Abstract:
The present invention relates to a novel device with an ultrasonic based drill and corer. The invention uses ultrasonic and subsonic vibrations, which is produced by a frequency compensation coupler or free mass, to produce the hammering action with relatively low axial-force required. The invention can also be fitted with irrigation and aspiration capabilities. The invention is furnished with a body sensor-feedback apparatus, which provide feedback to the operator as to the optimal frequency and power use of the generator. The assembly presented also has a coolant jacket to keep the drill or coring apparatus at optimum temperature prolonging the life of the instrument and the quality of the sample. The invention can be used in numerous applications one of such notable application is on the field of orthopedics.

Description:
This application is a conversion of U.S. Provisional Patent Application Serial No. 60/279,427 filed Mar. 28, 2001. This application does not claim priority to co-pending U.S. patent application Ser. No. 09/518,801 filed Mar. 3, 2000 entitled “Method and Apparatus for Cleaning Medical Instruments and the like”. 
    
    
     BACKGROUND OF THE INVENTION 
     FIELD OF THE INVENTION 
     The present invention relates to a novel system with an ultrasonic based drill and corer. More particularly, the invention uses a combination of ultrasonic and sonic vibrations to produce a hammering effect with relatively low axial-force. In addition, the invention relates to orthopedic applications such as bone grafting and hip replacement. Also, the invention can be used in applications such as brain shunt cleaning that require irrigation and aspiration capabilities. The present invention also has a body sensor-feedback apparatus, which provides feedback to the operator as to the optimal frequency and power use of the ultrasonic generator. 
     BACKGROUND OF THE INVENTION 
     Many applications require effective drilling and coring to make holes or extract materials. Such applications can include but are not limited to planetary exploration, military, medical operations, and geologic exploration. Existing drilling and coring techniques for these applications are limited by the need for large axial forces, great power consumption, and the use of a heavy mechanism to accomplish the drilling or coring. Drilling a small hole or coring a small sample of material is difficult because the large axial forces required to drill through or core the material. Other areas of concern associated with conventional drills is the need for high axial load and that they are subject to drill tip jamming, breaking, dulling and are difficult to use in drilling non-horizontal or hard surfaces. For example, non-horizontal or hard surfaces require the use of large and heavy platforms to support the drill. The drilling process can also be hampered by the accumulation of drilling debris in the drilling area. 
     The invention disclosed hereby can drill through all sorts of materials and can be used for biomedical applications such as bone grafts or use for geological studies. Although prior art shows or suggest various methods or apparatus for bone grafting, irrigation and aspiration during procedures and sensing mechanism, it is apparent to those skilled in the art that more efficient and easier methods are desirable. The present invention provides the needed improvements over the prior art. In addition, it will be apparent that this invention is well suited for very diverse applications from planetary exploration to medical operations. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus that uses a combination of ultrasonic and subsonic vibrations to perform effective drilling and coring. The device can be used for multiple applications in which drilling and/or coring is required. The present invention presents a low power, misalignment-tolerant device that exhibits a self-extracting debris process. The device can be further modified to include irrigation and aspiration capabilities. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 a  and  1   b  depict the components of the invention in an exploded fashion in the order in which the components are fitted together. 
     FIGS. 2 a  and  2   b  show a cross sectional views of the ultrasonic floating probe with the internal and external cooling jacket and condom. 
     FIG. 3 shows a flowchart for the feedback loop for displacement sensing of the body sensor. 
     FIGS. 4 a  and  4   b  shows a cross sectional view of a section of the ultrasonic floating probe that illustrates the piezoelectric sensing crystals. 
     FIGS. 5A and 5B show another cross sectional view of a section of the ultrasonic floating tip that illustrates the frequency compensation coupler or free mass. 
     FIGS. 6 a , b, c , and  d  show different assemblies for the ultrasonic floating probe. 
     FIG. 6 e  depicts a multiple piece plastic probe. 
