WO2006078459A2

WO2006078459A2 - Medical devices with surface sensors, and methods of making and using the same

Info

Publication number: WO2006078459A2
Application number: PCT/US2006/000316
Authority: WO
Inventors: Michele Migliuolo; William Suh; Jennifer Rogers
Original assignee: Verimetra, Inc.
Priority date: 2005-01-14
Filing date: 2006-01-06
Publication date: 2006-07-27

Abstract

Medical devices for measuring at least one of temperature and ion concentrations of a contacted internal biological surface are disclosed. The medical devices may also be configured to monitor other physical, chemical, and physiological properties. Contact of the medical device with the internal biological surface may also be monitored with one or more contact sensors, according to certain embodiments, concurrently with the temperature, ion concentration, or both. Methods of making and using the medical devices are also provided.

Description

MEDICAL DEVICES WITH SURFACE SENSORS, AND METHODS OF MAKING

AND USING THE SAME

This application claims priority to U.S. Provisional Patent Application No. 60/643,605, filed January 14, 2005.

DESCRIPTION OF THE INVENTION

Field of the Invention

[001] The present disclosure relates to, among other things, medical devices that comprise conformal surface sensors for insertion into a human or animal body for medical treatment or for diagnostic purposes and methods for making and using the same. Examples of such devices include catheters, cannulas, guidewires, scopes (rigid or flexible endoscope, laparoscope, etc.), probes (rigid or flexible vaginal probe, rectal probe, urethral probe, oral probe, nasal probe, esophageal probe, percutaneous medical probe, etc.), osteotomic saws, and others. Examples of the conformal surface sensors, which can be used for measurements at or near a point of contact with an internal biological surface, include contact, force, temperature, ion specific concentration, and other sensors.

Background

[002] The measurement of physiological properties such as temperature and ion concentration at a surface of a tissue or organ with an inserted medical device is of interest for certain medical practices. For example, diagnosing vulnerable plaque within a vessel wall may require very accurate and sensitive temperature measurement with an inserted medical device very near to or at the contacted surface (such as catheter, guidewire, or probe). Measuring various ion concentrations at the contacted surface could also improve diagnosis information. Additionally, concurrently measuring both contact temperatures and ion concentrations could further improve diagnosis. For example, because the response of an ion sensor is typically a function of temperature, signals from the ion sensor (and other sensors) may need temperature-based correction, compensation, or scaling to provide an accurate ion concentration measurement. Various tissue ablation treatments (such as RF ablation, cryo ablation, etc.) also require fast and accurate temperature feedback from the contacted surface of ablated tissue in order to, for example, avoid accidental rupture of the ablating tissue due to overheating. Another example is a fast but accurate contact measurement of cervical wall temperature for determining ovulation status or anomalies at the cervical wall.

[003] However, due to their construction, current devices are not capable of measuring true temperature and ion concentrations at the contact surface between a measuring instrument and a tissue of interest, which may aid certain medical procedures, including those previously mentioned.

[004] Accordingly, a need exists for insertable medical devices with one or more surface sensors capable of measuring one or more physiological properties, such as temperature or ion concentration, at or near a point of contact with a tissue, organ, or other biological surface of interest. There also exists a need to separately or concurrently determine contact information, such as location or the extent of contact, with the surface of interest. There also exists a need to concurrently determine a tissue temperature, contact status, and ion concentrations at the contact surface. According to certain embodiments, there are provided possible configurations of such medical devices and methods of making and using the same, which would overcome one or more of the mentioned shortcomings.

SUMMARY

[005] The present disclosure is directed to medical devices and methods for measuring at least one property chosen from temperature and ion concentrations of an internal biological surface, such as one contacted with the disclosed device. According to certain embodiments, contact of the medical device with the internal biological surface may be monitored concurrently with the temperature, ion concentration, or both. According to certain embodiments, other physical, chemical, and physiological properties may also be monitored.

[006] The present disclosure also relates to medical devices for treating or diagnosing human or animal conditions, such as a medical device configured for insertion into a human or animal body. As used herein "configured for insertion into a human or animal body" is intended to mean that the medical device has been designed or is intended for use according to a medical application within a human or animal body. Examples of such devices include catheters, cannulas, guidewires, scopes (rigid or flexible endoscope, laparoscope, etc.), probes (rigid or flexible vaginal probe, rectal probe, urethral probe, oral probe, nasal probe, esophageal probe, percutaneous medical probe, etc.), osteotomic saws, and others.

[007] The medical device can have an outer contact surface configured for contacting an internal biological surface of the body. As used herein "configured for contacting an internal biological surface of the body" is intended to mean that the medical device has an outer surface that has been designed for or is intended for making contact with an internal biological surface according to a medical application. Such devices include, according to certain embodiments, devices where contact with the internal biological surface (tissue) is necessary to achieve a measurement of a tissue property or to perform a treatment or procedure on the contacted tissue. Such devices are not intended to necessarily include, according to all embodiments, medical devices where contact with an internal biological surface is an incidental consequence of the medical procedure, but is not the object or goal of the devices used according to the medical application.

[008] The outer contact surface of the medical device may have any contour, such as flat or curved, and may have, for example, a contour complementary to the intended internal biological contact surface. The outer contact surface can be, according to certain embodiments, located on a rigid or flexible member (such as, for example, a shaft, tube, rod, or sheet) of the medical device, where the rigid or flexible member is adapted for insertion in a human or animal body.

[009] According to certain embodiments, the medical device can further include at least one conformal surface sensor located at or near the medical device outer contact surface. The at least one conformal surface sensor can be chosen from, for example, a thermocouple and an ion sensor configured to measure temperature and ion concentration, respectively, of a contacted internal biological surface.

