Solenoid valve shock absorber

In one embodiment, a fluid dynamics system includes a solenoid valve including a valve body including ports including an inlet and outlet port, and a valve cavity having a direction of elongation and configured to provide fluid connectivity between ones of the ports, a solenoid coil disposed around valve cavity, and a plunger including a permanent magnet, and configured to move back-and-forth along the direction of elongation between a first and a second position in the valve cavity selectively controlling the fluid connectivity between respective ones of the ports, the valve body including shock absorber(s) to soften striking of the plunger against the valve body in the direction of elongation, and a controller configured to apply at least one current to the solenoid coil to selectively move the plunger between the first and second position, and to selectively maintain the plunger in the first position and the second position.

FIELD OF THE INVENTION

The present invention relates to medical systems, and in particular, but not exclusively to, fluid dynamics in medical systems.

BACKGROUND

A cataract is a clouding and hardening of the eye's natural lens, a structure which is positioned behind the cornea, iris and pupil. The lens is mostly made up of water and proteins and as people age these proteins change and may begin to clump together obscuring portions of the lens. To correct this, a physician may recommend phacoemulsification cataract surgery. In the procedure, the surgeon makes a small incision in the sclera or cornea of the eye. Then a portion of the anterior surface of the lens capsule is removed to gain access to the cataract. The surgeon then uses a phacoemulsification probe, which has an ultrasonic handpiece with a needle. The tip of the needle vibrates at ultrasonic frequency to sculpt and emulsify the cataract while a pump aspirates particles and fluid from the eye through the tip. Aspirated fluids are replaced with irrigation of a balanced salt solution (BSS) to maintain the anterior chamber of the eye. After removing the cataract with phacoemulsification, the softer outer lens cortex is removed with suction. An intraocular lens (IOL) is then introduced into the empty lens capsule restoring the patient's vision.

SUMMARY

There is provided in accordance with an embodiment of the present disclosure, a fluid dynamics system, including a solenoid valve including a valve body including ports including an inlet port and an outlet port, a valve cavity having a direction of elongation and configured to provide fluid connectivity between respective ones of the ports, and at least one shock absorber, a solenoid coil disposed in the valve body around the valve cavity, and a plunger including a permanent magnet, and configured to move back-and-forth along the direction of elongation between a first position and a second position in the valve cavity to selectively control the fluid connectivity between respective ones of the ports, wherein the at least one shock absorber is configured to soften striking of the plunger against the valve body in the direction of elongation, and a controller configured to apply at least one current to the solenoid coil to selectively move the plunger between the first position and the second position, and to selectively maintain the plunger in the first position and the second position.

Further in accordance with an embodiment of the present disclosure the plunger does not have a fixed rest position in the valve cavity.

Still further in accordance with an embodiment of the present disclosure the plunger does not include a restoring element configured to restore the plunger to a fixed rest position.

Additionally, in accordance with an embodiment of the present disclosure the plunger will not remain in the first position and second position without applying the at least one current to the solenoid coil.

Moreover, in accordance with an embodiment of the present disclosure the plunger will remain in the first position or the second position upon application of the at least one current to the solenoid coil.

Further in accordance with an embodiment of the present disclosure the valve body includes a first shock absorber and a second shock absorber configured to soften striking of the plunger against the valve body in the direction of elongation when the plunger strikes the valve body at the first position, and when the plunger strikes the valve body at the second position, respectively.

Still further in accordance with an embodiment of the present disclosure the first shock absorber and the second shock absorber do not include a spring.

Additionally, in accordance with an embodiment of the present disclosure the first shock absorber and the second shock absorber each include resilient material.

Moreover, in accordance with an embodiment of the present disclosure the resilient material includes one or more selected from the group consisting of silicone rubber, synthetic rubber, natural rubber, and polyurethane.

Further in accordance with an embodiment of the present disclosure the first shock absorber and the second shock absorber each include a flat surface facing the plunger.

Still further in accordance with an embodiment of the present disclosure the first shock absorber and the second shock absorber each include a rounded surface facing the plunger.

Additionally, in accordance with an embodiment of the present disclosure the first shock absorber and the second shock absorber each include a conical surface facing the plunger.

