1. Related U.S. Application Data
Provisional Application No. 60/753,447, filed Dec. 22, 2005 and Provisional Application No. 60/806,542, Filed Jul. 4, 2006.
2. Field of the Invention
The present invention relates to powered medical devices, systems for powering medical devices, and methods and uses of powered devices and power systems for a variety of medical purposes.
3. Description of the Prior Art
The use of medical and dental tools that utilize linear or circular motions to separate, attach, reshape, and remove soft-tissue, bone, teeth, and other types of living tissue is well known in the art. Medical drills for example are used in general and orthopedic surgeries, in common dental care, and in facial and other reconstructive procedures. Examples of other medical tools that utilize linear or circular motions include linear and circular staplers, linear and circular cutters, biopsy devices, suturing devices, drills, debriders, and tissue compactors. Linear and circular staplers and cutters utilize linear motions to form one or more lines of staples that attach two or more layers of tissue and can separate tissue layers in the center of the staple lines. Tissue compactors utilize circular motions to debulk removed tissue in order to enable passage of the removed tissue through narrow ports that are used for access in minimally invasive surgeries. Suturing devices utilize circular and linear motions to suture or attach various types of soft and hard tissue types. Biopsy devices utilize linear and circular motions to remove specific desired tissue samples and transport these samples to designated containers to be analyzed by pathologists.
All of the above mentioned medical and dental devices require a source of power in order to produce the necessary circular or linear motions. Various conventional methods for providing power to these devices have been utilized and such devices are well known in the art. Medical and dental drills commonly utilize electric motors, as exemplified by U.S. Pat. No. 4,705,038, U.S. Pat. No. 5,689,159 and U.S. Pat. No. 6,329,778, or mechanical motors energized by compressed air or compressed gas, as exemplified by U.S. Pat. No. 3,835,858, U.S. Pat. No. 4,109,735 and U.S. Pat. No. 7,008,224. Linear and circular staplers (and staplers that additionally contain cutters), utilize the surgeon or dentist supplied manual or hand power, as exemplified by U.S. Pat. No. 4,608,981 and U.S. Pat. No. 6,032,849, electric motors as exemplified by U.S. Pat. No. 5,954,259, U.S. Pat. No. 6,126,670 and U.S. Pat. No. 6,843,403, or mechanical motors energized by compressed air or compressed gas, as exemplified by U.S. Pat. No. 3,837,555, U.S. Pat. No. 4,349,028 and U.S. Pat. No. 5,397,046. In cases of medical or dental tools that use electric motors to generate circular or linear motions, either AC line power or DC battery power is utilized as the fundamental power source. In cases of medical or dental tools that make use of compressed air or compressed gas to generate circular or linear motions, either a compressor energized by AC line power or cartridges that contain pre-compressed air or pre-compressed gas are utilized as the fundamental power source.
Each of the above mentioned methods utilized to generate the power necessary to produce the desired circular or linear motions presents a set of technical limitations and other shortcomings, as explained below.
In the case of medical or dental tools that utilize electric motors that are energized by AC line power, or in the case of mechanical motors that are energized by compressors actuated by AC line power, significant disadvantages and limitations relate to the cost and complexity of such systems. For motors energized by AC line power or power supplies, a control circuit must be designed and provided to regulate the power delivered to the motor. These power supplies and the associated circuit boards, user interface, cabling, as well as the motors themselves, are complicated and expensive, provide difficulties for sterilization and are often not compatible with increasingly popular magnetic resonance imaging (MRI) diagnostics In the case of pneumatically driven mechanical motors, compressors must be supplied with adequate working pressure and airflow, and precision air motors designed to convert the pressurized airflow into useful mechanical energy can be very complicated and expensive. In both cases, these systems are further complicated and costs further increased because of the surgeon's need for instantaneous startup of the motor upon energizing and instantaneous stopping of the motor when power is turned off, which require additional design features to be added to the systems.
In cases of medical or dental tools that utilize electric motors energized by DC power sources such as batteries, one disadvantage and limitation includes the restricted electrical power available to such motors due to the size constraints of battery storage systems. Sterilization and shelf life considerations for battery powered systems further restrict device performance, and decreased battery reliability over time increases the risk of power loss during a medical procedure. When the batteries are made replaceable or rechargeable to circumvent some of the above limitations it unduly burdens the end user to maintain a ready supply of replacement batteries or separate charging systems for each device used, and to insure that the recharged battery is re-sterilized in preparation for its next use. These are significant limitations for battery powered systems.
In cases of medical or dental tools that utilize cartridges that contain pre-compressed air or pre-compressed gas, the disadvantages and limitations include pressure reduction within the pressure module over time, pressure fluctuations due to changes in ambient temperature, and safety risks such as the potential for high pressure leaks, the absence of pressure to actuate the device should a leak occur, and the associated surgical risks such as infection or failure to complete the procedure. The complexities and expense associated with ensuring integrity of the pneumatic path to prevent leaks and under-powering are significant drawbacks of these systems.
In cases of medical or dental tools that utilize surgeon or dentist supplied manual or hand-power a surgeon is required to pump a trigger or handle and the disadvantages and limitations include a lack of continuous hand power to effect the functional requirements of the device, inordinate levels of power required to effect actuation of the devices (which can be a significant disadvantage for physicians having limited hand strength), hand fatigue, unintended or secondary movements by the surgeon when attempting to actuate the device, and relatively long times required to actuate the devices.