     FIG. 6 f  depicts a one-piece plastic probe 
     FIGS. 7A and 7B show a series of tip configurations that can be used on the ultrasonic floating probe according to the application. 
     FIG. 8 shows a cross sectional view of the ultrasonic floating probe with irrigation and aspiration capabilities. 
     FIG. 9 illustrates the ease of use of the ultrasonic floating probe during drilling or coring. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in detail, for ease of the reader, like reference numerals designate identical or corresponding parts throughout the views depicted in the drawings. It should be noted that a drawing does not depict each embodiment of the present invention; nor is each of the notable applications of the present invention depicted by a drawing. The device uses a floating-head drilling mechanism, where high frequency ultrasonic vibrations are induced by an ultrasonic generator. 
     FIG. 1 shows the present invention. The ultrasonic frequencies are generated by a piezoelectric stack actuator  60 , shown in FIG. 2 a . The high frequency vibrations generated by the generator are enhanced by an ultrasonic horn  64 . Probe  11  or drill bit is inserted into horn  64 , which, in turn, is driven by the generator. Probe  11  is not, however, fixedly secured to horn  64 . Barrier member  51  covers horn  64  and possesses an opening large enough for the probe tip  11  to fit through. Probe  11  also has capturing member  50  that is fitted on probe  11  closer to the end of probe  11  that is to be inserted into horn  64 . Capturing member  50  is larger that the opening in barrier member  51  and prevents probe  11  from disengaging horn  64  completely. Thus, capturing member  50  is located between horn  64  and barrier member  51 . This construction is also shown in FIGS. 5 a  and  5   b . This is called a floating probe because probe  11  actually disengages from horn  64  during the ultrasonic frequency cycles. However, probe  11  can only disengage so much since the combination of the capturing member and the barrier member prevent the probe from disengaging completely. In addition, spring  20  can be utilized with the present invention. Spring  20  is located between capturing member  50  and barrier member  51  and provides extra force in pushing probe  11  (and the capturing member) back into horn  64  after the probe disengages the horn. 
     The barrier member can take many geometric shapes, two of which are shown in the drawings of this application. However, one of ordinary skill in the art will readily appreciate that the barrier member could take many different geometric shapes so long as the barrier member has the opening to allow the probe to fit through and provides a surface to stop the capturing member (and the probe) from completely disengaging from the horn. 
     FIG. 1 also depicts the free mass or frequency compensation coupler  101  that can be used with present invention to enhance the conversion of the ultrasonic frequencies to subsonic frequencies. The frequency compensation coupler or free mass  101  is a metal disk that slidably engages probe  11 . One of ordinary skill in the art should appreciate that other materials of various shapes could be used in the construction of frequency compensation coupler  101 . Frequency compensation coupler  101  is located between the capturing member of probe  11  and the end of probe  11  that fits horn  64 . Frequency compensation coupler  101  converts ultrasonic action to subsonic action. This is desirable in some applications because the subsonic action creates less heat and friction than ultrasonic action. The phrase “free mass” as used herein is defined as a piece of material (metal or otherwise) that is not physically attached to any other component. Frequency compensation coupler or free mass  101  is located between the horn  64  and the proximal end of the ultrasonic probe  11 , and is used to enhance the jack-hammering effect of the ultrasonic drill/corer for certain applications. Horn  64  amplifies the ultrasonic vibrations that are induced by ultrasonic generator. The free mass oscillates between the horn and the capturing member of the probe. 
     One of ordinary skill in the art will readily appreciate that frequency compensation coupler  101  can vary in size, shape and weight. The factors depend on the size of transducer horn  64 , probe  11  and on the frequency output at which the device is to be operated. For applications such as drilling hardened materials, as described herein, the free mass is optimally ¼ inch in diameter. However, one of ordinary skill in the art will appreciate that the diameter of free mass  101  is dependent on the size of horn  64  and probe  11 . For applications such as the removal of pacemaker leads, free mass  101  is also optimally ¼ inch in diameter. However, in this application, the diameter of the probe is dependent on the diameter of the lead to be removed. Thus, the free mass, in this particular application, is also a function of the lead to be removed. 
