Piezoelectric fluid dispenser
Fluid delivery devices and methods are described, where the device may comprise a piezoelectric actuator operatively coupled to an ampoule with fluid, under a preloading force. The ampoule may comprise a thin-walled thermoplastic package which includes one or more apertures positioned on the wall of the ampoule. The piezoelectric actuator may be configured to clamp at least partially around the circumference of the ampoule and apply oscillations to its wall. The oscillations, typically in ultrasonic frequency, produce cycles of acoustic pressure in the fluid, leading to ejection of the fluid droplets or streams from the apertures.
1. A dispensing apparatus, comprising:
an ampoule containing a liquid to be dispensed and having a first portion and a second portion, wherein the first portion defines one or more apertures through a side wall of the first portion; and
an assembly which is configured to impart an oscillation onto the side wall such that a stream of the liquid is dispensed from the one or more apertures;
wherein the assembly is configured to engage with the side wall of the first portion partially, but not completely, around a circumference of the first portion.
2. The apparatus of claim 1 wherein the assembly is configured to secure the first portion and impart the oscillation onto the side wall.
3. The apparatus of claim 1 wherein the oscillation imparted upon the side wall comprises a primary oscillation to the first portion along a first direction such that a secondary oscillation is induced in the first portion along a second direction which is perpendicular to the first direction.
4. The apparatus of claim 3 wherein the primary oscillation and secondary oscillation are co-planar with one another and wherein the one or more apertures are aligned along the second direction such that the secondary oscillation dispenses the stream of the liquid through the one or more apertures.
5. The apparatus of claim 1 wherein the first portion defines a circular or oval cross-sectional shape.
6. The apparatus of claim 1 wherein the assembly comprises a vibratory structure that is configured as a clamp on the first portion of the ampoule.
7. The apparatus of claim 6 wherein the first portion is secured to the clamp via an interference fit.
8. The apparatus of claim 6 wherein an operating frequency of the assembly is near or at a resonance frequency of the assembly.
9. The apparatus of claim 6 wherein a clamping force of the clamp upon the first portion is less than 5 N.
10. The apparatus of claim 1 wherein the assembly is a piezoelectric assembly that comprises a bending transducer configured to oscillate in a bending mode.
11. The apparatus of claim 10 wherein the bending transducer comprises a bimorph actuator having a first piezoceramic layer, a second piezoceramic layer, and a passive layer between the first and second piezoceramic layers.
12. The apparatus of claim 11 wherein the passive layer comprises a printed circuit board.
13. The apparatus of claim 10 wherein the bending transducer comprises a unimorph actuator having a piezoceramic layer.
14. The apparatus of claim 10 further comprising electronic circuitry programmed to drive the piezoelectric assembly.
15. The apparatus of claim 1 wherein the oscillation amplitude is greater than 300 nm.
16. The apparatus of claim 1 wherein the liquid comprises ophthalmic medication.
17. The apparatus of claim 1 further comprising an optical alignment system which enables a patient to align the one or more apertures to a targeted region on a surface of an eye of a patient.
18. The apparatus of claim 1 , wherein the ampoule is substantially vertically oriented, and wherein the stream of the liquid is dispensed substantially horizontally.
19. The apparatus of claim 1 , wherein the stream of the liquid passes through a gap in the assembly when the stream of the liquid is dispensed.
20. The apparatus of claim 1 , wherein the stream of the liquid is dispensed substantially normal to a longitudinal axis of the assembly.