Lead screw delivery device using reusable shape memory actuator drive
View Patent ↗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.
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, and
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.
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 , further comprises a post about which the first and second ratchet wheels are mounted rotatably.
4. The drive system according to claim 1 , wherein 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.
5. The drive system according to claim 1 , wherein 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.
6. 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.
7. 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.
8. 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.
9. The drive system according to claim 1 provided in a battery operated drug delivery device providing the drug container.
10. The drive system according to claim 1 , wherein the first ratchet wheel is provided with an insert portion providing radially flexible teeth, and wherein the second ratchet wheel is provided as a sleeve having rigid teeth provided radially on an interior surface thereof.
11. 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,
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.
12. 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, 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 a shaped memory alloy wire for resetting the shape memory alloy wire after the contraction incrementally driving the rotation of the second ratchet wheel; and
a the 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.
13. 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; and
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.
14. 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, 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 a shape memory alloy wire after the contraction driving incrementally the rotation of the second ratchet wheel;
operably connecting the 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.
15. The drive system according to claim 11 , further comprising a controller electrically connected to the shaped memory alloy to generate the contraction of the shaped memory alloy wire.
16. The drive system according to claim 11 , 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.
17. The drive system according to claim 11 , 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.
18. The drive system according to claim 11 , wherein the first and second ratchet wheels are arranged perpendicularly to the lead screw.
19. The drive system according to claim 11 , wherein 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.
20. The drive system according to claim 11 , wherein 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.