Moreover, in accordance with an embodiment of the present disclosure the controller is configured to apply a first current to the solenoid coil to activate the solenoid coil with a first polarity to cause the plunger to move and be maintained in the first position, and apply a second current to the solenoid coil to activate the solenoid coil with a second opposite polarity to cause the plunger to move and be maintained in the second position.

Further in accordance with an embodiment of the present disclosure the permanent magnet has a center with respect to the direction of elongation, the solenoid coil has a center with respect to the direction of elongation, and the valve body further includes a spacer coupled with the first shock absorber, to prevent the center of the magnet from moving in the direction of elongation past the center of the solenoid coil and maintain asymmetry between the center of the solenoid coil and the center of the permanent magnet with respect to the direction of elongation.

Still further in accordance with an embodiment of the present disclosure in the first position of the plunger, the plunger abuts the first shock absorber.

Additionally in accordance with an embodiment of the present disclosure, the system includes a medical tool including the solenoid valve, an irrigation channel, an aspiration channel which traverses the solenoid valve, and a sensor configured to provide a signal indicative of a fluid metric in the aspiration channel, the controller being configured to selectively control the fluid connectivity in the aspiration channel between the inlet port and the outlet port responsively to the fluid metric.

Moreover, in accordance with an embodiment of the present disclosure the fluid metric is a pressure level.

Further in accordance with an embodiment of the present disclosure the controller is configured to detect a rate of change of the fluid metric in the aspiration channel, and reduce the fluid connectivity between the inlet port and the outlet port responsively to the detected rate of change passing a given rate of change.

Still further in accordance with an embodiment of the present disclosure the controller is configured to increase the fluid connectivity between the inlet port and the outlet port responsively to the fluid metric passing a given value.

Additionally, in accordance with an embodiment of the present disclosure the medical tool further includes a probe body including a horn, a needle, a part of the irrigation channel and a section of the aspiration channel, and a fluid dynamics cartridge configured to be reversibly connected to the probe body, and including the sensor and the solenoid valve, which includes another section of the aspiration channel.

Moreover, in accordance with an embodiment of the present disclosure the fluid dynamics cartridge includes the controller.

There is also provided in accordance with another embodiment of the present disclosure, a fluid dynamics system, including a solenoid valve including a valve body including ports including an inlet port and an outlet port, a valve cavity having a direction of elongation and configured to provide fluid connectivity between respective ones of the ports, and at least one shock absorber, a solenoid coil disposed in the valve body around the valve cavity, and a plunger including magnetic material, and configured to move back-and-forth along the direction of elongation between a first position and a second position in the valve cavity to selectively control the fluid connectivity between respective ones of the ports, wherein the at least one shock absorber is configured to soften striking of the plunger against the valve body in the direction of elongation, wherein the at least one shock absorber includes a conical surface facing the plunger.

Further in accordance with an embodiment of the present disclosure the plunger does not have a fixed rest position in the valve cavity.

Still further in accordance with an embodiment of the present disclosure the plunger does not include a restoring element configured to restore the plunger to a fixed rest position.

Additionally, in accordance with an embodiment of the present disclosure the plunger will not remain in the first position and second position without applying at least one current to the solenoid coil.

Moreover, in accordance with an embodiment of the present disclosure the plunger will remain in the first position or the second position upon application of at least one current to the solenoid coil.

Further in accordance with an embodiment of the present disclosure the valve body includes a first shock absorber and a second shock absorber configured to soften striking of the plunger against the valve body in the direction of elongation when the plunger strikes the valve body at the first position, and when the plunger strikes the valve body at the second position, respectively.

Still further in accordance with an embodiment of the present disclosure the first shock absorber and the second shock absorber do not include a spring.

Additionally, in accordance with an embodiment of the present disclosure the first shock absorber and the second shock absorber each include resilient material.

Moreover, in accordance with an embodiment of the present disclosure the resilient material includes one or more selected from the group consisting of silicone rubber, synthetic rubber, natural rubber, and polyurethane.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Overview

During phacoemulsification of an eye lens, the emulsified lens particles are aspirated. When a particle blocks the inlet of an aspiration channel (which could be in a needle of a phacoemulsification probe) causing occlusion of the channel, the vacuum in the channel increases. When the channel becomes unblocked (e.g., by the particle being subsequently sucked down the channel), the high vacuum in the channel causes an aspiration surge known as a post occlusion surge, which may have traumatic consequences to the eye. For example, sensitive parts of the eye may be damaged or come into contact with the needle of the phacoemulsification probe.