     FIG. 2 a  shows the piezoelectric crystals that generate the ultrasonic frequencies that emanate to the horn. FIG. 2 a  also depicts an internal cooling jacket  85  which can be extended over the crystals or restricted only to the horn area. 
     FIG. 2 b  shows probe  11  with internal cooling jacket  85 . Internal cooling jacket  85  requires that horn  64  have a solid top or barrier  87  between probe  11  and the bottom of horn  64  so that fluid can be injected through catheter  80  against the solid top to cool down the probe and horn. Internal cooling jacket  85  can be extended toward piezoelectric ceramics  60  or restricted only to horn  64  area. FIG. 2 b  depicts a probe with internal cooling jackets  85  and external cooling jackets  83 . Internal cooling jacket  85  as explained above requires that horn  64  have a solid top or barrier  87  between probe  11  and the bottom of horn  64 . The fluid coolant is pulsed at solid top  86  and flows back out around the sides of the catheter. The housing of external cooling jacket  83  is placed over probe  11  and horn  64  so that probe  11  and horn  64  are constantly receiving cool fluid. The cool fluid is added through catheter  81 . Also an internal and external coolant condoms  82  are depicted on the figure. The internal and external coolant condoms and fittings are present in the invention to prevent coolant from leaking from the apparatus. These coolant condoms are only necessary with the use of the external cooling jacket. The internal coolant condom is a silicon disc that is placed along the interior of the top of the external cooling jacket. External coolant condom  82  is a piece of finger cotton that is stretched over the top of probe  11  and external-cooling jacket  83 . Piezoelectric crystals  60  can also be observed in this figure. 
     FIG. 2 b  depicts the two methods of cooling the device. As shown in FIG. 2 b , water can enter at either point A or point B. The water flows around the device, cooling the device as the water swirls around. The water then exits through point C. In addition, FIG. 2 b  shows that a fitting D can replace the external coolant condom to keep the water from flowing along the length of the probe. 
     FIG. 3 shows a flowchart for the feedback loop for displacement sensing of the body sensor. The feedback loop is provided to the operator as to the optimal frequency and power use of the generator. To enable the feedback, at least two thin piezoelectric crystals  89 , which will function as sensing ceramics, will be placed near big piezoelectric crystals  88 , or driving ceramics. When driving ceramics  88  are energized, they will put a force on sensing ceramics  89 . This force is translated to an electrical signal and sent to microprocessor  91 . The translation of the force is accomplished by attenuator  97 , rectification  96 , filter  95  and A/D source  98 . Microprocessor  91  then calculates the frequency and power outputs and can adjust the frequency and power output to the user&#39;s requirements. The required change in frequency is done by frequency synthesizer  92 , and a change in power by output driver stage  94 . This device provides an instantaneous reading as to the optimal settings under which the transducer assembly should operate. This allows the transducer assembly to stay in tune throughout the use of the transducer. 
     FIGS. 4 a  and  4   b  show a cross sectional view of a section of the ultrasonic floating probe that illustrates piezoelectric sensing crystals  90  in connection with body sensor feedback apparatus described and shown in FIG.  3 . FIG. 4 illustrates the location and connection between the driving crystals, which produce the ultrasonic frequencies, the sensing crystals, which provide the feedback to the microprocessor, in the context of an ultrasonic device as contemplated by the present invention. Piezoelectric sensing ceramics  90  are very thin in comparison with piezoelectric driving ceramics  88 . The encased biasbolt  100  and horn  64  can also being appreciated in the figure. The stepped horn  64  shape offers the greatest displacement magnification when compared to other geometries of horns. The biasbolt or stress bolt  100  is used contain the transducer assembly and maintain the strength of the piezoelectric ceramics. If a drill/corer head with a hollow center to create a coolant path is desired the bolt can be replaced with a threaded tube either placed at the center of the piezoceramics stack or, in an alternative embodiment, external to the stack encircling the sandwich piezoceramics. Driving ceramics  88  when energized will put a force on thin piezoelectric crystals  90 . This force will be translated into electrical signals, which will result in a feedback providing instantaneous readings with optimal settings under which the transducer assembly should operated. 