[010] As used herein a sensor "configured to measure" or "configured to monitor" a given property (e.g., temperature) or status (e.g., contact, position) is intended to mean a sensor that has the ability to measure, directly or indirectly, the given property or status. To be configured to measure or monitor a property or status does not require the sensor to be, in all uses or at all times, actively measuring or actively providing a reporting signal related to the given property or status. It need only be able to provide a signal or response, such as digitized data, voltage, current, or frequency, related to the measured or monitored property, such as its status (e.g., contact/non-contact) or magnitude (e.g., 120⁰C). Of course, a sensor may be configured, according to certain embodiments, to measure more than one property.

[011] According to certain embodiments, the present invention can further include at least one conformal contact sensor located at or near the outer contact surface. The at least one conformal contact sensor can be configured to monitor contact of the outer contact surface with the biological surface.

[012] According to certain embodiments, the present invention relates to a tissue ablation device (such as RF ablation, cryo ablation, etc.). The tissue ablation device can include an ablation tip configured for insertion into a human or animal body. The ablation tip can also have an outer contact surface configured for contacting an internal biological surface of the body.

[013] According to certain embodiments, a tissue ablation device can further include at least one conformal surface sensor located at or near the outer contact surface. The at least one conformal surface sensor can include a thermocouple configured to measure a temperature of an internal biological surface, such as one contacted by the medical device.

[014] According to certain embodiments, a tissue ablation device can include at least one conformal contact sensor located at or near the outer contact surface. The at least one conformal contact sensor can be configured to monitor contact between the outer contact surface and the internal biological surface.

[015] According to certain embodiments, a tissue ablation device can include both a conformal thermocouple configured to measure a temperature of a contacted internal biological surface and a conformal contact sensor configured to monitor contact between the outer contact surface and the internal biological surface.

[016] According to another embodiment, the medical device comprises an intra vaginal probe. In one embodiment, the intra-vaginal probe is a cervical probe, such as a cervical fertility probe, configured for intra vaginal insertion. Such a device may include an outer contact surface configured for contacting a cervical surface.

[017] According to certain embodiments, the cervical probe can further include at least one conformal surface sensor located at or near the outer contact surface. The at least one conformal surface sensor can include a thermocouple configured to measure a temperature of a contacted cervical surface. Alternatively or additionally, the at least one conformal surface can include an ion sensor configured to measure an ion concentration of the contacted cervical surface, or other nearby tissues or fluids.

[018] According to certain embodiments, the fertility probe can further include at least one conformal contact sensor located at or near the outer contact surface. The at least one conformal contact sensor can be configured to monitor contact between the outer contact surface and the contacted cervical surface.

[019] In another embodiment, the medical device comprises a medical saw, such as an osteotomic saw. The saw can include, according to certain embodiments, a plurality of cutting teeth and be configured for in vivo cutting of biological material.

[020] According to certain embodiments, the saw can further include at least one conformal surface sensor located at or near at least one of the cutting teeth. The at least one conformal sensor can include a thermocouple configured to measure a temperature at or near at least one cutting tooth.

[021] The present disclosure also relates to methods of making medical devices, such as probes and saws that include at least one conformal sensor. For instance, a method of making a medical device for treating or diagnosing human or animal conditions may include forming a medical device (which may include, for example, obtaining a pre-formed medical device) configured for insertion into a human or animal body. The medical device may have an outer contact surface configured for contacting an internal biological surface of the body. [022] The method may further include forming at least one conformai surface sensor at or near the medical device outer contact surface. The forming of the conformai sensor may include embedding the conformai surface sensors partially or entirely in and/or on the outer contact surface of the medical devices.

[023] The at least one conformai surface can be chosen from, for example, a thermocouple and an ion sensor. The at least one conformai sensor can be configured to measure at least one property chosen from, for example, temperature and ion concentration of an internal biological surface, such as one contacted by the medical devices. According to certain embodiments, the outer contact surface of the medical device serves as a substrate for the forming of the at least one conformai sensor. For example, forming at least one conformai surface sensor can include microfabricating, such as the fabricating techniques according to PCT/US04/02547, the at least one conformai sensor on the outer contact surface.

[024] The present disclosure also relates to methods of using medical devices, including device that have at least one conformai sensor. For instance, a method of use may include a diagnostic procedure, a treatment procedure, a monitoring procedure, or any combination thereof.

[025] For example, in one embodiment, there is disclosed a method of treating or diagnosing human or animal medical conditions that comprises inserting a medical device into a human or animal body. The method may include, for example, at least one device chosen from a tissue ablation device, a cervical fertility probe, and osteotomic saw, for performing the desired function (e.g., tissue ablation, fertility monitoring, and cutting). Such devices may have an outer contact surface configured for contacting an internal biological surface of the body, and at least one conformai surface sensor located at or near the medical device outer contact surface. The at least one conformai surface sensor can be chosen from, for example, a thermocouple and an ion sensor. The at least one conformai sensor can be configured to measure at least one property chosen from, for example, temperature and ion concentration of a contacted internal biological surface, tissue, or fluid. The method can further include inserting the medical device into the body, contacting the outer contact surface with the internal biological surface, and using a response from the at least one conformal sensor for treating or diagnosing the condition.

[026] In addition to the subject matter discussed above, the present disclosure includes a number of other exemplary features such as those explained hereinafter. It is to be understood that both the foregoing description and the following description are exemplary only.