A possible solution to the problem of vacuum level surge is incorporating an aspiration bypass. Such a bypass may consist of a small hole or channel between an irrigation channel of the probe and the aspiration channel. When a blockage occurs, the high vacuum diverts irrigation fluid into the aspiration channel via the hole, thereby limiting the vacuum level.

However, the above-described bypass aspiration technique is still prone to produce a traumatic aspiration surge when the channel unblocks, since the high vacuum is present in a long tube (which being flexible may also be compressed adding to the vacuum problem) between a portion of the aspiration channel inside the emulsification probe and the aspiration pump, and that large, partially vacant volume, may therefore cause a surge when the occlusion breaks. Moreover, diversion of irrigation fluid may cause an uncontrolled pressure-drop in the irrigation channel, which may also pose a risk to the eye.

Embodiments of the present invention generally solve the above problems by removing or reducing the pressure difference in the aspiration channel during the occlusion clearance. Embodiments of the present invention control fluid connectivity in the aspiration channel during occlusion clearance using an extremely fast-acting and programmable solenoid valve. The solenoid valve includes a solenoid coil which moves a plunger including a permanent magnet in a valve cavity. Two parts of the aspiration channel are connected to the valve cavity via ports in the valve cavity. Therefore, movement of the plunger in the valve cavity controls the fluid connectivity in the aspiration channel.

In some embodiments, the permanent magnet may be replaced by any suitable magnetic material, which is subjected to a force in a magnetic field, for example, but not limited to, iron, cobalt, nickel, gadolinium, and/or neodymium.

The solenoid valve does not need a restoring element (such as a spring) to keep the plunger in a rest position when a current is not applied to the solenoid coil. An electric current needs to be applied to the solenoid coil to selectively open the valve and keep the valve open, and to close the valve and keep the valve closed. If a current is not supplied to the solenoid coil, the position of the plunger may be unstable and unknown. Using a solenoid valve without a restoring element allows the plunger to be moved quickly with a selected force, while minimizing electrical power needed to open or close the valve thereby reducing heat generated by the solenoid valve. The solenoid valve is opened and closed by changing the polarity of the solenoid coil by changing the direction of the current applied to the solenoid coil.

In some embodiments, a spacer is placed in the path of the plunger preventing a center of the permanent magnet of the plunger (with respect to a direction of elongation of the valve cavity) from being aligned with a center of the solenoid coil (with respect to a direction of elongation of the valve cavity). In this asymmetrical state, the permanent magnet is not subjected to unstable forces from the solenoid coil and the plunger can be moved from one position to another by changing the polarity of the solenoid coil thereby providing a quick and effective opening and closing of the solenoid valve.

As the opening and closing of the solenoid valve is performed quickly and sometimes the solenoid valve is repeatedly opened and closed many times a second, the plunger may strike against a body of the valve causing a loud noise and vibration of a medical tool (such as a phacoemulsification probe) in which the valve is operating. The noise and vibration are disturbing for the physician operating the tool as well as making it difficult for the physician to steadily hold the tool. Therefore, in some embodiments, the solenoid valve includes one or more shock absorbers to soften the striking of the plunger against the valve body in the direction of elongation. The solenoid valve may include two shock absorbers placed at either end of the valve cavity to soften the striking of the plunger against the valve body as the plunger moves from one extreme to another within the valve cavity. The shock absorbers do not typically include springs. The shock absorbers are generally formed from a resilient material such as silicone rubber, natural rubber, synthetic rubber, or polyurethane. The shock absorbers may have any suitable shape. The shock absorbers include a surface which faces the plunger in use. This surface may have any suitable shape, for example, a flat surface, a rounded surface, or a conical surface.

