WO2015097251A2

WO2015097251A2 - Vibrating medical device for minimally invasive procedures

Info

Publication number: WO2015097251A2
Application number: PCT/EP2014/079250
Authority: WO
Inventors: Eric Chevalier
Original assignee: Eric Chevalier
Priority date: 2013-12-23
Filing date: 2014-12-23
Publication date: 2015-07-02
Also published as: WO2015097255A3; WO2015097255A2; WO2015097251A3

Abstract

A catheter type device comprising: an optical conductor (1) with a proximal end and a distal end and configured to conduct optical waves;and a material (2) configured to transform the optical waves conducted by the optical conductor (1) into mechanical waves.

Description

VIBRATING MEDICAL DEVICE FOR MINIMALLY INVASIVE

PROCEDURES

Field of the invention

[0001] The present invention relates to a method and device for minimally invasive procedures, and more specifically, it relates to the diagnosis, or cleaning, or removal of blockages in tubular tissues and organs.

[0002] Furthermore, the present invention relates to the ablation treatment in tubular tissues and organs.

Description of related art

Endodontic treatment [0003] Generally, the endodontic treatment comprises the steps of opening the carious cavity, cutting the enamel caries, removing the coronal pulp, enlarging the root canal orifice, exploring the root canal, extracting the radicular pulp, enlarging the root canal, and filling the root canal.

Normally, numerous probe instruments will be employed to perform this treatment method, including cleansers, reamers, files, and filling tools.

[0004] Generally, for removing the coronal pulp and other debris the dentist uses hand files or a handpiece with ultrasound actuator. The drawback of the latter is the loss of ultrasound energy along the file requiring an overdimensioned actuator and power. [0005] Moreover, a time-consuming and difficult step in the root canal operation has involved determining the depth of penetration of a reamer or file and precisely controlling and limiting the depth of such reamer or file so as not to penetrate either beyond the root apex or short thereof. One previous method of measuring the root canal length involved the insertion of a thin, flexible probe or explorer into the canal and performing x-ray of the carious tooth in order to determine the depth of penetration of the probe into the canal. Once the accurate measurement had been taken, successively used tools could be set to the proper penetration depth determined by the dentist. [0006] It would be therefore desirable to offer to a dentist a unique platform to perform a plurality of operations (diagnostic and/or treatment).

Treatment of chronic total occlusions calcified or fibrous plaques

[0007] Atherosclerosis is an intimal lesion that effects large and medium sized muscular arteries (such as coronary, iliac and femoral) and also large elastic arteries (such as aorta). It is a gradual chronic cardiovascular disease and is the most common cause of acute myocardial.

[0008] This disease begins with deposits of fatty substances

lipoproteins), cholesterol and cellular waste on the arterial endothelium but may progress to a fibro-calcific plaque. The majority of atherosclerotic lesions can be treated by minimally invasive dilation procedures such as balloon angioplasty and stent implantation. These procedures often require that the lesion is initially crossed by a guidewire, a thin wire that acts as a rail for the dilation catheter. Plaques resulting in a near or totally occluded artery are known as chronic total occlusions (CTOs) and are often associated with dense calcifications. They can be identified in approximately 20% of all patients undergoing angioplasty and are challenging to classic dilation procedures that require prior guidewire crossing.

[0009] The limitations of standard dilation procedures mentioned have propagated an intensive search for adjuncts to balloon angioplasty and alternative therapies.

[0010] One such approach involves the use of low frequency (20- 45 kHz) high power therapeutic ultrasonic energy delivered via small diameter wire waveguides. This form of energy develops a longitudinal standing wave in the wire waveguide and can result in distal-tip displacements up to 210μηη peak - peak (p-p).

[0011] Among these treatments is ultrasound angioplasty whereby a microcatheter is directed to the site of an occlusion. An ultrasonic

transducer is coupled to a transmission medium that passes within the catheter and transmits vibrations to a working tip at the distal end in close proximity to the occlusion. Ultrasonic catheters for dissolving

atherosclerotic plaque and for facilitating clot lysis have been described previously. Improvements on these inventions have concentrated on improving the operation or function of the same basic device (US Patent No. 5,397,301 ). The vibrations coupled into the tissues help to dissolve or emulsify the clot through various ultrasonic mechanisms such as cavitation bubbles and microjets which expose the clot to strong localized shear and tensile stresses. These prior art devices are usually operated in conjunction with a thrombolytic drug and/or a radiographic contrast agent to facilitate visualization.

[0012] The ultrasonic catheter devices all have a common configuration in which the source of the vibrations (the transducer) is external to the catheter. The vibrational energy is coupled into the proximal end of the catheter and transmitted down the length of the catheter through a wire that can transmit the sound waves. There are associated disadvantages with this configuration: loss of energy through bends and curves with

concomitant heating of the tissues in proximity; the devices are not small enough to be used for treatment of stroke and are difficult to scale to smaller sizes; it is difficult to assess or control dosimetry because of the unknown and varying coupling efficiency between the ultrasound generator and the distal end of the catheter.