Considering the technical limitations and shortcomings associated with the various methods utilized in prior art to energize and power medical and dental tools that require linear or circular motions, as described above, it is apparent that a safe, effective, and economically viable and readily available mechanical energy source could be most beneficial to patients, surgeons, dentists, and healthcare systems.
As will be described below, the present invention utilizes ultrasonic energy to overcome the above stated technical limitations and shortcomings. The use of ultrasonic energy in medicine is well known in the art. For example, ultrasonic imaging systems rely upon the transmission of ultrasonic signals to the body and subsequent recording of the reflected ultrasonic signals, followed by signal processing to generate a useful image of tissue. Exemplary prior art is disclosed in U.S. Pat. No. 5,740,128, U.S. Pat. No. 6,511,433 and U.S. Pat. No. 6,645,148.
Another common use for ultrasonic energy in medicine is the treatment of wounds or physical injuries, whereby ultrasonic energy is applied directly to the damaged tissue, most often transcutaneously, in order to generate a heating effect, increase blood flow or otherwise promote healing. Exemplary prior art is disclosed in U.S. Pat. No. 5,618,275, U.S. Pat. No. 6,685,656, U.S. Patent Application No. 20040171970A1.
Other common uses of ultrasonic energy are in dental tools and systems where ultrasonic vibrations are used for cleaning of teeth, roots, and debriding of bone in maxilo-facial procedures. For example, dental scalers are ultrasonic power systems commonly used in dental clinics, and ultrasonic toothbrushes are now widely used in the home. Exemplary prior art is disclosed in U.S. Pat. No. 5,150,492, U.S. Patent Application No. 20040023187A1, U.S. Patent Application No. 20050091770A1 and U.S. Patent Application No. 20050181328A1.
Other common uses of ultrasonic energy relate to therapeutic functions that rely on tissue effects such as ablation. Exemplary prior art is disclosed in U.S. Pat. No. 5,523,058, U.S. Pat. No. 6,126,619 and U.S. Patent Application No. 20040254569A1.
Another common use of ultrasonic energy is in general surgical procedures where ultrasonic vibrations are used for cutting and coagulation of blood vessels and soft tissue. Exemplary prior art is disclosed in U.S. Pat. No. 6,024,750, U.S. Pat. No. 6,036,667, U.S. Pat. No. 6,004,335 and U.S. Pat. No. 6,887,252.
In the above mentioned prior art where ultrasonic energy is used in surgical procedures for cutting and coagulation, ultrasonic power generators are used to supply the ultrasonic energy that is then transmitted to the treatment area. Such ultrasonic power generators are now widely available in surgical and dental facilities worldwide, as exemplified by commercial products such as the AutoSonix™ system by United States Surgical Corporation, the SonoSurg™ system by Olympus Surgical and Industrial America Inc., and the Harmonic™ system by Ethicon Endo-Surgery, Inc.
Regarding the prior art ultrasonic power systems used in surgical procedures for cutting and coagulation of tissue, or dental ultrasonic scalers used for cleaning teeth and bone, these systems generally consist of three main components: (1) an ultrasonic power generator (2) an ultrasonic transducer, typically embedded in a reusable handle held by the user and connected to the ultrasonic power generator by a cable, and (3) a plurality of instrument attachments, each containing an end-effector at the distal end that may be brought into contact with the target tissue, bone, or tooth in order to accomplish the desired medical or surgical effect. The ultrasonic power generator provides electrical signals that cause the ultrasonic transducer to resonate, thereby converting the electrical signals into high frequency, low amplitude (microscopic) mechanical vibrations that are operatively transmitted to the attached instrument and end-effector, which then also vibrates at high frequency and low amplitude. All of these prior art ultrasonic systems rely upon the generation, transmission, and application to the tissue of high frequency, low amplitude mechanical vibrations. At the tissue, for example, the frequency of vibration is typically in range of 20-200 kHz, the peak amplitude of vibration is typically in the range of 20-200 μm, and tip speeds are typically in the range of 2-20 m/s [1]. As a result, the mechanical forces generated by the devices on the tissue are limited, typically in the range of 0.1-1.0 N/mm. It is important to note that in all these prior art surgical devices, it is specifically the application of these high frequency, low amplitude mechanical vibrations directly to the target tissue that provides the medical effect and associated benefits.
There is considerable prior art involving the use of ultrasonic energy outside of the medical field. For example, one well developed area involves non-destructive testing or non-destructive evaluation, where ultrasonic energy, either transmitted or reflected, is used to inspect engineering structures for the presence of flaws or defects by employing imaging and signal processing methods [2, 3].
Another well established field involving ultrasonic energy relates to devices commonly known as ultrasonic (or piezoelectric) motors and actuators. Such motors and actuators have been explored for many years as potential alternatives to conventional electromagnetic motors [4, 5]. Exemplary prior art includes U.S. Pat. No. 4,019,073, U.S. Pat. No. 4,325,264 and U.S. Pat. No. 6,242,850, which are known as linear ultrasonic motors, and U.S. Pat. No. 4,484,099 and U.S. Pat. No. 5,336,958 which are known as traveling wave ultrasonic motors. In general, these ultrasonic motor and actuator technologies have achieved limited commercial success and are used in certain niche applications for micro-positioning and actuation, for example, in space exploration, electronics, optics, auto-focus cameras, automotive components, and the like, where small size, low power and high precision are required, or where special environmental considerations (e.g. vacuum or the presence of strong magnetic fields) preclude the use of conventional electromagnetic motors.