In some embodiments, a sensor (e.g., pressure sensor, flow sensor, or any suitable sensor) connected to or coupled with the aspiration channel provides a signal indicative of a fluid metric (e.g., pressure level) in the aspiration channel and a controller selectively controls fluid connectivity along the aspiration channel by applying a suitable current to the solenoid coil to selectively open or close the solenoid valve. In some embodiments, when the controller detects a rate of change in the fluid metric (e.g., pressure level) in the aspiration channel passing (e.g., exceeding) a given rate of change, which is indicative of an occlusion breaking, the controller reduces fluid connectivity in the aspiration channel by closing the solenoid valve quickly (for example, in 10 milliseconds or less) thereby isolating the eye from the vacuum created in a majority of the aspiration channel and/or aspiration line until the pressure in the aspiration channel and/or aspiration line returns to a desired and/or safe pressure. The pressure in the aspiration channel may be changed, in a non-time critical manner, by adjusting or stopping an aspiration pump acting on the aspiration channel and/or by externally venting the aspiration line, and/or any other suitable method. Once the fluid metric (e.g., pressure level) in the aspiration channel passes a given value (e.g., given pressure level), the controller reopens the solenoid valve without causing a vacuum surge which could damage the eye.

In some embodiments, in addition to being linear, the solenoid valve is small and may be produced at low-cost thereby allowing the valve to be disposed of after use. Therefore, in some embodiments, the valve does not need to withstand repeated sterilization. The valve may be housed in a cartridge which is reversibly connected to the phacoemulsification probe and aspiration and irrigation tubes. The cartridge may then be removed from the probe and tubes after use for cleaning or disposal.

In some embodiments, sensors (e.g., a pressure sensor for the aspiration channel and a pressure sensor for the irrigation channel) may be included in the cartridge). Including the sensors in the cartridge may provide higher sensitivity to local changes in fluid dynamics and provide a higher degree of control of the pressure in the eye.

In some embodiments, the controller is also included in the cartridge. Including the controller in the cartridge may allow the controller to be configured for the calibration of the solenoid valve. Additionally, or alternatively, including the controller in the cartridge allows the controller to be close to the sensor or sensors which may be providing analog signals that could degrade if the signals needed to travel over a cable to a remote console in which the controller may otherwise be installed.

System Description

Reference is now made toFIG.1is a partly pictorial, partly block diagram view of a phacoemulsification system10constructed and operative in accordance with an embodiment of the present invention.

The phacoemulsification system10comprises a phacoemulsification probe12(e.g., handpiece). In some embodiments, the phacoemulsification probe12may be replaced by any suitable medical tool. As seen in the pictorial view of phacoemulsification system10, and in inset25, phacoemulsification probe12comprises a needle16, a probe body17, and a coaxial irrigation sleeve56that at least partially surrounds needle16and creates a fluid pathway between the external wall of the needle and the internal wall of the irrigation sleeve, where needle16is hollow to provide an aspiration channel. Moreover, irrigation sleeve56may have one or more side ports at, or near, the distal end to allow irrigation fluid to flow towards the distal end of the phacoemulsification probe12through the fluid pathway and out of the port(s).

Needle16is configured for insertion into a lens capsule18of an eye20of a patient19by a physician15to remove a cataract. While the needle16(and irrigation sleeve56) are shown in inset25as a straight object, any suitable needle may be used with phacoemulsification probe12, for example, a curved or bent tip needle commercially available from Johnson & Johnson Surgical Vision, Inc., Santa Ana, Calif., USA.

In the embodiment ofFIG.1, during the phacoemulsification procedure, a pumping sub-system24comprised in a console28pumps irrigation fluid from an irrigation reservoir (not shown) to the irrigation sleeve56to irrigate the eye20. The irrigation fluid is pumped via an irrigation tubing line43running from the console28to an irrigation channel45of probe12, the distal end of the irrigation channel45including the fluid pathway in the irrigation sleeve56. The irrigation tubing line43is typically flexible and may be prone to collapsing during an occlusion of the needle16. In another embodiment, the pumping sub-system24may be coupled or replaced with a gravity fed irrigation source such as a balanced salt solution (BSS) bottle/bag.

Eye fluid and waste matter (e.g., emulsified parts of the cataract) are aspirated via an aspiration channel47, which extends from the hollow of needle16through the phacoemulsification probe12, and then via an aspiration tubing line46to a collection receptacle in the console28. The aspiration is affected by a pumping sub-system26, also comprised in console28.