BRIEF DESCRIPTION OF THE DRAWINGS

[027] Fig. 1 is a schematic representation of thermocouple sensing system, as used according to an embodiment of the present disclosure;

[028] Fig. 2 is a schematic representation of an ion sensing system, as used according to an embodiment of the present disclosure;

[029] Fig. 3A is front perspective view of an ablation tip with access hole locations for wiring, according to an embodiment of the present disclosure;

[030] Fig. 3B is top perspective view of an ablation tip with access hole locations for wiring, according to an embodiment of the present disclosure;

[031] Fig. 4A is an enlarged section^* of a wired access hole in front view, according to an embodiment of the present disclosure;

[032] Fig. 4B is an enlarged cross sectional view of a wired access hole, according to an embodiment of the present disclosure;

[033] Fig. 5A is a front perspective view of an ablation tip with four conformal surface thermocouples, according to an embodiment of the present disclosure;

[034] Fig. 5B is a top perspective view of an ablation tip with conformal thermocouples, according to an embodiment of the present disclosure;

[035] Fig. 5C is an enlarged cross sectional perspective of a conformal surface thermocouple, according to an embodiment of the present disclosure;

[036] Fig. 6A is a front perspective view of an ablation tip with conformal surface thermocouples and contact sensors, according to an embodiment of the present disclosure; [037] Fig. 6B is a front perspective view of an ablation tip with conformal surface thermocouples and contact sensors, according to an embodiment of the present disclosure;

[038] Fig. 7A is a front perspective of an ablation tip with an alternative conformal sensor configuration, according to an embodiment of the present disclosure;

[039] Fig. 7B is a side perspective of an ablation tip with an alternative conformal sensor configuration in contact with a tissue surface, according to an embodiment of the present disclosure;

[040] Fig. 8 is a calibration curve for a surface mounted conformal temperature sensor, according to an embodiment of the present disclosure;

[041] Fig. 9(A)-(E) are perspective views of a cervical probe with a conformal surface sensor, according to an embodiment of the present disclosure;

[042] Fig. 10(A)-(D) are perspective views of a cervical probe with an embedded conformal sensor, according to an embodiment of the present disclosure;

[043] Fig. 11A is a side view of a device with surface sensors, according to an embodiment of the present disclosure;

[044] Fig. 11 B is a side view of a device with surface sensors, according to an embodiment of the present disclosure;

[045] Fig. 12A is a side perspective of an osteotomic saw blade with conformal surface thermocouples, according to an embodiment of the present disclosure;

[046] Fig 12B is a side perspective of a kinetic probe with conformal surface thermocouples, according to an embodiment of the present disclosure; and

[047] Fig. 12C is a side perspective of a catheter with conformal surface thermocouples, according to an embodiment of the present disclosure.

DESCRIPTION OF THE CERTAIN EMBODIMENTS OF THE INVENTION

[048] According to certain embodiments of the present invention, one or more surface sensors (e.g, thermocouples, ion sensors, contact sensors) can be conformally formed on an outer contact surface of a medical device. The device with the conformed sensor can be configured to make contact with an internal biological surface of interest. Such conformal sensors may be used to obtain more accurate measurements (such as temperature or ion concentration) of a contacted surface as compared with sensors and devices not configured for contact measurement of surface properties.

[049] For example, the biological surface (e.g., tissue or organ) may have a certain surface contour. The medical devices, or at least a part of the device, may be shaped to accommodate such contour for suitable contact, such as shaped complementary to the biological surface. For instance, if the biological surface has a concave outer surface the medical device surface may be convex. Having the thermocouple or other surface sensor follow such contour over the contact portion of the medical device would enhance or maximize intimate contact of the sensor with the tissue, and thereby provide more accurate measurements of the surface properties.

[050] For example, a thermocouple junction can be distributed over a specified area of the medical device outer surface. By doing so, the thermocouple may be also designed to cover an area on the device intended for contact with a biological surface. This allows measurement of an average temperature over the contacted biological surface.

[051] As used herein, a "conformal" sensor is a sensor that is formed onto and takes the shape of the underlying medical device where the underlying device serves as a substrate for the formation of some or all the features of the sensor, and the sensor conforms to a surface profile of the medical device. A conformal sensor in this context is distinct from a rigid sensor, such as a rigid thermocouple probe affixed to the underlying device after the thermocouple is fully formed separately from the underlying device. However, a sensor that is formed separately on a flexible substrate that can be conformed to the profile of the surface is considered one type of a conformal sensor.

[052] As used herein, a sensor to be located "at or near" a contact surface includes sensors located both on and within (wholly or partially) the region of contact between the medical device's outer contact surface and the biological surface, as well as sensors located near the medical device outer contact surface or the region of contact. Functionally, a sensor located "at or near" a contact surface will be able to preferentially monitor a property (e.g., temperature or ion concentration) of the contacted biological surface over that of bulk (e.g., surrounding fluid) away from the surface. It is also understood that as a device is positioned and or repositioned in the body, a sensor's status may change from being inside or outside the contact area, and that such a change does not affect the understanding that a sensor is configured to be "at or near" the contact surface.

[053] Thus, according to certain embodiments, the conformal sensor, such as a conformal thermocouple or ion sensor, will be on or in an outer surface of the medical device so that it can have direct contact with the contacted biological surface. For example, according to certain embodiments, one or more sensors may have their active sensing region located, during use of the medical device to contact an interior biological surface, within the contact area between the medical device and the biological surface.

[054] As another example, according to certain embodiments the conformal sensor, such as a conformal thermocouple, may be located within an underside of a contact surface, so long as the measured parameter (e.g., temperature) can be accurately measured by the conformal sensor. For example, a thermocouple may be located on a non-contact area (such as a protected underside) of a thermally conductive probe tip.