The present invention provides a new type of powered medical device, provides systems for powering a plurality of such devices, and discloses the use of these devices and systems for a wide variety of medical purposes. The present invention is based upon the conversion of high frequency, low amplitude mechanical vibrations generated by a transducer into macroscopic circular or linear motions, which are in turn converted by mechanical means into linear or rotary output motions having sufficient stroke, force, speed and precision to accomplish the desired medical tasks. Mechanical forces generated at the tissue by ultrasonically powered devices of the present invention far exceed anything possible with prior art ultrasonic surgical devices, thereby enabling a variety of medical mechanical procedures to be performed that were not previously not possible using ultrasonic energy sources.
In one preferred embodiment of the present invention, an ultrasonic power generator provides electrical signals to an ultrasonic transducer to produce the necessary high frequency, low amplitude mechanical vibrations. The basic principles employed to convert these mechanical vibrations into macroscopic mechanical motion are known in the art of ultrasonic motors and actuators. In the present invention, however, the mechanisms used to implement these principles have been uniquely adapted, combined with other mechanical elements, and configured in novel ways to create an entirely new class of powered medical devices that have unexpectedly been found to produce sufficient forces, speeds and other operating characteristics that are beneficial for a wide variety of medical purposes.
The devices and systems of the present invention, along with the methods and uses of these devices and systems disclosed herein, offer a number of unique advantages and overcome a number of important shortcomings and limitations of prior art powered medical devices. For example, devices of the present invention are simpler, smaller and less expensive to make and use, and are also easier and are more reliable to operate compared to prior art powered medical device technologies. This increases patient safety and lowers the overall cost of medical care. Further, compared to prior art powered medical devices, the devices of the present invention are uniquely capable of instantaneous startup and stopping when energized and de-energized, respectively, they hold fixed position and do not slip when de-energized, and are capable of generating significant mechanical forces that are substantially independent of the speed of actuation, all of which are uniquely beneficial features for many medical procedures. The devices of the present invention can be readily sterilized, and unlike conventional electromagnetic motors, they contain no magnetic components and are therefore completely compatible with MRI diagnostics. These unique features provide significant advantages over the prior art powered medical devices, especially for surgeons that are required to perform increasingly popular and precise minimally invasive endoscopic and laproscopic procedures. Additionally, ultrasonic power generators that may be readily used in systems of the present invention already exist in many surgical and dental facilities around the world, however their utility is currently limited to ultrasonic cutting and coagulation procedures and dental cleaning only. Therefore, by utilizing the devices and systems of the present invention, health care professionals that have previously purchased these expensive ultrasonic power generators will benefit from having a wider variety of medical uses for this equipment at their disposal, better justifying their initial capital investment.
Accordingly, it is evident that the devices and systems of the present invention provide a safe, effective, and economically viable alternative source for mechanical energy, which is superior to AC or DC (battery) powered motors, compressed air or compressed gas, and hand powered systems.
a illustrates the edge-drive linear friction principle employed to convert high frequency, low amplitude mechanical vibrations into macroscopic motion according to one embodiment of the present invention.
b illustrates the surface-drive linear friction principle employed to convert high frequency, low amplitude mechanical vibrations into macroscopic motion according to one embodiment of the present invention.
c illustrates a method of creating multiple points of contact between a single vibrating transducer and a driven member according to one embodiment of the present invention.
d illustrates a method of utilizing multiple vibrating transducers in contact with a single driven member according to one embodiment of the present invention.
a shows the maximum linear output force for the functional prototype device of Example 1 at each of 5 different power levels when the gear ratio was 20:1.
b shows the maximum linear output force for the functional prototype device of Example 1 at each of 5 different power levels when the gear ratio was 100:1.
c compares the linear output speed of the device of Example 1 for gear ratios of 20:1 and 100:1.
a shows the output rotary power of the device of Example 2 at each of 5 different power levels.
b shows the output rotary linear speed and rpm of the device of Example 2 at each of 5 different power levels.
In systems of the present invention, a power generator is connected and supplies electrical energy to a transducer capable of converting the electrical energy into high frequency, low amplitude mechanical vibrations. In one preferred embodiment of the present invention the power generator is an ultrasonic power generator and the transducer is an ultrasonic transducer (also known as a piezoelectric transducer), however it will be recognized by those skilled in the art that other types of power generators and transducers, for example magnetostrictive power generators and magnetostrictive transducers, may also be used to generate substantially similar high frequency, low amplitude mechanical vibrations from electrical energy.
In devices of the present invention, the high frequency, low amplitude mechanical vibrations generated by at least one energized transducer are operatively transmitted by frictional contact, either directly or indirectly via an intermediate vibrating component, to at least one driven member capable of producing macroscopic output rotary motion, linear motion or any combination thereof. The output motions are then transmitted to, and used to drive, at least one end-effector disposed toward the distal end of the device in order to accomplish the desired medical tasks. The driven member may also be configured along with other mechanical elements as part of a larger driven mechanism to further convert the macroscopic output rotary or linear motion produced by the driven member into other output linear or rotary motions that are then used to drive the end-effector. The end-effector may be connected directly to the driven member, it may be connected to the larger driven mechanism, or alternatively, it may be configured toward the distal end of a separate instrument attachment that may contain additional mechanical elements that further convert the output mechanical motion to better accomplish the desired medical function.