     FIG. 5 a  shows another cross sectional view of a section of the ultrasonic floating tip that illustrates the frequency compensation coupler. In this close up view of the proximal end of ultrasonic probe  11  the tip of transducer  13  can be observed in relationship with frequency compensation coupler or free mass  101 . The frequency compensation coupler or free mass is a metal disk or other suitable material. Frequency compensation coupler or free mass  101  fits over floating probe  11  and is located between capturing member  50  of probe  11  and end of the probe  12  that fits into the horn. The free mass or frequency compensation coupler can also be located inside an annular probe between the portion of the probe where the capturing member is located and the horn. Free mass  101  or frequency compensation coupler can also be located between the capturing member of the probe and the horn as shown in FIG. 5 b . One of ordinary skill in the art will note that other arrangements between the probe, the capturing member, the free mass and the horn can be envisioned. The present invention contemplates such envisioned arrangements. In addition, more than one frequency compensation coupler or free mass can be used. 
     Frequency compensation coupler  101  is made of a strong material, preferably metal, since it may be the weakest member of the ultrasonic probe assembly. The preferred materials are stainless steel, titanium, or other similar materials. However, one of ordinary skill in the art will readily appreciate that other materials may be used with this device. Frequency compensation coupler or free mass  101  reduces probe frequency from kHz to Hz. Thus, the frequency compensation coupler converts ultrasonic action into subsonic. This is desirable in some applications because the subsonic action creates less heat and performs better than an ultrasonic frequency. 
     FIG. 5 b  illustrates cross sectional view of a section of the ultrasonic floating tip with the free mass. In close up view of the proximal end of annular ultrasonic probe  11 , the tip of transducer  13  can be observed in relationship with the frequency compensation coupler or free mass  101 . The free mass is generally a metal disk but other materials can be used as long as strength is sufficient. The free mass is located between the tip of the transducer and the end of floating probe  11 . The function of the free mass  101  is to enhance the jack hammering effect of the ultrasonic drill/corer. 
     FIG. 6 shows different assemblies of the ultrasonic floating probe. In FIG. 6 a  a handheld assembly with a one-piece annular plastic probe  11  inserted into horn  64  is shown. It is possible to have a handheld assembly due to the relatively low axial preload required and because it is insensitive to alignment and can perform angle drilling and coring. The drilling or coring mechanism is the result of transverse and longitudinal motions such as hammering, which reduces the chances of having tip  119  jamming. Tip  119  of probe  11  doesn&#39;t have to be sharp and a diversity of tips can be design to the take advantage of this. FIG. 6 b  illustrated the same assembly except it also shows the frequency compensation coupler explained in FIG. 5 a . FIG. 6 c  shows the same handheld assembly with the addition of the frequency compensation coupler or free mass. If the hammering effect is to be enhanced without affecting the ultrasonic frequency, free mass  101  could be added to the assembly as shown in FIG. 6 d.    
     Furthermore, FIG. 6 e  depicts a two or multiple piece probe, while FIG. 6 f  depicts a one-piece probe. It should be noted that in the two or multiple piece construction, the pieces can be made of the same materials or can be made of varying materials such as stainless steel, titanium, plastic, or other suitable hardened material. It should also be noted that the one-piece construction could be made of plastic, stainless steel, titanium, or other suitable hardened material. 