[055] As another example, according to certain embodiments, one or more sensors may have at least part of their active sensing surface located away from but near to the contact area between the medical device and the biological surface, such that the sensor is close enough to the contact area to preferentially monitor a property at the contacted surface. For example, according to certain embodiments, an ion sensor may be within a 5mm range, a 2.5mm range, or, as another example, a less than 1mm range of the contact area and still be considered "at or near" according to certain embodiments. As another example, a temperature sensor may be within a 5mm range of the contact area and still be considered "at or near" according to certain embodiments. [056] According to certain embodiments of the present invention, one or more thermocouples may be beneficially used as temperature sensors for devices that will make contact with a surface for measurement of that surface. Specifically, one or more thermocouples may be used for contact temperature measurements over other temperature sensors to avoid interference effects caused by contact. For example, a conformal surface temperature sensor using highly thermoresistive materials that are commonly used for making RTDs (i.e., resistance temperature detectors) and thermistors can be prepared as disclosed in US patent application "Medical and Surgical Devices with Integrated Sensors", No. PCT/US04/02547, filed January 30, 2004, the entirety of which is hereby incorporated by reference. However, when such a thermoresistive sensor on the surface of a device makes contact with a surface (e.g., biological tissue), its resistance changes not only due to temperature of the surface but also due to stress caused by contact. This stress-induced resistance change interferes with the true surface temperature measurement. Thus, use of minimally thermoresistive and minimally stress sensitive materials that are temperature sensitive can be beneficial, according to certain embodiments, for measuring temperature of contacted surface.

[057] A schematic representation of a thermocouple system is shown in Fig. 1. As known in the relevant art, thermocouples are voltage generation sensors formed by two dissimilar metals (102, 104), with respectively different Seebeck coefficients (i.e., the derivative of thermal EMF with respect to temperature, which can be expressed in units of millivolts per degree) that are overlapped (106). Voltage generation from a thermocouple is an integral of the difference in Seebeck coefficient over the temperature difference between the reference and the overlapping area. Thus, the temperature sensitive output, that is the voltage, is a strong function of Seebeck coefficients and temperature but is a negligible function of resistance and contact stress.

[058] Suitable materials for forming thermocouple include, for example, aluminum, antimony, bismuth, carbon, constantan, copper, germanium, gold, iron, nichrome, platinum, potassium, rhodium, selenium, silicon, silver, sodium, tantalum, tellurium, tungsten, etc. For example, a simple thermocouple can be formed by an overlapping region of constantan and copper, which have Seebeck coefficients of -35 and 6.5, respectively. This makes a typical T-type thermocouple that is commonly used in industry. Biocompatible metals, such as gold and platinum, can also be used to make a biocompatible thermocouple. Selection of appropriate thermocouple materials can also be based on consideration of their Seebeck coefficient as well as processing required for the material deposition. Further information on thermocouples, their formation, use, materials, theory, and circuitry may be found in, for example, Temperature Measurement in Engineering, Vol. 1 and 2, Baker, H.D., John Wiley & Sons, Inc., New York, 1953-1961 , which is incorporated herein by reference.

[059] According to certain embodiments, the conformal thermocouple can be formed by a thin-film deposition technique so that its thickness is very thin (on the order of a micron or less). This makes its thermal inertia very small despite the fact that its width and length may cover the area that is many orders of magnitude greater than its own thickness. Thus, for many cases, small variations of temperature over thermocouple area can be instantly averaged. Certainly, the coverage area of the conformal thermocouple may be adjusted, for example to make area averaged temperature measurement or point measurement, based on the needs of a specific application. Also, a plurality of conformal thermocouples may be formed on the medical devices for obtaining temperature gradients or distributions over a specified region.

[060] According to certain embodiments of the present invention, there is at least one conformal ion sensor integrated onto or into an outer contact surface of an insertable medical device. A schematic representation of an exemplary ion sensing system is shown in Fig. 2. Measuring pH or other ion concentrations at the contact surface can be used as an indicator of anomalies such as tumor or vulnerable plaque. Such sensors can be made by, for example, similar thin-film processing described herein for making the conformal surface thermocouples.

[061] Conformal ion sensors can be used for detecting any of a variety of individual or groups of ions, such as hydrogen, sodium, potassium, ammonium, calcium, chloride, magnesium, and nitrate. Non-limiting examples of metal oxides such as PtO2, IrO₂, RuO₂, TiO₂, RhO₂, etc. may be used as pH electrodes that detect hydrogen ion concentration. For example, iridium oxide, IrOx, electrodes have received considerable attention due to this material's known stability over a wide pH range.

[062] As known in the art, such metal oxides may be deposited by using a sputtering system. Thus, according to certain embodiments, similar to fabrication methods for the conformal thermocouples herein, a miniature conformal ion sensor can be fabricated onto a small area of an insertable medical device whose surface is stainless steel, platinum, or other suitable material. According to certain embodiments, the conformal ion sensor can be protected above or below with a protection layer. The protection layer may, for example, comprise NAFION®, a microporous polyester membrane, or any combination thereof.

[063] According to certain embodiments, a silver/silver chloride electrode or other reference source can be utilized as reference electrode 208 (Fig. 2) for the conformal ion sensor. The sensor's performance parameters such as sensor potential, drift, redox interference, etc. can be controlled by the sputtering conditions such as oxygen partial pressure, argon pressure, humidity, substrate temperature, deposition rate, electrical field, etc.

[064] The Nernst equation describes that the electrical potential difference at the ion sensitive interface (sensing electrode 206), located according to certain embodiments at the device surface, is a linear function of the change of the ion activity (in logarithmic units) and is also linear function of temperature. Thus, it may be beneficial according to certain embodiments to measure temperature while measuring the potential difference caused by ion concentration in order to compensate for any offset or drift due to temperature. According to certain embodiments, the reference electrode 208 is either protected within an insertable medical device or is external to the device.

