LEAD SCREW DELIVERY DEVICE USING REUSABLE SHAPE MEMORY ACTUATOR DEVICE

• US 20090143730A1
• Filed: 11/29/2007
• Published: 06/04/2009
• Est. Priority Date: 11/29/2007
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Diagnostics Operations Incorporated (Roche Holding AG)
• Inventors: Wiegel, Christopher, Roe, Steve N., De Polo, Marco C.
• Granted Patent: US 7,771,392 B2
• Time in Patent Office: Days
• US Class Current: 604/131
• CPC Class Codes: A61M 2205/0266 Shape memory materials
• CPC Class Codes: A61M 5/1452 pressurised by means of pistons
• CPC Class Codes: F03G 7/065 using a shape memory element

Abstract

A drug delivery device drive that includes a single shape memory alloy wire actuator to advance a lead screw via a ratcheting mechanism and method thereof are disclosed. In one embodiment, a shape memory alloy wire is operably connected to one of a pair of ratchet wheels and configured to drive incrementally the rotation of the connected ratchet wheel via a contraction, which in turn drives the rotation of the other ratchet wheel about a rotational axis which moves a lead screw and advances a plunger to dispense a liquid drug from a drug container. A drug delivery device using the shape memory alloy wire actuator in combination with the ratcheting mechanism to incrementally rotate a shaft, a lead screw or a sleeve provides for a more compact an less complicated design.

Claims

1. A drive system used to dispense a liquid drug from a drug container having a plunger, said drive system comprising:

a lead screw having a rotational axis and operably connected to the plunger;

a ratcheting mechanism having first and second ratchet wheels provided along the rotational axis, said first ratchet wheel is connected to the lead screw to move the lead screw; and

a shape memory alloy wire operably connected to the second ratchet wheel and configured to drive incrementally the rotation of the second ratchet wheel via a contraction, which in turn drives the rotation of the first ratchet wheel about the rotational axis which moves the lead screw and advances the plunger to dispense the liquid drug from the drug container.

2. The drive system according to claim 1, wherein the first and second ratchet wheels are arranged perpendicularly to the lead screw.

3. The drive system according to claim 1, wherein the first and second ratchet wheels each provided axially extended teeth which face each other.

4. The drive system according to claim 1, wherein the first and second ratchet wheels provide two opposing ratcheting surfaces with facing axially extended teeth which are spring biased for proper engagement.

5. The drive system according to claim 1, wherein the first and second ratchet wheels provide two opposing ratcheting surfaces with facing axially extended teeth which are spring biased for proper engagement via a spring, wherein the spring is also used to reset the shape memory alloy wire after the contraction driving incrementally the rotation of the second ratchet wheel.

6. The drive system according to claim 1, wherein the first and second ratchet wheels provide two opposing ratcheting surfaces with facing axially extended teeth which are spring biased axially for proper engagement via a torsion spring, wherein the torsion spring is also used to reset the shape memory alloy wire after the contraction driving incrementally the rotation of the second ratchet wheel.

7. The drive system according to claim 1, further comprises a post about which the first and second ratchet wheels are mounted rotatably, wherein the second ratchet wheel is spring biased axially on the post towards the first ratchet wheel via a torsion spring, the torsion spring having a first end mounted to the second ratchet wheel and a second end mounted to the post, wherein the torsion spring is configured to reset the shape memory alloy wire after the contraction incrementally driving the rotation of the second ratchet wheel.

8. The drive system according to claim 1, wherein the first and second ratchet wheels provide two opposing ratcheting surfaces with facing axially extended teeth which are spring biased axially for proper engagement, and the second ratchet wheel is spring biased radially to reset the shape memory alloy wire after the contraction incrementally driving the rotation of the second ratchet wheel.

9. The drive system according to claim 1, wherein the first and second ratchet wheels provide two opposing ratcheting surfaces with facing axially extended teeth which are spring biased axially for proper engagement via a torsion spring, and the second ratchet wheel is spring biased radially via a reset spring connected in opposition to the shaped memory alloy wire for resetting the shape memory alloy wire after the contraction incrementally driving the rotation of the second ratchet wheel.

10. The drive system according to claim 1, wherein the first and second ratchet wheels provide two opposing ratcheting surfaces having facing radially extended teeth.

11. The drive system according to claim 1, wherein the first and second ratchet wheels provide two opposing ratcheting surfaces having facing radially extended sets of teeth, wherein one set of the teeth are flexible, and the other set of the teeth are rigid.

12. The drive system according to claim 1, further comprising a controller electrically connected to the shaped memory alloy to generate the contraction of the shaped memory alloy wire.

13. The drive system according to claim 1, further comprising a controller electrically connected to the shaped memory alloy, and having capacitors for storing a charge used by the controller to generate the contraction of the shaped memory alloy wire.

14. The drive system according to claim 1, further comprising a controller electrically connected to the shaped memory alloy to generate the contraction of the shaped memory alloy wire and a hard stop mechanism electrically connected to the controller and configured to provide motion feedback of the ratchet mechanism.

15. The drive system according to claim 1, further comprising a sliding mechanism having a slot, wherein a pin of the ratchet mechanism fits into the slot of the sliding mechanism, and the shaped memory alloy wire drives the sliding mechanism parallel to the rotational axis.

16. The drive system according to claim 1, further comprising a sliding mechanism having a S-curve shaped slot, wherein a pin of the ratchet mechanism fits into the slot of the sliding mechanism, wherein the shaped memory alloy wire is configured to drive the sliding mechanism parallel to the rotational axis such that the S-curve shaped slot displaces the pin angularly about the rotational axis, thereby causing the rotation of the ratchet mechanism, and the incremental axial advancement of the lead screw.

17. The drive system according to claim 1 provided in a battery operated drug delivery device providing the drug container.

18. A method of dispensing a liquid drug from a drug container having a plunger, said method comprises:

operably connecting to the plunger a lead screw having a rotational axis;

providing along the rotational axis a ratcheting mechanism having first and second ratchet wheels, said first ratchet wheel being connected to the lead screw to move the lead screw;

operably connecting a shape memory alloy wire to the second ratchet wheel; and

driving incrementally the rotation of the second ratchet wheel via contracting the shaped memory alloy wire to drive the rotation of the first ratchet wheel about the rotational axis which moves the lead screw and advances the plunger to dispense the liquid drug from the drug container.

19. The method according to claim 18, wherein the first and second ratchet wheels provide two opposing ratcheting surfaces with facing axial extended teeth, said method further comprising using a torsion spring to spring biased the two opposing ratcheting surfaces for proper engagement of the facing axially extended teeth, and to reset the shape memory alloy wire after the contraction driving incrementally the rotation of the second ratchet wheel.

20. The method according to claim 18, further comprising providing a sliding mechanism with a S-curve shaped slot, fitting a pin of the ratchet mechanism into the slot of the sliding mechanism, using the shaped memory alloy wire to drive the sliding mechanism parallel to the rotational axis such that the S-curve shaped slot displaces the pin angularly about the rotational axis, thereby causing the rotation of the ratchet mechanism, and the incremental axial advancement of the lead screw.