     FIGS. 7A and 7B show a series of tip configurations that can be used on the ultrasonic floating probe according to the application. The tips could be constructed as closely spaced small diameter rods to allow chipping selected sections of the material being work on, or be smooth for slicing. Since the tip and the whole probe don&#39;t turn, drilling sensors can be added near the tip to examine the cored material. Potential sensors include temperature, eddy-current, acoustic sensors, dielectrics, fiber optics and others. Tip configurations  111  and  112  are shown which have a fingered construction for coring. The fingered configuration is particularly well suited for the coring of bones, one of the preferred uses of this ultrasonic assembly. It will be obvious to one of ordinary skill in the art that any type of tip configuration can be used with the present invention. 
     FIG. 8 shows a cross sectional view of the ultrasonic floating probe with irrigation and aspiration capabilities. The figure illustrates a free-floating annular probe or corer  11 . At the proximal end of free floating corer  11  there is an adapter  109  for irrigation. Adapter  109  has conduit  110 , which is connected to pump head  106 . Pump head  106  is part of pump  105 , which will pump irrigation fluid into corer  11 . The pump assembly has a number of tanks  108 , which will contain irrigation fluids such as saline. Each tank  108  has a conduit that goes to a series of solenoids  107  and then to main pump head  106 . There are two vacuum exits one for sampled cored  104  and another  102  for dust and volatile. These two sets of vacuum exits composed the aspiration unit. One of vacuum exits  102  is present in stepped horn  64  and the other at the back of the assembly, behind piezoelectric stacks  103 . 
     FIG. 9 illustrates the ease of use of the ultrasonic floating probe during drilling or coring. FIG. 9 shows hand  114  of the user and demonstrates the ease of holding the invention due to the low axial force required to produce the hammering or drilling action. The closed and lightweight handle  115  with the transducer, horn, etc can be appreciated on the figure. Floating probe  116  used for coring and/or drilling can be observed. Probe  116  can be of different lengths depending upon the application. 
     It is obvious to one skilled in the art that this invention, in any of the embodiments described above, can be used in many applications. A notable application of the subject invention is on bone grafts. The preparation of autogenous bone graft, allografts, or other substitutes such as corralline hydroxyapatite the present invention can be of use. 
     One of the steps in bone graft is the extraction of the material to be grafted. The use of the present invention with its coring and sample extraction mechanisms is especially adapted for this purpose. Another bone graft technique is the use of demineralized bone. Demineralized bone as used herein is defined as a cortical allograft bone wherein the removal of surface lipids and dehydration of the bone has been accomplished by diverse solutions such as ethanol or hydrochloric acid. The demineralization removes acid soluble proteins and leaves behind acid-insoluble protein, bone growth factors and collagen. The bone treated in this manner can be implanted in strips or processed into smaller particles. Also it has been suggested that if holes are drilled into cortical allograft it can increase the porosity of the bone by allowing a more efficient demineralization. This can result in a bone graft that it is more osteoconductive and osteoinductive. In all of these procedures the invention presented can be of great use. Another use for orthopedic drilling is on hip replacement where a hole must be drilled in the hip that is going to be replaced in preparation for the replacement. Bone marrow samples can also be obtained out of a person&#39;s healthy bone for typing or transplant in a less painful way that other procedures presented on the art. 
     Another orthopedic use is for the drilling/coring for insertion of pins or screws after an accident or disease to put together and repair the bone of a patient. 
     The transducer assembly can drill through different materials, including but not limited to, basalt, corsite, chalk, and ice. Uses in mining operations and sample taking on interplanetary explorations are notable applications of the present invention. 
     Although, for convenience, the method and resultant apparatus of the present invention has been described hereinabove primarily with respect to its preferred embodiments, it will be apparent to those skilled in the art that many variations of this invention can be made without departing from the spirit of the invention as claimed. The description presented in the preferred embodiments is not intended to demonstrate all of the possible arrangements and modifications to the design. For those skilled in the art, changes will be apparent that will fall within the spirit and the scope of the present invention.