System10may include a fluid dynamics cartridge50(which in an embodiment, may be removable), which may include one or more valves to regulate the flow of fluid in the irrigation channel45and/or aspiration channel47as well as sensors, described in more detail with reference toFIGS.2A-6. Part of the irrigation channel45and the aspiration channel47is disposed in the probe body17and part is disposed in the cartridge50.

Phacoemulsification probe12includes other elements, such as a piezoelectric crystal52coupled to a horn54to drive vibration of needle16. The piezoelectric crystal is configured to vibrate needle16in a resonant vibration mode. The vibration of needle16is used to break a cataract into small pieces during a phacoemulsification procedure. Console28comprises a piezoelectric drive module30, coupled with the piezoelectric crystal52, using electrical wiring running in a cable33. Drive module30is controlled by a controller38and conveys processor-controlled driving signals via cable33to, for example, maintain needle16at maximal vibration amplitude. The drive module may be realized in hardware or software, for example, in a proportional-integral-derivative (PID) control architecture. The controller38may also be configured to receive signals from sensors in the phacoemulsification probe12and control one or more valves to regulate the flow of fluid in the irrigation channel45and/or the aspiration channel47, as described in more detail with reference toFIG.6. In some embodiments, at least some of the functionality of the controller38may be implemented using a controller disposed in the phacoemulsification probe12(e.g., the cartridge50).

Controller38may receive user-based commands via a user interface40, which may include setting a vibration mode and/or frequency of the piezoelectric crystal52, and setting or adjusting an irrigation and/or aspiration rate of the pumping sub-systems24/26. In some embodiments, user interface40and a display36may be combined as a single touch screen graphical user interface. In some embodiments, the physician15uses a foot pedal (not shown) as a means of control. Additionally, or alternatively, controller38may receive the user-based commands from controls located in a handle21of probe12.

Some or all of the functions of controller38may be combined in a single physical component or, alternatively, implemented using multiple physical components. These physical components may comprise hard-wired or programmable devices, or a combination of the two. In some embodiments, at least some of the functions of controller38may be carried out by suitable software stored in a memory35(as shown inFIG.1). This software may be downloaded to a device in electronic form, over a network, for example. Alternatively, or additionally, the software may be stored in tangible, non-transitory computer-readable storage media, such as optical, magnetic, or electronic memory.

The system shown inFIG.1may include further elements which are omitted for clarity of presentation. For example, physician15typically performs the procedure using a stereo microscope or magnifying glasses, neither of which are shown. Physician15may use other surgical tools in addition to probe12, which are also not shown in order to maintain clarity and simplicity of presentation.

Reference is now made toFIGS.2A-B, which are views of the phacoemulsification probe12for use with the system10ofFIG.1.FIG.2Ashows the cartridge50, which is configured to be reversibly attached (using a clip51) to the probe body17of the phacoemulsification probe12.FIG.2Bshows the cartridge50detached from the probe body17.FIG.2Bshows ports60of the irrigation channel45and the aspiration channel47on the probe body17for connecting with corresponding ports (not shown inFIG.2B, but shown inFIG.3A) of the cartridge50.FIG.2Balso shows irrigation tubing line43and aspiration tubing line46connected to ports62of the cartridge50.

Reference is now made toFIGS.3A-C.FIG.3Ais a schematic view of an interior of a fluid dynamics cartridge50for use in the phacoemulsification probe12ofFIGS.2A-B.FIG.3Bis a cross-section of the fluid dynamics cartridge50through line B:B ofFIG.3A.FIG.3Cis a cross-section of the fluid dynamics cartridge50through line C:C ofFIG.3A.

The phacoemulsification probe12may include sensors68, and70(which may be pressure sensors), and a solenoid valve64. In some embodiments, the cartridge50includes: the solenoid valve64, which includes ports62for connection to the irrigation tubing line43and aspiration tubing line46, ports66for connection to the ports60(FIG.2B), and sections of the irrigation channel45and aspiration channel47; the sensor68connected to the irrigation channel45; and the sensor70connected to aspiration channel47on the console28side of the solenoid valve64(as shown inFIG.3C). The sensor68and the sensor70are configured to provide respective signals indicative of respective fluid metrics (e.g., pressure levels) in the irrigation channel45and in the aspiration channel47. The aspiration channel47traverses the solenoid valve64.