[065] Further information on ion sensors, their formation, use, materials, theory, and circuitry may be found in, for example, Ion Selective Electrodes in Analytical Chemistry, Vol. 1 and 2, H. Freiser, Plenum Press, 1978-1980, which is incorporated herein by reference.

[066] According to certain embodiments, a conformal surface contact sensor may be provided to complement an insertable medical device. For example, since the accuracies of measurements of an internal biological surface may depend on the location or quality of contact (e.g., partial or full contact) of the device with the surface, a conformal surface contact sensor may be used to, for example, monitor the contact of the medical device with the biological surface. According to certain embodiments, concurrent monitoring of contact status with surface temperature and/or surface ion concentrations would realize a particularly beneficial surface sensing medical device as a whole.

[067] As used herein, "concurrent," as in "concurrent monitoring," encompasses both simultaneous and sequential measurements of the concurrently monitored properties. Thus, for example, "concurrent monitoring" would include first monitoring a contact sensor to determine an initial contact status and then sequentially monitoring a temperature sensor during the procedure. As another example, "concurrent monitoring" would include monitoring both a contact sensor and a temperature sensor simultaneously. Further, according to certain embodiments, "concurrent monitoring" does not require that equal time be devoted to each of the concurrently monitored properties, although according to some embodiments equal monitoring time may be devoted to some or all concurrently monitored signals.

[068] According to certain embodiments, a conformal surface contact sensor can be formed from, for example, multiple conductive electrodes. A known voltage can then be applied between the conductive electrodes using tissues and body fluids as a conducting path between the electrodes. As one example, current flow between the conductive electrodes can be monitored as a contact indicator based on impedance characteristics of targeted tissues and its surrounding. Knowing an approximate impedance or conductivity of both targeted tissue and surrounding body fluid (or gas) per a given application, a proper contact condition with the tissue can be found based on the current flow. Additionally or alternatively, contact or its absence may be indicated by sudden increases or decreases in average current flow. These sudden changes may be due to rapid changes of the circuit impedance with changes in contact. Contact detection is enhanced if the difference between conductivity of the tissue and the surrounding fluid is large. Various modulation schemes can be utilized to give different voltage inputs based on a specific requirement of certain applications. [069] According to certain embodiments, a conformal contact sensor can comprise an ultrasonic sensor. Such a contact sensor can detect or monitor differences of acoustic impedance between, for example, a target tissue surface and the surrounding bodily fluid (or gas). The ultrasonic contact sensor may measure, for example, various properties of a reflected acoustic wave. The property may be chosen from, for example, amplitude, phase, time delay, and any combination thereof. The ultrasonic contact sensor may also be used, in certain applications, to generally characterize the contacted tissue based on its acoustic impedance properties.

[070] An ultrasonic contact sensor may comprise at least one ultrasonic element. One such ultrasonic element may be used as both a transmitter and a receiver. Separate transmitters and receivers may also be used. The ultrasonic elements may be formed as conformal sensor elements according to the microfabricating and deposition methods discussed elsewhere herein.

[071] Locations of the contact sensors can be chosen such that they are most likely to contact the tissue of interest but would not interfere with operation of other sensors or functional components of the medical device. According to certain embodiments, multiple contact sensors may be employed to determine which part of a device makes contact with a surface. This may include, for example, using multiple contact sensors to determine which part or parts of the contact sensor is making contact at a given time during a medical procedure. In a certain embodiment, thermocouples themselves may be used as contact sensors by using a relay in the control circuitry. The relay circuit can act as a switching element between a temperature detection circuit and an impedance monitoring circuit at a specified switching frequency.

[072] Further information on contact surface sensors, their formation, use, materials, theory, and circuitry may be found in, for example, Advance Tactile Sensing for Robotics, H. Nicholls, World Scientific Publishing Company 1992, which is incorporated herein by reference.

[073] The present invention also relates, according to certain embodiments, to methods of making devices and sensors. According to a certain embodiment, a surface of an insertable medical device serves as a substrate onto which sensors are deposited. For example, in one embodiment, the surface may be an outer surface or an inner surface of a medical device component. Additionally, the substrate may be a flexible material, such as those used in flex- circuitry. Such materials include, for example, MYLAR^®, KAPTON ^®, and PI^®. The flexible substrate having elements of the sensor may then be conformed to the medical device surface.

[074] According to certain embodiments, a plurality of cavities such as holes, slots, grooves, etc. may need to be formed in a selected surface of the device. These can be accomplished by techniques known in the art such as mechanical drilling, boring, laser ablation, EDM, and photochemical etching. These cavities may be used as, among other things, wiring routes. Also, by matching the depth of a cavity and the thickness of the sensor and other coatings, a shallow cavity underneath a sensor allows the host device to maintain uniform topography even after forming sensors and protective coatings.

[075] Depositions of one or more sensor materials may be realized by various physical and/or chemical deposition techniques. These include, for example, spin casting, casting, stamping, molding, sputtering, thermal evaporation, PECVD, LPCVD, MOCVD, and Pulsed Laser Deposition (PLD), electroplating, electroless plating, and sol-gel.

[076] The same deposition techniques may be used for creating insulation coatings that form part of certain sensors, such as between metal substrates and the sensors, if necessary. For example, a thin insulation coating such as parylene may be used. A protective coating may also be applied over the sensors if necessary. For example, controlled dipping into a biocompatible UV curable epoxy creates a durable protective coating. The choices of insulation and protection material and their deposition methods will depend upon, for example, the requirements imposed by the type of insertable medical device, intended medical application, cost, reliability, etc. According to certain embodiments, if the substrate contains a low melting point material, such as PEBAX® coating on the outer wall of a catheter, a protective coating such as parylene can be very useful due to its low deposition temperature.