In one embodiment of the present invention, the devices are designed to be used as handheld appliances that, when operating, are connected to the power generator by an electrical cable. When in use, the handheld appliance is therefore comprised of the transducer, the driven member and end-effector. The entire handheld appliance, or any of the individual components comprising it, may be provided sterile within sterile packaging and intended to be used on a single patient (i.e. disposable), or may be designed to be sterilized repeatedly for reuse on one or more patients. Each of the individual components comprising devices of the present invention may be provided as an integral portion of, or separable or detachable from, the other system components.
Briefly, therefore, medical devices according to one embodiment of the present invention comprise:
Since a power generator is necessary to operate devices of the present invention, briefly therefore, systems of the present invention comprise:
Ultrasonic generators according to the present invention have maximum power ratings preferably between 1 and 2000 Watts, more preferably between 10 and 1000 Watts, and most preferably between 20 and 500 Watts, with a frequency of operation between 1 and 500 kHz, more preferably between 10 and 250 kHz, and most preferably between 20 and 150 kHz. In one embodiment of the present invention, the power generator is energized by AC line power, and further incorporates a controller providing a means for displaying and variably controlling the output power. Examples of such controllers providing such variable control means include, but are not limited to, switches, knobs, triggers, foot pedals, wireless transmitters, voice activation, and the like.
Ultrasonic transducers of the present invention are of the types that are commercially available, typically comprising a stack of piezoelectric ceramic elements, for example lead zirconium titanate (PZT) or similar, capable of generating high frequency, low amplitude vibrations when energized with a high frequency alternating voltage and current. According to one embodiment of the present invention, the transducer is an assembly that further comprises one or more matingly connected metallic elements designed to reflect and amplify the high frequency, low amplitude mechanical vibrations toward the distal or output end of the transducer assembly.
In the case of standing wave-type transducers used in one embodiment of the present invention, a metallic end-element commonly known as the horn acts as an acoustic waveguide to focus and amplify the ultrasonic vibrations produced by the transducer, where the resulting vibrations are primarily longitudinal in nature. Ultrasonic motors made using this type of transducer, and that utilize primarily longitudinal vibrations, are commonly known as linear ultrasonic motors and are the simplest type of ultrasonic motor. When the total length of the transducer assembly, including the horn, is tuned to the target resonant frequency, when driven by the ultrasonic power generator the entire assembly resonates and becomes a source of standing acoustic waves, where the peak amplitudes of vibration are typically in the range of 1-500 μm. Typically the horn is made from precision machined high strength aluminum alloy or titanium alloy, which exhibit good acoustic properties, and it's length must be tuned carefully to match the operating frequency of the power generator. According to one embodiment of the present invention, a standing wave-type of transducer is used to produce low amplitude longitudinal vibrations with peak amplitudes of vibration most preferably in the range of 20-200 μm.
In the case of traveling wave-type transducers used in an alternative embodiment of the present invention, the transducer elements are configured, tuned and excited in such a manner as to focus and amplify the ultrasonic vibrations produced by the transducer assembly into a traveling wave-like motion, where primarily flexural vibrations are utilized. These transducers are used in traveling wave-type ultrasonic motors, and can also be placed in frictional contact with the driven members of the present invention.
It should be obvious to those skilled in the art that other types of ultrasonic transducers, utilizing other modes of vibration, can also be used in devices of the present invention. Examples of vibration modes that may be used in frictional contact with the driven members of the present invention include longitudinal vibrations, lateral vibrations, flexural vibrations, torsional vibrations, and combinations of the foregoing.
According to one embodiment of the present invention, the vibrating transducer assembly is placed in direct contact with a driven member in order to convert the high frequency, low amplitude mechanical vibrations into macroscopic output rotary motion, linear motion, or any combination of rotary and linear motion. Alternatively, contact between the transducer and the driven member may be made indirectly using an intermediate vibrating component. In one preferred embodiment of the present invention, indirect contact is made using an optional resonator component that, during operation of the device, is matingly connected to the transducer and which to acts as an intermediate acoustic waveguide, focusing and transmitting the high frequency, low amplitude ultrasonic vibrations from the transducer to the driven member. The optional resonator component must also exhibit good acoustic properties and is therefore typically manufactured using similar materials and methods, and may be constructed or configured as an extension of, the transducer assembly. The use of the optional resonator component allows for optimizing the acoustic amplification and vibration characteristics needed to achieve efficient power transfer to the driven member, and provides additional design flexibility for positioning and optimizing the frictional contact between the transducer and driven member.
According to the present invention, during operation of the devices, the driven member brought into frictional contact with the vibrating transducer or vibrating optional resonator provides the mechanical means capable of generating useful output circular motions, linear motions, or combinations thereof. Driven members of the present invention may have many different shapes and the surface that makes frictional contact with the vibrating element may therefore be a curved surface, a flat surface, or combinations of curved and flat surfaces. Examples of driven members that may be used include wheels, gears, belts, linear bars, rings, arc segments, cams, linkages, and the like, as well as combinations of the foregoing. In one preferred embodiment of the present invention, the driven member is a wheel that is fixedly mounted on a shaft or axle that is capable of rotating about its axis. Driven members of the present invention may be constructed of common metals or alloys such as steel, brass, aluminum, titanium, and similar, or they may alternatively be constructed of ceramics, plastics, composites, and the like, or any combination of the foregoing. In one embodiment of the present invention, the driven member is constructed of a material that has a higher hardness than the material used to manufacture the vibrating transducer assembly or optional resonator to which it makes frictional contact during operation. In a preferred embodiment of the present invention, the driven member is constructed of hardened steel or ceramic.