Including the sensors68,70in the cartridge50may provide higher sensitivity to local changes in fluid dynamics and provide a higher degree of control of the pressure in the eye.

The phacoemulsification probe12may include a controller74to receive the signal(s) from the pressure sensor68and/or the pressure sensor70, and control the fluid connectivity in the irrigation channel45and/or the aspiration channel47by selectively opening and closing the solenoid valve64, responsively to the received signal(s). In some embodiments, the cartridge50may also include the controller74and/or a memory76(e.g., EEPROM) to hold calibration settings and/or a usage counter to count usage of the cartridge50and thereby prevent overuse of the cartridge50. In some embodiments, the controller74may be included in the console28(FIG.1). In some embodiments, the functionality of the controller74may be performed by the controller38. Including the controller74in the cartridge50may allow the controller to be configured for the calibration of the solenoid valve64. Additionally, or alternatively, including the controller74in the cartridge50allows the controller to be close to the sensors68,70which may be providing analog signals that could degrade if the signals needed to travel over the cable33to the console28in which the controller74may otherwise be installed.

The cartridge50is compact and may be any suitable size. In some embodiments, the cartridge50may fit into a cube of 2.5 cm sides.

The aspiration channel47includes a section47-1coupled to an inlet port66-1and a section47-2coupled to an outlet port62-1(as shown inFIG.3C). The controller74is configured to control the fluid connectivity in the aspiration channel47between the inlet port66-1and the outlet port62-1by selectively opening and closing the solenoid valve64, responsively to the fluid metric (e.g., pressure level) in the aspiration channel47. It should be noted that when the solenoid valve64is closed, the sensor70shown inFIG.3Cis configured to sense a fluid metric (e.g., pressure level) in the section47-2between the solenoid valve64and the console28.

The solenoid valve64and its operation is now described in more detail. The solenoid valve64includes a valve body78, a solenoid coil80, and a plunger82.

Reference is now made toFIG.3C. The valve body78includes the ports62, the ports66, a valve cavity84having a direction of elongation86and configured to provide fluid connectivity between respective ones of the ports62,66(e.g., between the inlet port66-1and outlet port62-1). The solenoid coil80is disposed in the valve body78around valve cavity84. The plunger82includes a permanent magnet88. The permanent magnet88may comprise all of, or only part of, the plunger82. For example, the plunger82may include the permanent magnet88coated or covered with a material of low friction. The plunger82is configured to move back-and-forth along the direction of elongation86between a position90and a position92in the valve cavity84selectively controlling the fluid connectivity between respective ones of the ports62,66(e.g., between the inlet port66-1and outlet port62-1). In some embodiments, the permanent magnet88may be replaced by any suitable magnetic material, which is subjected to a force in a magnetic field, for example, but not limited to, iron, cobalt, nickel, gadolinium, and/or neodymium.

The plunger82may have any suitable size, for example, a length in the range of 3 mm to 2 cm (e.g., 6 mm) and a diameter in the range of 1 mm to 1 cm (e.g., 3 mm). The valve body78may include a spacer94described in more detail with reference toFIGS.5A-Bbelow.

As the opening and closing of the solenoid valve64is performed quickly and sometimes the solenoid valve64is repeatedly opened and closed many times a second (as described in more detail with reference toFIG.6), the plunger82may strike against the valve body78causing a loud noise and vibration of the phacoemulsification probe12. The noise and vibration are disturbing for the physician15(FIG.1) operating the phacoemulsification probe12as well as making it difficult for the physician15to steadily hold the phacoemulsification probe12. Therefore, the solenoid valve64includes one or more shock absorbers96configured to soften the striking of the plunger82against the valve body78in the direction of elongation86. The solenoid valve may include two shock absorbers96(as shown inFIG.3C) placed at either end of the valve cavity84configured to soften the striking of the plunger82against the valve body78as the plunger82moves in the direction of elongation86from one extreme of the valve body78to another (e.g., from position90to position92, and vice-versa) within the valve cavity84. The shock absorbers96do not typically include springs. The shock absorbers96generally comprise, or are generally formed from, a resilient material such as silicone rubber, natural rubber, synthetic rubber, or polyurethane. InFIG.3C, the upper shock absorber96forms part of the spacer94.