[077] More details on making conformal sensors are provided in "Medical and Surgical Devices with an Integrated Sensor", PCT/US04/02547, which is incorporated herein by reference.

[078] Medical tissue ablation is a minimally invasive procedure that involves placing an ablating member into or onto a target tissue and heating the tissue (e.g., cardiac tissue or tumor tissue) by Joule heating from an RF power source or alternatively freezing the tissue by cold liquid (e.g., liquid nitrogen) circulating within the member. For example, RF ablation has been used to treat cardiac arrhythmia, liver cancer, lung cancers, and other tumor treatments. During RF ablation, accurate and fast temperature feedback from the ablating surface is one indicator of how well the RF ablation is being performed at the contact tissue. The burst of RF energy may be rapid and may quickly and strongly locally heat the contact tissue. In order to avoid excessive heating, which may lead to unwanted premature tissue damage, it is desired to measure temperature at the contact surface. RF ablation and RF ablation tips for medical applications are generally disclosed in Ten Years of Radio Frequency Catheter Ablation, Jeronimo Farre, Futura Publishing, 1998, incorporated herein by reference. Other ablation methods that may be used consistent with certain embodiments of the present invention including cryo ablation.

[079] A surface thermocouple (with its thickness in the order of, for example, a micron or less) as described herein can measure temperature at the contact surface very quickly due to its small thermal inertia. Conformal construction of the thermocouple can enhance contact with the tissue, especially (though not necessarily, according to all embodiments) when a contact sensor is also used. This allows very accurate temperature measurement right over the area of contact surface, not just a point contact. For example, for an ablation tip having a left side and a right side, use of a thermocouple/contact sensor pair on each side can enable a determination of which side is making contact and hence which thermocouple to monitor for measuring a surface temperature. The use of contact sensor can also provide useful information that may be used to guide or adjust a position of the device within the body. Additional pairs of sensors can further provide additional information concerning contact and surface property measurements. In contrast, conventionally, the temperature of a RF ablation tip is monitored with a thermocouple that is either embedded inside the tip or located outside the tip as a thermocouple junction, but not as a conformal surface member.

[080] The invention will be further clarified by the following non-limiting examples, which are intended to be purely exemplary of the invention.

[081] Example 1

[082] This Example relates to the formation of a medical device comprising an RF ablation tip. As represented in Figs. 3-5, conformal surface thermocouples were integrated onto the surface of an experimental RF ablation tip. Several surface thermocouples were formed on the outer surface 310 of a metallic RF ablation tip, which was a cylindrically shaped metal shaft, approximately 2mm in diameter and 8mm in length. Figs. 3 and 4 show holes 312 used for wiring in order to make contacts between constantan (or copper) wire and constantan (or copper) sensor layer of the conformal thermocouples on outer surface 310 to internal cavity 390 and wiring 340. Insulation (Teflon) 452 coated constantan (or copper) wires 454 were inserted through the holes 312, insulating epoxy 456 was then applied to fill the holes up to the level of the outer surface 310 of the tip and was cured. Fig. 4A and B show a close-up view for area A1 of such arrangement. Fig. 4A shows a top view of the wired hole 312 and Fig. 4B shows a cross section of the wired hole along line L1. Conceptually, the idea was to hold the wire in place while preventing any electrical shortage between the wires 454 and the metallic tip 310. A parylene coating 458 was deposited over a portion of tip 310 as an insulation layer where the sensors would form. Depending on the substrate and the application, the insulating layer could be electrically insulating, thermally insulating, or both. The overlapping 506 constantan 502 and copper 504 layers, as shown in Fig. 5A-C, were then deposited through respective mask openings using a DC sputtering system (Model SC2000, Vacuum Process Technologies, Plymouth MA) with processing conditions of 4OmT, 200W for 45min.

[083] Parylene was coated over the surface temperature sensor as a protection layer 560 using a parylene deposition system (Model 2010 LABCOTER, SCS, Inc). Parylene dimer C is a powder form of parylene that is consumed by the parylene deposition system. Approximately 10 grams of the dimer were used to deposit approximately 6 micron-thick parylene coating onto the surface of the thermocouple.

[084] Fig. 8 shows a temperature calibration plot for the surface mounted conformal thermocouple prepared as described above. This device was formed on the outer surface of an experimental RF ablation tip. Calibration entailed monitoring the sensor response in a heated water bath as compared with a commercial thermocouple (Omega, model SC-TT-T-20-36) in the same bath. As shown in Fig. 8, excellent linearity and correlation with true temperature was found.

[085] Fig. 6 shows a possible configuration of a RF ablation device having multiple sensors. Contact sensors 631-634 on outer tip surface 610 could provide contact status while thermocouples 635, 636 measure temperature at the same time. Sensors can be connected into the internal cavity 690 to wires 640 and then to control electronics, such as those according to Figs. 1 and 2. The obtained data would be verifiable due to the correlation between contact temperature and contact quality. Fig. 7 also shows another possible alternative configuration for measuring temperature distribution along the ablation tip with outer surface 710 when the tip is configured to be used vertically with respect to tissue. It is apparent that many different variations are possible without departing from the scope of this invention.

[086] Example 2

[087] This example relates to the formation of a cervical fertility probe. Cervical fertility probes and their medical uses are generally described in U.S. Patent No. 4,530,366, Electronic Instrument for the Control and Treatment of Infertility in Women, Nessi, et al., which is incorporated herein by reference. Several surface thermocouples were fabricated onto an experimental fertility probe. The fertility probe can be used to monitor cervical temperature in order to accurately determine ovulation period. Conventionally a thermocouple or thermistor is located inside of the probe to measure temperature. However, since accurate cervical temperature can be measured at the surface of cervix, a potentially more accurate and faster method to monitor cervical temperature is to have the surface temperature sensors in contact with the cervical surfaces as generally explained above and in example 1.

