METHOD AND APPARATUS FOR DRIVING A TRANSDUCER OF AN INHALATION DEVICE

• US 20090217925A1
• Filed: 02/25/2009
• Published: 09/03/2009
• Est. Priority Date: 02/29/2008
• Status: Active Grant

• Current Assignee: MicroDose Therapeutx, Inc. (Teva Pharmaceutical Industries Limited)
• Original Assignee: Microdose Technologies Inc. (Teva Pharmaceutical Industries, Ltd.)
• Inventors: GUMASTE, ANAND, WEITZEL, DOUGLAS, BOWERS, JOHN
• Granted Patent: US 8,371,294 B2
• Time in Patent Office: Days
• US Class Current: 128/200.140
• CPC Class Codes: A61M 15/001 using ultrasonic means
• CPC Class Codes: A61M 15/0028 using prepacked dosages, one for each application, e.g. capsules to be perforated or broken-up
• CPC Class Codes: A61M 15/0085 using ultrasonics spraying or atomising liquids using ultrasonic vibrations in general B05B17/06
• CPC Class Codes: A61M 2202/064 Powder
• CPC Class Codes: B05B 17/0669 Excitation frequencies
• CPC Class Codes: B06B 1/0276 with simultaneous generation, e.g. with modulation, harmonics
• CPC Class Codes: H10N 30/802 Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits

Abstract

An inhaler is disclosed wherein medicament in a flat-bottomed container is aerosolized with a vibrator piezoelectric transducer. The transducer is driven by a signal that excites multiple harmonic frequencies to create a complex pattern of oscillations. A circuit for generating the drive signal to the transducer is also disclosed.

Claims

1. In an inhaler using a piezoelectric transducer as a vibrator, a method of driving the transducer, including providing a signal to the transducer to produce oscillations, the signal exciting a primary resonant frequency of the transducer and at least one secondary resonant frequency of the transducer.

2. The method of claim 1, wherein the signal is a waveform comprising two sinusoidal signals at two frequencies corresponding to the primary resonant frequency and the secondary resonant frequency.

3. The method of claim 1, wherein the transducer is used to aerosolize medicament contained in a blister pack.

4. The method of claim 3, wherein friction between the blister pack and the transducer due to the oscillations is minimized.

5. The method of claim 3, wherein the medicament is a dry powder.

6. The method of claim 3, wherein the medicament is a liquid.

7. The method of claim 1, wherein the transducer resonates at an nth harmonic of its primary resonance frequencies, wherein n is a whole number selected from the group consisting of 2, 4, 6 and 8.

8. A circuit for driving a piezoelectric transducer in an inhaler that uses a flat bottomed medicament container substantially in contact with the face of the transducer comprising:

a power supply;

a diode;

an inductor; and

an electronic switch, wherein the power supply, diode, inductor, and electronic switch are connected in series, the piezoelectric transducer is connected across the switch, and wherein the switch opens and closes at the lowest resonance frequency of the piezoelectric transducer.

9. The circuit of claim 8, wherein the electronic switch is comprised of at least one transistor.

10. The circuit of claim 9, wherein the electronic switch is comprised of two field effect transistors that open and close at the primary resonance frequency of the piezoelectric transducer.

11. The circuit of claim 9, wherein the inductor is sized to dump substantially all of its energy into the transducer when the switch is open.

12. The circuit of claim 9, wherein the circuit delivers substantial energy at harmonics of the lowest resonant frequency of the transducer and at least one secondary resonant frequency of the transducer.

13. In an inhaler comprising a piezoelectric transducer for facilitating suspension of particles of a medicament into an inhaled gas stream, a circuit for driving the piezoelectric transducer as claimed in claim 9.

14. The inhaler as claimed in claim 13, wherein the medicament is a dry powder.

15. The inhaler as claimed in claim 13, wherein the medicament is a liquid.

16. A method for minimizing friction between an oscillating transducer face and an element in contact therewith, which comprises driving the transducer at two or more frequencies corresponding to a primary resonant frequency and at least one secondary resonant frequency thereof.

17. The method of claim 16, wherein the transducer is driven at an nth harmonic of its primary resonance frequency, wherein n is a whole number selected from the group consisting of 2, 4, 6 and 8.