Method and arrangement for acoustically testing the mechanical integrity of a cartridge
The present invention relates to a method of testing the mechanical integrity of a cartridge ( 10 ) containing a medicament and being arranged inside a drug delivery device ( 20 ). The invention also relates to a testing arrangement and to a respective drug delivery device, wherein the method comprises the steps of: acoustically stimulating the cartridge ( 10 ), measuring of the cartridge's ( 10 ) acoustic response ( 60 ) to the acoustic stimulation ( 32 ), comparing the acoustic response ( 60 ) with a standard response ( 62 ) of an intact cartridge ( 10 ), and determining the mechanical integrity of the cartridge ( 10 ) on the basis of the comparison.
1. A method of testing mechanical integrity of a cartridge containing a medicament and being arranged inside a drug delivery device, the method comprising:
acoustically stimulating the cartridge,
measuring an acoustic response of the cartridge to the acoustic stimulation,
comparing the acoustic response with a standard response of an intact cartridge, and
determining the mechanical integrity of the cartridge on the basis of the comparison,
wherein acoustically stimulating the cartridge comprises indirectly acoustically stimulating the cartridge by coupling a probe configured to emit acoustic signals to a device component of the drug delivery device, where the device component is in direct mechanical contact with the cartridge.
2. The method according to claim 1 , wherein acoustically stimulating the cartridge comprises emitting a series of acoustic signals of different frequency.
3. The method according to claim 1 , wherein the comparing of the acoustic response with the standard response is conducted on the basis of a power spectrum of the measured acoustic response and on the basis of a power spectrum of a standard response of an intact cartridge.
4. A drug delivery device for administering a liquid medicament, the device comprising:
a housing,
a cartridge filled with the medicament and arranged inside the housing, and
an indirect coupling comprising a bearing in direct contact with the cartridge and in direct contact with the housing, wherein the bearing comprises an ultrasound transmitting plastic material, wherein the indirect coupling forms a mount for the cartridge inside the housing and wherein the cartridge is at least one of axially clamped and radially clamped inside the housing by numerous protrusions extending and protruding inwardly from the housing.
5. The drug delivery device according to claim 4 , wherein the protrusions extended axially inwardly from a distal end of the housing and engage with a shoulder portion of the cartridge's distal end.
6. The drug delivery device according to claim 4 , wherein the protrusions comprise two O-rings separated from each other in axial direction and wherein the two O-rings are configured to clamp and to rigidly fasten the cartridge to an inside-facing sidewall portion of the housing.
7. The drug delivery device according to claim 4 , wherein the protrusions comprise numerous knob-shaped or nipple-shaped protrusions separated from each other in axial direction and configured to axially and radially clamp the cartridge inside the housing.
8. A method of testing mechanical integrity of a cartridge containing a medicament and being arranged inside a drug delivery device, the method comprising:
acoustically stimulating the cartridge,
measuring an acoustic response of the cartridge to the acoustic stimulation,
comparing the acoustic response with a standard response of an intact cartridge, and
determining the mechanical integrity of the cartridge on the basis of the comparison,
wherein the acoustically stimulating the cartridge comprises indirectly acoustically stimulating the cartridge by coupling a probe configured to emit acoustic signals to a drug delivery device's housing, which is acoustically coupled to a device component of the drug delivery device which is in direct mechanical contact with the cartridge.
9. The method according to claim 8 , wherein acoustically stimulating the cartridge comprises emitting a series of acoustic signals of different frequency.
10. The method according to claim 8 , wherein the comparing of the acoustic response with the standard response is conducted on the basis of a power spectrum of the measured acoustic response and on the basis of a power spectrum of a standard response of an intact cartridge.