[088] A fabrication method similar to that of example 1 was used to realize the sensor. Various holes and grooves were made onto metal pieces configured to contact the cervical wall. These holes and grooves were made to accommodate thermocouple wiring as before.

[089] Fig. 9 shows a configuration where a thermocouple 931 is located on an outer contact surface of the metal probe tip for the fastest response time. Fig. 9A is a sectional view of probe tip 910 along line L3 in Fig. 9B, which is a bottom side view of probe tip 910 showing wiring channel 920 and holes 912. As depicted, the face of Fig. 9B corresponds to the flat inside surface 950 of the tip, as also shown in Fig. 9D. Fig. 9C shows a top side view of probe tip 910 with holes 912. Fig. 9D is a sectional view of probe tip 910 along line L4 in Fig. 9C. Fig. 9E shows a side perspective view of probe tip 910 with surface sensor 931 connected to cervical probe 970. Wiring 940 connects from the probe tip 910 inside cervical probe 970 to control electronics (not shown). In addition to or instead of features such as an electrically insulating layer below the thermocouple electrodes (e.g., Fig. 4, layer 458), it would be possible to provide a thermally insulating layer between the thermocouple and the probe tip. This could further enhance response time by limiting the influence of the probe tip's thermal mass on the thermocouple.

[090] Figs. 10A-D show a configuration where a thermocouple 1035 is located inside of the metal tip 1010 for its maximum protection. According to this embodiment, the metal tip 1010 acts as heat conduction member for the thermocouple 1035. Fig. 10A is a sectional view of probe tip along line L5 in 10B. Wiring channels 1020 are shown filed in Fig. 10B with overlapped 1006 thermocouple material 1002, 1004 forming thermocouple 1035. Fig. 10B shows the lower inside face of metallic tip 1010. Fig. 10C and 10D show two perspective views of the tip 1010 attached to probe 1070.

[091] Again, it is apparent that many different variations are possible without departing from the scope of this invention. For example, Fig. 11 shows some other possible variations of sensors, such as surface thermocouples 1135, within the scope of certain embodiments of the present invention.

[092] Example 3

[093] Other potential applications of embodiments of the disclosed medical device would include temperature sensing for an osteotomic saw near its cutting teeth as shown in Fig. 12A. Osteotomic saws and their medical uses are generally described in U.S. Patent No. 4,985,031, Buss et al., incorporated herein by reference.

[094] A modern osteotomic automatic saw could create necrosis under high speed, high torque, or high stress operation. Having surface thermocouples that are relatively insensitive to shear stress near the cutting teeth would allow detection of accurate temperatures right at the cutting surface, which could be feedback to a speed controller of the saw. In certain embodiments, the saw material itself may serve as the first thermocouple material while the second thermocouple material would form individual sensing elements near the cutting teeth. Traces of the second thermocouple material over the insulation material could serve as conducting wires. Also, the temperature distribution along the device could be obtainable by varying the number, size and location of these surface sensors. Additional embodiments of devices within the scope of the present invention are shown in Figs. 12B,C, respectively showing a kinetic probe (closed end catheter) and an open lumen catheter.

[095] Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and following claims are approximations that may vary depending upon the desired properties sought to be obtained.

[096] While various embodiments of the present invention have been illustrated, those embodiments have been presented by way of examples and are not intended to limit the scope of the present invention. Those of skill in the art will appreciate that various additions, deletions, modifications and other changes maybe made without departing from the intended spirit and scope of the present invention.

Claims

What is claimed is:

1. A medical device for treating or diagnosing human or animal conditions, comprising: a medical device configured for insertion into a human or animal body, the medical device comprising an outer contact surface configured for contacting an internal biological surface of the body; and at least one conformal surface sensor located at or near the outer contact surface, wherein the at least one conformal surface sensor is chosen from a conformal thermocouple and an ion sensor and is configured to measure at least one of temperature and ion concentration of the contacted internal biological surface.

2. A medical device for treating or diagnosing human or animal conditions, comprising: a medical device configured for insertion into a human or animal body, the medical device comprising an outer contact surface configured for contacting an internal biological surface of the body; at least one conformal surface sensor located at or near the outer contact surface, wherein the at least one conformal surface sensor is chosen from a thermocouple and an ion sensor and is configured to measure at least one of temperature and ion concentration of the contacted internal biological surface; and at least one conformal contact sensor located at or near the outer contact surface, wherein the at least one conformal contact sensor is configured to monitor contact of the outer contact surface with the contacted internal biological surface.

3. A tissue ablation device, comprising: an ablation tip configured for insertion into a human or animal body comprising an outer contact surface configured for contacting an internal biological surface of the body; at least one conformal surface sensor located at or near the outer contact surface, the at least one conformal sensor comprising a thermocouple configured to measure a temperature of the contacted internal biological surface; and at least one conformal contact sensor located at or near the outer contact surface, wherein the at least one conformal contact sensor is configured to monitor contact of the outer contact surface with the contacted internal biological surface.

4. A tissue ablation device according to claim 3, wherein the ablation tip comprises at least one of an RF ablation tip and a cryo ablation tip.

5. A cervical fertility probe, comprising: a cervical fertility probe configured for intra vaginal insertion, the cervical fertility probe comprising an outer contact surface configured for contacting a cervical surface; at least one conformal surface sensor located at or near the outer contact surface, wherein the at least one conformal surface sensor is chosen from a thermocouple and an ion sensor and is configured to measure at least one of temperature and ion concentration of the contacted cervical surface; and at least one conformal contact sensor located at or near the outer contact surface, wherein the at least one conformal contact sensor is configured to monitor contact of the outer contact surface with the contacted cervical surface.

