanism.

First claim

What is claimed is:

1. An apparatus for use with a drug injection pen that dispenses a fluid, the apparatus comprising:
a dosage measurement system adapted to receive a motion from a dosage injection mechanism disposed within the drug injection pen, the dosage measurement system including:
a substrate;
a sensing capacitor disposed on the substrate, the sensing capacitor including a dielectric layer disposed between a base plate and an adjustable plate; and
a lifting tab attached to the adjustable plate and positioned to engage an undulation pattern disposed on a component attached to the dosage injection mechanism, wherein the lifting tab is adapted to physically change a separation distance between the adjustable plate and the base plate in a reciprocal manner in response to the motion of the dosage injection mechanism and engagement with the undulation pattern, wherein a capacitance of the sensing capacitor changes in response to the engagement of the lifting tab with the undulation pattern and the motion of the dosage injection mechanism.

2. The apparatus of claim 1 , further comprising:
capacitance change detection circuitry coupled to the sensing capacitor, wherein the capacitance change detection circuitry outputs a signal indicative of changes in the capacitance of the sensing capacitor; and
a controller coupled to the capacitance change detection circuitry, the controller including logic that when executed by the controller causes the controller to perform operations comprising:
tracking changes in the signal for determining a quantity of the fluid dispensed from the drug injection pen.

3. The apparatus of claim 2 , wherein the capacitance change detection circuitry comprises one of:
a capacitance divider that includes the sensing capacitor and a reference capacitor;
a relaxation based oscillator that includes the sensing capacitor;
a signal amplitude modulator that includes the sensing capacitor; or
a signal rise-time monitor that includes the sensing capacitor.

4. The apparatus of claim 2 , wherein the substrate comprises a circuit board and wherein the capacitance change detection circuitry and the controller are also disposed on the circuit board with the sensing capacitor.

5. The apparatus of claim 4 , further comprising:
a reference capacitor disposed on the circuit board and sharing the dielectric layer with the sensing capacitor, wherein the capacitance change detection circuitry comprises a differential comparator coupled to the reference capacitor and the sensing capacitor to cancel out manufacturing variations in the dielectric layer.

6. The apparatus of claim 1 , further comprising:
mounting pads disposed on the substrate; and
flexible anchor arms extending from the mounting pads to the adjustable plate and holding the adjustable plate over the base plate, wherein the flexible anchor arms flex in response to a force applied to the lifting tab by the undulation pattern thereby moving the adjustable plate.

7. The apparatus of claim 6 , wherein the substrate comprises a circuit board and wherein the mounting pads comprise solder pads to which the flexible anchor arms are soldered.

8. The apparatus of claim 1 , further comprising:
a second sensing capacitor disposed on the substrate, the second sensing capacitor including a second adjustable plate; and
a second lifting tab attached to the second adjustable plate and positioned to also engage the undulation pattern, wherein the second lifting tab is adapted to physically move the second adjustable plate in the reciprocal manner but out of phase from the lifting tab such that the lifting tab aligns with a valley of the undulation pattern when the second lifting tab aligns with a peak of the undulation pattern.

9. The apparatus of claim 1 , wherein the sensing capacitor is disposed on either:
a first side of the substrate that faces towards the undulation pattern; or
a second side of the substrate that faces away from the undulation pattern and the lifting tabs extends through a hole in the substrate or around an edge of the substrate to engage the undulation pattern.

10. The apparatus of claim 1 , further comprising:
a housing shaped to attach to the drug injection pen, wherein the first substrate, the sensing capacitor, and the lifting tab are at least partially disposed within the housing.

11. The apparatus of claim 10 , wherein the housing is shaped to attach to an end of the drug injection pen that is pressed by a thumb while dispensing the fluid.

12. The apparatus of claim 1 , wherein the undulation pattern comprises one of a sawtooth shape or a sinusoidal shape, and wherein the undulation pattern rises from the component, recesses into the component, or is cut around a perimeter of the component.

13. A method of measuring a volume of a fluid dispensed from a drug injection pen, comprising:
receiving a motion at a dosage measurement system disposed at least in part in a button attached to an end of the drug injection pen, the motion received from a dosage injection mechanism disposed within the drug injection pen when the drug injection pen dispenses a fluid;
reciprocally adjusting a physical offset between an adjustable plate of a sensing capacitor and a base plate of the sensing capacitor with a lifting tab attached to the adjustable plate, wherein the lifting tab engages an undulation pattern on a component attached to the dosage injection mechanism; and
measuring changes in a capacitance of the sensing capacitor, wherein the capacitance changes in response to engagement of the lifting tab with the undulation pattern while the dosage injection mechanism dispenses the fluid.

14. The method of claim 13 , further comprising:
tracking the changes in the capacitance over a time period, wherein the changes tracked enable determination of the volume of the fluid dispensed from the drug injection pen over the time period.

15. The method of claim 14 , wherein the sensing capacitor, capacitance change detection circuitry for measuring the changes in the capacitance of the sensing capacitor, and a controller for tracking the changes in the capacitance over the time period are all disposed on a common substrate.

16. The method of claim 13 , wherein measuring the changes in the capacitance comprises:
differentially comparing the capacitance of the sensing capacitor to a reference capacitance of a reference capacitor that shares a common dielectric layer with the sensing capacitor to cancel out manufacturing variations in the common dielectric layer.

17. The method of claim 13 , wherein measuring the changes in the capacitance comprises:
differentially comparing the capacitance of the sensing capacitor to a second capacitance of a second sensing capacitor disposed on a common substrate with the sensing capacitor, wherein a second lifting tab attached to a second adjustable plate of the second sensing capacitor engages the undulation pattern out of phase from the lifting tab such that the lifting tab aligns with a valley of the undulation pattern when the second lifting tab aligns with a peak of the undulation pattern.

18. The method of claim 13 , wherein the undulation pattern comprises one of a sawtooth shape or a sinusoidal shape, and wherein the undulation pattern rises from the component, recesses into the component, or is cut around a perimeter of the component.

19. The method of claim 13 , wherein the sensing capacitor is disposed on a substrate and wherein reciprocally adjusting the physical offset between the adjustable plate relative t

Assignees

• Verily Life Sciences Llc

Inventors

• Biederman William
• Jung Louis
• Frick Sean
• Collins Benjamin
• Bennett Eric

Classifications

• A61M5/20

  Automatic syringes, e.g. with automatically actuated piston rod, with automatic needle injection, filling automatically (A61M5/142 {, A61M5/46} take precedence; {hypodermic projectiles F42B12/54}) · CPC title

• A61M5/31568 Primary

  Means keeping track of the total dose administered, e.g. since the cartridge was inserted · CPC title

• A61M2205/8206

  battery-operated · CPC title

• A61M2205/3386

  Low level detectors · CPC title

• A61M5/3155

  by rotational movement of dose setting member, e.g. during setting or filling of a syringe · CPC title