According to one embodiment of the present invention, the driven member is configured as part of a larger driven mechanism, said driven mechanism further comprising other mechanical elements that convert the macroscopic motion generated by the driven member into more desired output mechanical motions. In one embodiment of the present invention the output mechanical motion is a rotary or circular motion. In another embodiment of the present invention the output mechanical motion is a linear motion. Combinations of linear and rotary output mechanical motions are also possible.
In one preferred embodiment of the present invention the driven mechanism comprises a driven member that is a wheel mounted on a shaft or axle that is capable of rotating about its axis, and further comprises additional gear elements and shafts to adjust and control the speed and force of the linear or rotary output mechanical motion. As will be obvious to those skilled in the art, additional gears, shafts, transmissions, linkages, clutches, couplings and the like may be optionally included in the driven mechanism to further convert and optimize the driven member output mechanical motion to have the force, speed and other operating characteristics desired for the intended medical purpose. The driven mechanism of the present invention may be provided as one or more assemblies or subassemblies that may further comprise various other electronic, magnetic or electromechanical elements designed to improve the performance and enhance functionality, safety or control. Examples of such other elements include indicators, switches, actuators, fuses, circuits, microprocessors, and the like.
According to the present invention, a plurality of end-effectors may be either singly or interchangeably connected to, and are driven by, the driven member or driven mechanism. During operation, the end-effector may further convert or modify the output mechanical motions, and transmits said motions to the target tissue to effectively utilize the output mechanical motions for the purpose of performing medical work. Examples of such end-effectors include, but are not limited to, linear staplers, linear cutters, circular staplers, circular cutters, biopsy instruments, suturing instruments, medical and dental drills, tissue compactors, tissue and bone debriders, clip appliers, grippers, extractors, and various types of instruments used in orthopedic surgery. It is to be understood within the context of the present invention that the end-effectors disclosed herein are included for illustration and explanation purposes, and are not to be considered as limiting the scope of the present invention with regard to the type of medical procedures, functions, effects, or uses of the mechanical work that may be performed upon tissue, bone, teeth, and the like. During operation of devices of the present invention, the end-effectors may be directly connected to the driven member or they may be connected indirectly via a driven mechanism. Further, the end-effector may be configured within a larger instrument attachment, wherein said instrument attachment either connects directly to the driven member, or indirectly via a driven mechanism, and where the end-effector is disposed toward the distal end of said instrument attachment.
As will be obvious to those skilled in the art, additional gears, shafts, transmissions, clutches, linkages, couplings and the like may be optionally included in the instrument attachment to further convert and optimize the output motion generated by the driven member or driven mechanism to produce the force and speed characteristics desired for the intended medical purpose. The instrument attachments of the present invention may be provided as one or more assemblies or subassemblies that may further comprise various other electronic, magnetic or electromechanical elements designed to improve the performance and enhance functionality, safety or control. Examples of such other elements include indicators, switches, actuators, fuses, circuits, microprocessors, and the like.
According to the present invention, the various individual components comprising the devices and systems may be configured to be matingly connected, joined together, and assembled or disassembled, both in manufacturing and during medical use, by any connection methods commonly known to those skilled in the art of electromechanical assemblies and medical devices. Examples of such methods include but are not limited to plug connections, pin connections, screw connections, press-fit connections, adhesive connections, snap connections, spring connections, flange connections, bayonet connections, and the like.
In one preferred embodiment of the present invention the entire handheld portion of the medical device, comprising the transducer, driven member and end-effector, is designed to be reusable, being provided as a unitary structure that is capable of undergoing repeated sterilization treatment prior to reuse on one or more patients.
In another embodiment of the present invention the entire handheld portion of the medical device, comprising the transducer, driven member and end-effector, is designed to be disposable, being provided sterile within sterile packaging and intended to be used on a single patient.
In still other embodiments of the present invention the various components and subassemblies comprising the medical device may be designed and intended to be either reused on one or more patients or disposed of after use on a single patient. Further the various components and subassemblies comprising the medical device may be provided either as an integral portion of, or separable or detachable from, other system components. For example, according to one preferred embodiment of the present invention a medical device comprises a first component further comprising a reusable handle containing the transducer, and a second component, detachable from the first and that may be either reusable or disposable, said second component further comprising the driven member and end-effector.
According to yet another preferred embodiment of the present invention, the medical device comprises a first component, further comprising a reusable handle containing the transducer, a second component, detachable from the first and that may be either reusable or disposable, said second component further comprising the driven member, and a third component, detachable from the second and that may be either reusable or disposable, said third component further comprising at least one end-effector. It will be obvious to those skilled in the art that other configurations involving unitary vs. detachable components, as well as reusable vs. disposable components, are possible within the broad scope of the present invention. Such alternative embodiments provide added flexibility according to the different needs and desires of the device manufacturer or medical professional.
While the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which particular embodiments are shown and explained, it is to be understood that persons skilled in the art may modify the embodiments herein described while achieving the same functions and results. Accordingly, the descriptions that follow are to be understood as illustrative and exemplary of specific structures, aspects and features within the broad scope of the present invention and not as limiting of such broad scope. Further, the methods and uses discussed herein shall not be construed as limiting the scope of the invention with regard to specific medical procedures or surgical applications, as they are only used as elucidating examples in which the present invention may be employed.
