Method and device for the inspection of a condition of a cannula mounted on a syringe
A method for the inspection of a condition, in particular for the detection of defects, of a cannula (or injection needle) mounted on a syringe, which is located under a protective cap, and devices for carrying out such methods. A method includes measuring a magnetic field, in particular a magnetic field distribution, in the vicinity of the cannula. The presence of a ferromagnetic cannula causes a local change in the course of the magnetic field lines. This can be measured and used to determine whether the cannula, as desired, is arranged straight and coaxially to the syringe longitudinal axis, or whether it has a defect, such as being bent, kinked, compressed, broken/severed, oblique to the longitudinal axis of the syringe or eccentric to the longitudinal axis of the syringe.
1 . Method for inspecting a condition of a cannula which is mounted on a syringe and located in a cannula protective cap, comprising:
introducing the cannula into a magnetic field;
measuring said magnetic field in a vicinity of the cannula to obtain a measured magnetic field for the cannula; and
determining a deformation of the magnetic field, caused by said introducing the cannula into the magnetic field, compared to a case where the cannula is a straight cannula.
2 . Method according to claim 1 , wherein one or more magnetic field sensors are used to measure the magnetic field.
3 . Method according to claim 2 , wherein the one or more magnetic field sensors are designed as one-, two- or three-axis magnetic field sensors adapted to measure the magnetic field in one, two or three dimensions.
4 . Method according to claim 2 , wherein for measuring the magnetic field the cannula is moved relative to the one or more magnetic field sensors, wherein the syringe is rotated about its longitudinal axis and/or moved along its longitudinal axis, or the one or more magnetic field sensors are moved parallel to the longitudinal axis of the syringe.
5 . Method according to claim 1 , wherein the magnetic field is generated, at least in part by the earth's magnetic field, by an arrangement comprising one or more permanent magnets, or by an arrangement comprising one or more electromagnets, wherein the arrangement comprising one or more electromagnets also comprises one or more iron cores.
6 . Method according to claim 1 , wherein a magnetic shield is used to suppress magnetic interference fields.
7 . Method according to claim 1 , comprising a comparison of the measured magnetic field for the cannula with a measured magnetic field for a reference syringe with a mounted reference cannula located in a cannula protective cap having a desired condition, and a determination of the condition of the cannula mounted on the syringe based on the comparison.
8 . Method according to claim 7 , wherein the determination of the condition of the cannula mounted on the syringe is based on a comparison of an amplitude and/or phase position of the measured magnetic field for the reference cannula with an amplitude and/or phase position of the measured magnetic field for the cannula.
9 . Method according to claim 1 , comprising a transformation of a measured time course of the magnetic field from a time domain to a frequency domain.
10 . Method according to claim 1 , wherein the condition of the cannula is at least one of straight, bent, kinked, compressed, broken/severed, coaxial to a longitudinal axis of the syringe, oblique to the longitudinal axis, eccentric to the longitudinal axis.
11 . Device for inspecting a condition of a cannula which is mounted on a syringe and located in a cannula protective cap, comprising:
one or more magnetic field sensors for measuring a magnetic field in a vicinity of the cannula, after the cannula has been introduced to said magnetic field, to obtain a measured magnetic field for the cannula; and
a comparator adapted to compare, based on a deformation of the magnetic field caused by said introducing the cannula into the magnetic field, the measured magnetic field for the cannula with a measured magnetic field for a reference syringe with a mounted reference cannula located in a cannula protective cap having a desired condition and to determine the condition of the cannula mounted on the syringe based on the comparison.
12 . Device according to claim 11 , wherein the one or more magnetic field sensors are designed as one-, two- or three-axis magnetic field sensors adapted to measure the magnetic field in one, two or three dimensions.
13 . Device according to claim 11 , further comprising a means for moving the cannula relative to the one or more magnetic field sensors for rotating the syringe about its longitudinal axis and/or for moving the syringe along its longitudinal axis, or for moving the one or more magnetic field sensors parallel to the longitudinal axis of the syringe.
14 . Device according to claim 11 , further comprising an arrangement having one or more permanent magnets and/or an arrangement having one or more electromagnets for generating a magnetic field, wherein the arrangement comprising one or more electromagnets also comprises one or more iron cores.
15 . Device according to claim 11 , further comprising a magnetic shield for suppressing magnetic interference fields.
16 . Device according to claim 11 , wherein the comparator is designed to perform a comparison of an amplitude and/or phase position of the measured magnetic field for the reference cannula with an amplitude and/or phase position of the measured magnetic field for the cannula, and to determine therefrom the condition of the cannula mounted on the syringe.
17 . Device according to claim 11 , wherein the device performs Fourier transformation to transform a measured time course of the magnetic field from a time domain to a frequency domain.
18 . Device according to claim 11 , further comprising an output device for providing an output signal, which is adapted to indicate the condition of the cannula as at least one of straight, bent, kinked, compressed, broken/severed, coaxial to a longitudinal axis of the syringe, oblique to the longitudinal axis, eccentric to the longitudinal axis.