Phacoemulsification probe comprising magnetic sensors and/or multiple independent piezoelectric vibrators
A phacoemulsification device includes a phacoemulsification probe and a processor. The phacoemulsification probe includes a piezoelectric crystal configured to vibrate in response to a drive signal, a needle configured to be inserted into a lens capsule of an eye and to be vibrated by the piezoelectric crystal, and a set of magnetic-field components. The set includes (i) one or more magnetic-field generators configured to generate a magnetic field, and (ii) one or more magnetic-field sensors configured to sense the magnetic field. At least one of the magnetic-field components is coupled to vibrate with the needle and at least one other of the magnetic-field components is isolated from vibration of the needle, thereby causing the magnetic-field sensors to output signals indicative of the vibration. The processor is configured to adaptively adjust a frequency of the drive signal so as to vibrate the needle at a resonant frequency of the piezoelectric crystal.
1 . A phacoemulsification device, comprising:
a phacoemulsification probe having a longitudinal axis, comprising:
a piezoelectric crystal configured to vibrate in response to a drive signal;
a needle configured to be inserted into a lens capsule of an eye and to be vibrated by the piezoelectric crystal; and
a set of magnetic-field components, wherein the set comprises (i) at least one magnetic-field generator configured to generate a magnetic field, and (ii) at least one magnetic-field sensor configured to sense the magnetic field,
wherein the at least one magnetic-field generator and the at least one magnetic-field sensor are disposed at non-overlapping positions along the longitudinal axis,
wherein one of the at least one magnetic-field generator or the at least one magnetic-field sensor is configured to vibrate with the needle, and wherein the other one of the at least one magnetic-field generator or the at least one magnetic-field sensor is isolated from vibration of the needle, thereby causing the at least one magnetic-field sensor to output signals indicative of the vibration; and
a processor configured to:
determine a deflection amplitude and direction of the vibration by sampling the output signals at a sampling rate, and
adaptively adjust a frequency of the drive signal so as to vibrate the needle at a resonant frequency of the piezoelectric crystal based on the amplitude and the direction, wherein the at least one magnetic-field generator is configured to be operated at a frequency of 200 KHz, wherein the frequency of the at least one magnetic-field generator is higher than the resonant frequency of the piezoelectric crystal and is associated with the sampling rate .
2 . The phacoemulsification device according to claim 1 , wherein the output signals are indicative of at least one of the amplitude and the direction of the vibration of the needle.
3 . The phacoemulsification device according to claim 1 , wherein the at least one of the magnetic-field components in the set comprises a coil wound around a distal end of a horn of the phacoemulsification probe.
4 . The phacoemulsification device according to claim 1 , wherein the phacoemulsification probe further comprises a horn, wherein the horn is coupled with the needle, and wherein at least one of the magnetic-field components in the set is placed off a longitudinal axis of the horn.
5 . The phacoemulsification device according to claim 1 , wherein the magnetic-field components comprise one or more permanent magnets.
6 . The phacoemulsification device according to claim 1 , wherein the processor is further configured to calculate a derivative of the output signals with respect to time, and, in response to detecting that the derivative exceeds a given threshold, indicate to a user that the needle is engaging ocular media.
7 . A method for operating a phacoemulsification probe, the method comprising:
energizing a piezoelectric crystal of the phacoemulsification probe using a drive signal, wherein the phacoemulsification probe extends along longitudinal axis;
vibrating a needle of the phacoemulsification probe by the energized piezoelectric crystal;
outputting signals indicative of vibration of the needle using a set of magnetic-field components, wherein the set comprises (i) at least one magnetic-field generator configured to generate a magnetic field, and (ii) at least one magnetic-field sensor configured to sense the magnetic field, wherein:
one of the at least one of the magnetic-field generator or the at least one magnetic-field sensor is coupled with the needle to vibrate the needle,
the at least one magnetic-field generator and the at least one magnetic-field sensor are disposed at non-overlapping positions along the longitudinal axis
and the other one of the at least one of the magnetic-field generator or the at least one magnetic-field sensor is isolated from vibration of the needle;
determining a deflection amplitude and direction of the vibration by sampling the output signals at a sampling rate; and
adaptively adjusting a frequency of the drive signal so as to vibrate the needle at a resonant frequency of the piezoelectric crystal, based on the amplitude and direction,
wherein the at least one magnetic-field generator is configured to be operated at a frequency of 200 KHz, wherein the frequency of the at least one magnetic-field generator is higher than the resonant frequency of the piezoelectric crystal and corresponds to the sampling rate.