According to one embodiment of the present invention, the basic principles employed to convert high frequency, low amplitude mechanical vibrations generated by a standing wave-type transducer into macroscopic rotary motion are shown schematically in
In another embodiment of the present invention,
It is a claimed feature and benefit of the devices and systems according to the present invention that the output performance be optimized by maximizing the power transfer efficiency during the conversion from high frequency, low amplitude vibrations to medically useful output mechanical motions. Accordingly, and considering the basic principles for converting such high frequency, low amplitude vibrations as illustrated in
It is important to point out that while
As will be obvious to those skilled in the art, other configurations are also possible. For example, in another embodiment of the present invention (not shown), there may be more than one transducer and driven member subassemblies powering the same driven mechanism within a given medical device. According to another embodiment of the present invention (not shown), multiple points of contact between a single transducer and driven member may be accomplished utilizing a traveling wave-type of transducer assembly wherein the vibrating element attached to the transducer is in the form of a disk, sheet, ring, or similar shape. As a result of the flexural vibrations produced by these traveling wave-type transducer assemblies, more than one vibration amplitude peak exists that can therefore make multiple points of contact with a single driven member surface brought into frictional contact with said traveling wave-type of transducer.
Each of the handheld medical mechanical devices of system 200 further comprises a transducer 222 embedded within a handle 224, optional resonator 225, a driven member 226, and a specific instrument attachment (227, 237, 247, 257, 267) with end-effector (228, 238, 248, 258 and 268) needed to accomplish the desired medical function, namely surgical stapler 220 and 230, surgical or dental drill 240, surgical or dental debrider 250, and flexible rotating shaft surgical tool 260, respectively. Note that in surgical stapler 220, a squeezable trigger or handle 229 is further provided and may serve one or more functions. In one embodiment of the present invention, squeezable trigger 229 provides a controlling means for disengaging the driven mechanism, allowing the instrument attachment to retract to its original position via an embedded spring (not indicated). In another embodiment of the present invention, squeezable trigger 229 provides an alternative and sometimes more convenient controlling means compared to foot activation switch 206 for activating, de-activating and controlling the level of power to the device or its output speed.
During operation of system 200, when power generator 201 is energized and the operator activates foot switch 206 (or squeezable trigger 229), electrical energy is transmitted to the transducer within the reusable handle, which generates high frequency, low amplitude mechanical vibrations. The high frequency, low amplitude mechanical vibrations are transmitted either directly or indirectly via optional resonator 225 to the driven member 226, that converts the motion into macroscopic rotary or linear output mechanical motions appropriately optimized in terms of speed, stroke, force and other characteristics for use in the intended medical procedure. The macroscopic rotary and/or linear mechanical motions output by driven member 226 are further converted and modified by mechanical means within the instrument attachments 227, 237, 247, 257, and 267, and are then transmitted to and drive the end-effector, namely 228, 238, 248, 258 and 268, which is the distal portion of the instrument attachment where medical work on tissue, bone or teeth, and the like, is actually performed.
Device 230 provides an example of a handheld mechanical device according to one embodiment of the present invention, in this case also a surgical stapler, where the entire handheld portion of the device 232, which comprises transducer 222, driven member 226, instrument attachment 237, and end-effector 238 is designed to be provided sterile in a sterile package and intended to be disposed of after initial use on a single patient. In device 230, cable 208 that supplies electrical signals from the ultrasonic generator connects to the disposable handheld device 232 using cable connector 234.
To highlight other specific elements of this preferred embodiment, the left side view of device 300 is shown in
Driven wheel 310, together with the associated shafts, gears, transmission, etc. (i.e. elements 311-326 in
To further illustrate an important teaching according to devices of the present invention,
Referring to
Numerous other factors may be optimized in devices of the present invention to increase the output performance, improve power transfer efficiency, reduce noise, increase lifetime and reliability, or decrease manufacturing costs. For example, as shown in
As is known in prior art ultrasonic motors, and confirmed by experiment with devices of the present invention, certain combinations of materials used to manufacture the interacting frictional components (i.e. the transducer assembly or optional resonator and driven member) yield increased performance, improved efficiency, reduced noise, or increased lifetime and reliability. Accordingly, in one embodiment of the present invention, optional resonator 308 is produced from a metallic material that is acoustically efficient. The acoustic impedance of a material is defined as the product of the velocity of sound within the material and its density, and is a useful design parameter. In devices of the present invention, the vibrating components comprise materials having an acoustic impedance value preferably less than 5×107 kg/m2-s, more preferably less than 4×107 kg/m2-s and most preferably less than 2.5×107 kg/m2-s. In one preferred embodiment of the present invention the vibrating components are comprised of aluminum alloys, titanium alloys, or combinations thereof, in order reduce acoustic power losses. In a preferred embodiment of the present invention, optional resonator 318 is made from high strength aluminum alloy, such as 2000, 6000, 7000 series alloys, or the like. In another embodiment of the present invention, driven wheel 310 is made from a material that is harder and more wear resistant than the material of optional resonator 308. In a preferred embodiment of the present invention driven wheel 310 is made from hardened steel, titanium alloy, brass, nickel alloy or ceramic.