The controller74(FIGS.3A-B) is configured to apply at least one current to the solenoid coil80to selectively move the plunger82between the position90and the position92, and to selectively maintain the plunger in the position90and the position92, as described below in more detail with reference toFIGS.5A-B.

Reference is now made toFIGS.3D-E, which are schematic views of the shock absorber96for use in the cartridge50ofFIG.3C. Each shock absorber96includes a flat surface97facing the plunger82(FIG.3C).

Reference is now made toFIGS.3F-G, which are cross-sectional views of alternative shock absorbers91,93for use in the cartridge50ofFIG.3C. Two shock absorbers91or two shock absorber93(or any suitable combination) may be used in the solenoid valve64instead of the shock absorbers96. The shock absorber91ofFIG.3Fincludes a conical surface95facing the plunger82. The shock absorber93ofFIG.3Gincludes a rounded surface99facing the plunger82.

Reference is now made toFIGS.4A-B, which are schematic views of a permanent magnet98in a solenoid coil100.

In the configuration ofFIG.4A, the polarity of the solenoid coil100is in the same direction as the polarity of the permanent magnet98. In such a configuration, if a center102of the permanent magnet98is moved a little away from a center104of the solenoid coil100, the permanent magnet98will oscillate around the center104of the solenoid coil100until the permanent magnet98settles so that the center102of the permanent magnet98is aligned with the center104of the solenoid coil100. The permanent magnet98therefore rests in a stable position with respect to the solenoid coil100.

In the configuration ofFIG.4B, the polarity of the solenoid coil100is in the opposite direction to the polarity of the permanent magnet98. In such a configuration, if the center102of the permanent magnet98is moved a little away from the center104of the solenoid coil100, the permanent magnet98will continue to move in that direction. The permanent magnet98inFIG.4Bis therefore in an unstable position with respect to the solenoid coil100.

Reference is now made toFIGS.5A-B, which are schematic views of operation of the solenoid valve64for use in the cartridge50ofFIGS.3A-C.

The plunger82is configured to move back-and-forth along the direction of elongation86between position92and position90in the valve cavity84selectively controlling the fluid connectivity between respective ones of the ports66,62. The controller74(FIGS.3A-B) is configured to apply current to the solenoid coil80to selectively move the plunger82between the position92and position90, and to selectively maintain the plunger in the position92and position90.FIG.5Ashows the plunger82in position92blocking fluid connectivity in the aspiration channel47.FIG.5Bshows the plunger82in position90allowing fluid connectivity in the aspiration channel47.

The plunger82does not have a fixed rest position in the valve cavity84. Even though in some orientations the plunger82may fall in one of the positions92,94due to gravity, if the solenoid valve64is orientated differently the plunger84may fall to a different position. The plunger82does not include a restoring element (e.g., spring) configured to restore the plunger82to a fixed rest position. The plunger will not always remain in the position92or position90(e.g., if the orientation of the phacoemulsification probe12is changed) without applying current to the solenoid coil80. In other words, for the solenoid valve64to function correctly, a current is applied to the solenoid coil80whether the solenoid valve64is to remain open or closed. The plunger82will remain in the position90or the position92upon application of current to the solenoid coil80.

The controller74is configured to apply a current to the solenoid coil80to activate the solenoid coil80with a polarity to cause the plunger82to move and be maintained in the position92as shown inFIG.5A. The controller74is configured to apply an opposite current to the solenoid coil80to activate the solenoid coil80with an opposite polarity to cause the plunger82to move and be maintained in the position90as shown inFIG.5B.

The permanent magnet88has a center106with respect to the direction of elongation86. The solenoid coil80has a center108with respect to the direction of elongation86.