6. A medical device comprising: an elongated member having at least one surface having a plurality of cutting teeth configured for in vivo cutting of biological material; and a conformal surface sensor located on or near at least one of the cutting teeth, the conformal sensor comprising a thermocouple configured to measure a temperature at or near the at least one cutting tooth.

7. A medical procedure, comprising: inserting a medical device into a human or animal body, the medical device comprising an outer contact surface configured for contacting an internal biological surface of the body, and at least one conformal surface sensor located at or near the medical device outer contact surface, wherein the at least one conformal surface sensor is chosen from a thermocouple and an ion sensor and is configured to measure at least one of temperature and ion concentration of the contacted internal biological surface; contacting the outer contact surface with an internal biological surface; and monitoring a response from the at least one conformal sensor.

8. A procedure according to claim 7, further comprising at least one of ablation, cervical fertility probing, and osteotomic sawing.

9. A method of making a medical device for insertion into a human or animal body, the method comprising: forming a medical device configured for insertion into a human or animal body, the medical device comprising an outer contact surface configured for contacting an internal biological surface of the body; and forming at least one conformal surface sensor at or near the medical device outer contact surface, wherein the at least one conformal surface sensor is chosen from a thermocouple and an ion sensor and is configured to measure at least one of temperature and ion concentration of the contacted internal biological surface.

10. A method according to claim 9, wherein the outer contact surface serves as a substrate for the forming of the at least one conformal sensor, and forming the conformal surface sensor comprises microfabricating the conformal sensor on the substrate.

11.A medical device according to claim 1 , further comprising a conformal contact sensor located at or near the outer contact surface, wherein the conformal contact sensor is configured to monitor contact of the outer contact surface with the contacted internal biological surface.

12.A medical device according to claim 1 , wherein the at least one conformal surface sensor comprises a thermocouple configured to measure a temperature of the contacted internal biological surface and an ion sensor configured to measure an ion concentration of the contacted internal biological surface.

13. A medical device according to claim 1 , wherein the biological surface is chosen from a bone, cervix, and an ablation target surface.

14. A medical device according to claim 1 , wherein the medical device comprises at least one of a catheter, cannula, guidewire, scope, probe, and saw.

15.A medical device according to claim 1 , wherein the medical device comprises a catheter having the outer contact surface, the outer contact surface is a curved surface, and the at least one conformal sensor is a microfabricated sensor at least partially formed on the curved outer surface substrate.

16. A medical device according to claim 1 , wherein the at least one conformal surface sensor comprises a conformal thermocouple comprising at least two different materials having different Seebeck coefficients, and the conformal thermocouple occupies a portion of the outer contact surface and conforms to the portion of the outer contact surface.

17. A medical device according to claim 16, wherein the conformal thermocouple is formed by at least one deposition technique chosen from spin casting, casting, stamping, molding, sputtering, thermal evaporation, PECVD, LPCVD, MOCVD, and Pulsed Laser Deposition (PLD), electroless plating, electroplating, and sol-gel.

18. A medical device according to claim 1 , wherein the at least one conformal sensor comprises at least one conformal ion sensor.

19. A medical device according to claim 18, wherein the conformal ion sensor comprises metal oxide materials.

20. A medical device according to claim 18, wherein the conformal ion sensor is formed by at least one deposition technique chosen from spin casting, casting, stamping, molding, sputtering, thermal evaporation, PECVD, LPCVD, MOCVD, and Pulsed Laser Deposition (PLD), electroless plating, electroplating, and sol-gel.

21. A medical device according to claim 18, wherein the conformal ion sensor occupies a portion of the outer contact surface and conforms to the portion of the outer contact surface.

22.A medical device according to claim 18, wherein the conformal ion sensor comprises at least one of an ionophoric and an ion-exchange membrane.

23.A medical device according to claim 2, wherein the at least one conformal contact sensor comprises conductive electrodes.

24.A medical device according to claim 2, wherein the at least one conformal contact sensor comprises an ultrasonic sensor.

25.A medical device according to claim 2, wherein the at least one conformal contact sensor is formed by at least one deposition technique chosen from spin casting, casting, stamping, molding, sputtering, thermal evaporation, PECVD, LPCVD, MOCVD, and Pulsed Laser Deposition (PLD), electroplating, electroless plating, and sol-gel.

26.A medical device according to claim 2, wherein the at least one conformal contact sensor occupies a portion of the outer contact surface and conforms to the portion of the outer contact surface.

27.A medical device according to claim 2, wherein the at least one conformal contact sensor comprises at least two laterally separated conductive pads, and the conformal contact sensor is configured to monitor a surface contact status by measuring circuit impedance between the at least two conductive pads.

28.A medical device according to claim 2, wherein the medical device comprises a conformal thermocouple, a conformal ion sensor, and a conformal contact sensor; and the medical device is configured for concurrent monitoring of a contact status of the outer contact surface with the contacted internal biological surface, temperature of the contacted internal biological surface, and ion concentration at the contacted internal biological surface.

29.A medical device according to claim 28, further comprising control electronics configured to at least one of measure voltages generated from the conformal thermocouple, apply constant voltage or current to the conformal ion sensor, and monitor its change, apply constant voltage or current to the conformal contact sensor and monitor its change, control switching of applied or measure signals among the conformal thermocouple, the conformal ion sensor, and the conformal contact sensor, and adjust circuit parameters for conformal ion sensors according to at least one of measured contact status and measured temperature.