According to another embodiment of the present invention, the surface of the driven member is preferably modified in such a manner as to increase friction and decrease slippage at the region of contact between the frictional components. This may be accomplished by providing a surface having a non-smooth texture, for example through the use of non-smooth surface texture 418. There are numerous other methods known in the art for increasing frictional tractions between moving surfaces, and any of these methods may be utilized in devices of the present invention. For example, the surface of the driven member may be modified, treated or textured by machining, brushing, burnishing, knurling, sanding, roughening, grit blasting, or the application of surface coatings such as frictional coatings, abrasive coatings, and the like.
The devices of the present invention may further incorporate mechanisms and controlling means for generating both forward and reverse output motions, which can provide necessary or advantageous functionality for driving certain types of end-effectors.
b shows another embodiment of the present invention in which forward and reverse capability is achieved using two independent driven wheels that power a common output drive gear. Optional resonator 718 is supported by mechanical node supports 719 and is matingly connected to transducer assembly 720. In the configuration shown on the left, optional resonator 718 is brought into contact with a first driven wheel 721 that is fixedly mounted onto first shaft 722, along with first gear 723. Upon energizing, first driven wheel 721, first shaft 722 and first gear 723 are all caused to rotate clockwise 724. First gear 723 is engaged with output drive gear 725 that is mounted onto output drive shaft 726, both of which are therefore caused to rotate counterclockwise 727. The counterclockwise rotation 727 of output drive shaft 726 is a forward output mechanical motion. A second driven wheel 728 is fixedly mounted onto second shaft 729, along with second gear 730. Because second gear 730 is engaged with output drive gear 725, in the configuration shown on the left, second driven wheel 728 is caused to freely rotate clockwise 731. Alternatively, in the configuration shown on the right, optional resonator 718 is brought into contact with a second driven wheel 728 that is fixedly mounted onto second shaft 729, along with second gear 730. Upon energizing, second driven wheel 728, second shaft 729 and second gear 730 are all caused to rotate counterclockwise 732. Second driven wheel 728 is engaged with output drive gear 725 that is mounted onto output drive shaft 726, both of which are therefore caused to rotate counterclockwise 733. The counterclockwise rotation 733 of output drive shaft 726 is a reverse output mechanical motion. First driven wheel 721 that is fixedly mounted onto first shaft 722 along with first gear 723, and that is engaged with output drive gear 725 is caused to freely rotate counterclockwise 734. Thus, by providing a simple mechanical method (not shown) that moves the relative position of optional resonator 718 from being in contact with first driven wheel 721 to being in contact with second driven wheel 728, both forward and reverse output mechanical motion are achieved.
c shows another embodiment of the present invention in which forward and reverse capability is achieved by using an optional resonator that has two different tips, as follows. Optional resonator 735 is held in place by support flange 736 at the acoustic node, and has a left tip 737 and right tip 738, either of which may be brought into frictional contact with driven wheel 739. When energized by the transducer assembly (not shown), both the left tip 737 and right tip 738 vibrate as indicated by 740. As shown in the configuration on the left, when right tip 738 is brought into frictional contact with driven wheel 739, the tip produces elliptical oscillations 742 and driven wheel rotates counterclockwise 744, which is a forward output mechanical motion. Alternatively, when left tip 737 is brought into contact with driven wheel 739, the tip produces elliptical oscillations 745 and driven wheel 739 rotates clockwise 746, which is a reverse output mechanical motion. Therefore, by providing a simple mechanical means (not shown) of changing whether left tip 737 or right tip 738 makes frictional contact with driven wheel 739, both forward and reverse output mechanical motion are achieved.
d shows another embodiment of the present invention, similar to the mechanism of
According to one embodiment of the present invention shown in
According to another embodiment of the present invention shown in
An ultrasonic power system and ultrasonically powered device according to the present invention, configured to generate high force, linear output mechanical motion, as illustrated in
The handpiece was attached to a device body that was machined from Delrin™ plastic, into which was mounted an optional resonator, driven wheel, and moveable carriage assembly. The optional resonator had a threaded proximal end to accept and matingly attach to the transducer embedded within the handpiece. Said optional resonator was precision machined from 6061 aluminum alloy in the T6 heat treatment condition to have a total length that was generally in the range from 5.21 cm to 5.72 cm, and most optimally found to be between 5.33 cm and 5.59 cm. The optional resonator was fixedly mounted inside the device body using a flange support integrated into the optional resonator and having screw connections for mounting into the device body. The flange support was located at the position of an acoustic node, which was determined by experiment to be optimally located approximately 2.29 cm from the proximal end of said optional resonator.
The optional resonator was positioned in frictional contact along a surface near its distal tip with a hardened steel driven wheel approximately 1.59 cm in diameter and having a knurled surface texture produced by machining a series of angled grooves into its surface. The location of the region of contact between the optional resonator and the driven wheel was adjusted to the desired position by sliding forward or backward the portion of the device body to which the flange support was attached, thereby allowing the optional resonator to be positioned relative to the position of the driven wheel. For purposes of these experiments the moveable carriage assembly was positioned such that the angle of impingement between the driven wheel and the optional resonator was 0°. The force between the optional resonator and driven wheel was controlled and maintained constant by a steel spring attached at one end to the device body and at the other end to a moveable carriage assembly mounted on a pivoting shaft. The spring force was selected to be approximately 0.45 kg, resulting in a normal force being applied between the driven wheel and optional resonator of approximately 1.32 kg, taking into account the moment arm.