The valve body78includes the spacer94to prevent the center106of the magnet88moving in the direction of elongation86past the center108of the solenoid coil80. Therefore, the spacer94maintains asymmetry between the center108of the solenoid coil80and the center106of the permanent magnet88with respect to the direction of elongation86so that the centers106,108are never aligned with respect to the direction of elongation86. The above asymmetry is desirable to allow movement of the permanent magnet88within the valve cavity84to be controlled and the maintained position of the permanent magnet88at the position90to be stable (as explained above with reference toFIGS.4A-B). When plunger82is in position90, plunger82abuts spacer94(seeFIG.5B).

The spacer94includes the upper shock absorber96. When plunger82is in position92, plunger82abuts the lower shock absorber96, and when plunger82is in position90, plunger82abuts the upper shock absorber96. The upper and lower shock absorbers96are configured to soften striking of the plunger82against the valve body78in the direction of elongation86when the plunger82strikes the valve body78at position90, and when the plunger82strikes the valve body78at position92, respectively.

Reference is now made toFIG.6, which is a flowchart200including steps in an exemplary method of operation of system10ofFIG.1. Reference is also made toFIG.3C.

The controller74is configured to apply (block202) a current to the solenoid coil80to activate the solenoid coil80with a polarity to cause the plunger82to move and be maintained in the position90so that the solenoid valve64is open (and kept open) and there is fluid connectivity along the aspiration channel47.

The controller74is configured to selectively control (block204) the fluid connectivity responsively to a measured fluid metric (e.g., a sensed fluid flow or pressure level) in the phacoemulsification probe12. In some embodiments, the controller74is configured to selectively control the fluid connectivity responsively to the fluid metric from the one or more sensors68,70coupled with aspiration channel47. In this embodiment, the sensor(s) detect a change in pressure, but this method is applicable to other types of sensors known in the art. The step of block204is now described in more detail with reference to sub-steps of blocks206-230.

The controller74is configured to receive a signal indicative of the fluid metric (e.g., pressure level) in the aspiration channel47from the sensor70(block206). The controller74is configured to detect a rate of change of the fluid metric (e.g., pressure level) in the aspiration channel47responsively to the received signal (block208). At a decision block210, the controller74is configured to determine if the rate of change passes (e.g., exceeds) a given rate of change. If the rate of change does not pass (e.g., exceed) the given rate of change (branch212), the method returns to the sub-step of block206. If the rate of change passes (e.g., exceeds) the given rate of change (branch214), the controller74is configured to reduce the fluid connectivity (block216) between the inlet port66-1and the outlet port62-1. The sub-step of block216may include the controller74being configured to apply a current to the solenoid coil80to activate the solenoid coil80with an opposite polarity to cause the plunger82to move and be maintained in the position92(block218). The solenoid valve64is closed and kept closed thereby blocking fluid connectivity in the aspiration channel47at the location of the plunger82thereby isolating the eye from the aspiration tubing line46(FIG.1) and protecting the eye from a vacuum surge.

In some embodiments, rather than the solenoid valve64closing completely and fast, the solenoid valve64may be controlled to close partially and/or slowly. In some embodiments, the activation of the solenoid valve64may also be controlled according to pressure, flow, temperature, or a combination of these type of sensed parameters.

The controller74is configured to reduce the vacuum in the aspiration tubing line46(block220) (and the portion of the aspiration channel47between the solenoid valve64and the aspiration tubing line46), for example, by reducing the action of the pumping sub-system26, or opening a vent in the aspiration tubing line46or in the aspiration channel47. The controller74is configured to detect the fluid metric (e.g., pressure level) in the aspiration channel47responsively to signal received from the sensor70(block222). At a decision block224, the controller74is configured to determine if the fluid metric (e.g., pressure level) passes (e.g., exceeds) a given value (e.g., given pressure level). If fluid metric (e.g., pressure level) does not pass (e.g., exceed) the given value (e.g., given pressure level) (branch226), the sub-step of block220is repeated. If the fluid metric (e.g., pressure level) passes (e.g., exceeds) the given value (e.g., given pressure level) (branch228), the controller74is configured to increase (block230) the fluid connectivity between the inlet port66-1and the outlet port62-1responsively to the fluid metric (e.g., pressure level) passing (e.g., exceeding) a given value (e.g., given pressure level), for example, the step of block202is repeated.