The driven wheel was fixedly mounted onto a 0.32 cm diameter rotating steel shaft held within the moveable carriage assembly, onto which was also fixedly mounted a drive gear 1.06 cm in diameter. The drive gear engaged a primary gear also 1.06 cm in diameter (gear ratio 1:1) mounted onto a 0.32 cm diameter primary drive shaft that extended out of the device body and into a transmission mounted onto the exterior of the device body using screw connections. The transmission consisted of a planetary gear assembly having an adjustable gear ratio, which for the purposes of these tests was selected to be either 20:1 or 100:1. The output shaft from the planetary gear assembly had an output gear approximately 0.95 cm in diameter fixedly mounted onto it, that was used to drive a 19 cm long linear steel rack. When the transducer was energized by the power generator, the driven wheel in frictional contact with the optional resonator was caused to rotate, said driven wheel rotation then being converted into linear motion by the driven mechanism and causing the linear rack to move in a forward direction.
To measure the performance of the device, the device body was supported within a test fixture configured to hold a 5.08 cm diameter compressible air cylinder to which was connected a pressure gauge having a dial readout, thereby serving as an a prototype medical end-effector simulating a surgical stapler. By placing the distal end of the linear rack in contact with the proximal end of the piston on the air cylinder, and then energizing the device, the linear rack moved in a forward direction, pushing the piston, compressing the air within the air cylinder, and thereby causing the pressure to increase within the cylinder. The pressure within the cylinder was monitored over time by observing the dial gauge and recording the pressure reading. By knowing the cylinder diameter, the actual linear output force generated by the device was calculated. To prevent damage to the device from excessive forces, a pressure relief valve was used and was set to prevent the force from exceeding 56.8 kg. The maximum force during a particular experiment was taken to be the lesser of the force at which linear travel of the rack and piston stopped or the maximum allowable force of 56.8 kg set by the pressure relief valve. A stopwatch and calipers were used to measure the distance and speed of travel of the rack and piston during each test. Tests were performed at each of the 5 available power level settings on the power generator, for two different gear rations, 20:1 and 100:1. The results of these experiments are shown in
a shows the maximum linear output force for the device at each of the 5 different power levels for the case when the planetary gear ratio was set at 20:1. The maximum linear output force for the device increased substantially linearly from approximately 11.4 kg to approximately 15.9 kg going from power level 1 to power level 4, then the force remained constant at 15.9 kg going from power level 4 to power level 5.
b shows the maximum linear output force for the device at each of the 5 different power levels for the case when the planetary gear ratio was increased to 100:1. The maximum linear output force for the device was approximately 45.5 kg for power level 1, however, at power levels 3-5 the maximum linear output force exceeded 56.8 kg, the maximum pressure allowed by the pressure relief valve.
While other device configurations are possible as described previously, the maximum linear output forces generated by both the 20:1 and 100:1 gear ratios in the functional prototype of Example 1 are significant and well suited for driving mechanical end-effectors for use in a wide variety of medical procedures. For example, these mechanical forces are sufficient to successfully perform a surgical stapling procedure.
c compares the linear speed of the device output at gear ratios of 20:1 and 100:1. For the 20:1 gear ratio, the linear speed of the device output increased from approximately 1.3 cm/s to approximately 4.2 cm/s as the power level increased from level 1 to level 5. For the 100:1 gear ratio, the linear speed of the device output increased from approximately 0.9 cm/s to approximately 2.4 cm/s as the power level increased from level 1 to level 4, however the speed remained constant going from power level 4 to power level 5. It is noteworthy from Example 1 that significant maximum linear output forces can be generated over a wide range of output speed, and this performance characteristic is potentially beneficial to surgeons when conducting certain medical procedures such as stapling or cutting.
An ultrasonic power system and ultrasonically powered device according to the present invention, configured to generate high speed rotary output mechanical motion was constructed and tested as follows. The device similar to that shown in
To measure the performance of the device, a string was attached to the output wheel and the device body was placed into a test fixture configured such that the output rotary motion was used to wind a string around the output wheel. A fixed weight of 0.25 kg was attached to the other end of the string, such that during operation, the drive shaft rotation caused the string to wind around the output wheel, thereby lifting the fixed weight against the force of gravity. This fixed weight and string configuration served as a prototype medical end-effector simulating a surgical or dental drill. A stopwatch and known length of the string were used to measure the distance and speed of travel during the test. Knowing the diameter of the output wheel, the fixed amount of weight lifted, and by calculating the speed, the output power was readily calculated. The tests were performed by varying the power level on the power generator from level 1 to level 5 and recording the linear speed generated by the output wheel. The results of these experiments are shown in
a shows the output power of the device of Example 2 as a function of generator power level. The output power level increased continuously from approximately 5.7 watts to approximately 11.3 watts as the power level increased from level 1 to level 5, however it appears that at level 5 the output power may have been nearing a maximum for this device configuration. Output power information such as shown in
b shows the linear speed and revolutions per minute (rpm) generated by the device output. In direct correlation with the output power of
While other device configurations are possible as described previously, the rotary output power and speed generated the functional prototype of Example 2 are significant and well suited for driving mechanical end-effectors for use in a wide variety of medical procedures. For example, these power and speeds are sufficient to successfully perform a surgical drilling procedure
A device capable of forward and reverse linear motion according to the method shown in
Number | Date | Country | |
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60753447 | Dec 2005 | US | |
60806542 | Jul 2006 | US |