[0013] U.S. Patent No. 5,380,273, attempts to improve on the prior art devices by incorporating advanced materials into the transmission member. Placement of the ultrasonic transducer itself at the distal end of the catheter has been impractical for a number of reasons including size and power requirements. [0014] A related method for removing occlusions is laser angioplasty in which laser light is directed down an optical fiber to impinge directly on the occluding material. Laser angioplasty devices have been found to cause damage or destruction of the surrounding tissues. In some cases

uncontrolled heating has led to vessel perforation. The use of high energy laser pulses at a low or moderate repetition rate, e.g. around 1 Hz to 100 Hz, results in non-discriminatory stress waves that significantly damage healthy tissue and/or result in insufficient target-tissue removal when the independent laser parameters are adjusted such that healthy tissue is not affected. Use of high energy laser light to avoid thermal heating has been found to cause damage through other mechanisms associated with large cavitation bubbles and shock waves that puncture or otherwise adversely affect the tissue.

[0015] United States Patent No. 6022309 A, discloses a catheter-based device for generating an ultrasound excitation in biological tissue. Pulsed laser light is guided through an optical fiber to provide the energy for producing the acoustic vibrations. The optical energy is deposited in a water-based absorbing fluid, e.g. saline, thrombolytic agent, blood or thrombus, and generates an acoustic impulse in the fluid through thermoelastic and/or thermodynamic mechanisms. By pulsing the laser at a repetition rate (which may vary from 10 Hz to 100 kHz) an ultrasonic radiation field can be established locally in the medium. The limitation is a localized area of acoustic vibrations: indeed the laser energy is deposited in a volume of fluid comparable to the fiber dimension. [0016] Accordingly, it would be desirable to provide a device for removing occlusion, such as a catheter or guide wire that permits generating ultrasound excitation directly in contact to occlusion without loss of energy along a small size catheter and in a large area around the distal part of the device. Treatment of Ablation [0017] To provide effective diagnosis or therapy, it is frequently necessary to first map the zone to be treated with accuracy. Such mapping can be performed, for example, when it is desired to selectively ablate current pathways within a heart to treat atrial fibrillation. Once the topography of the vessel or organ is mapped, either the same or a different catheter can be employed to effect treatment.

[0018] Maintaining optimal catheter tip-tissue contact is vital for delivering robust radiofrequency (RF) lesions but is a constant challenge during catheter ablation. Improved contact reduces dissipation of energy into the circulating blood pool resulting in better energy coupling to tissue. The importance of contact force in creating RF lesions has been well documented and is particularly pertinent in light of the fact that

contemporary irrigated tip catheters (irrigation with saline) preclude accurate tissue temperature monitoring during ablation. [0019] Recent advances in catheter technology have included the use of fiber optic force sensors to detect the reactive force at the distal extremity of an end effector when placed in contact with the interior wall of a vessel or organ. It is well known about an apparatus including a plurality of optical fibers that direct light onto a mirrored surface disposed adjacent to a distal tip of the device. The intensity of the light reflected from the mirrored surface is measured and may be correlated to the force required to impose a predetermined amount of flexure to the distal tip.

WO2007/01 5139 discloses a device and method for resolving a force vector (magnitude and direction) applied to the distal end of a catheter. It discloses the use of fiber optic strain elements in a catheter that maintains essentially the same profile as with catheters that do not sense touching forces and is substantially immune to electromagnetic interference. United States Patent No. 8,075,498, discloses a force sensing catheter system that utilizes the deformation of fiber Bragg grating strain sensors to infer the force incident upon the tip of the catheter. United States Patent No.

8,048,063 discloses a tri-axial force sensor having a deformable structure that isolates the deflections caused by forces imposed on the distal end of the catheter and wherein fiber optics both irradiate and receive reflected light from the deformable structure, with intensities of the received reflected light varying according to the imposed force. US2009/0287092 discloses a fiber optic touch sensing catheter that incorporates multiple temperature sensors for active compensation of the effects caused by temperature changes, including a calibration technique for reducing thermally induced errors. United States Patent No. 8,1 57,789 discloses a fiber optic touch sensing catheter that utilizes an interferometric principle to detect structural deformations of a strain sensing assembly to infer forces. [0020] US201 161475384 discloses an ablation catheter system configured with a compact force sensor at a distal end for detection of contact forces exerted on an end effector. The force sensor includes fiber optics

operatively coupled with reflecting members on a structural member. In one embodiment, the optical fibers and reflecting members cooperate with the deformable structure to provide a variable gap interferometer for sensing deformation of the structural member due to contact force.

[0021] Accordingly, it would be desirable to provide diagnostic and treatment apparatus, such as a catheter or guide wire, that permits sensing of loads applied to a distal extremity of the apparatus, but which do not substantially increase the insertion profile of the apparatus. It is further desirable to provide diagnostic and treatment apparatus, such as a catheter and guide wire, that permits not only computation of forces but also a complete mapping of the touch interaction between the device and the tissue. A fiber optic touch mapping catheter that combines compactness, high sensitivity and relative insensitivity to temperature change, all while being relatively easy to fabricate, would be a welcome advance in the field of minimally invasive procedure.

Stone Management in Urology

[0022] Lithotripsy is a medical procedure involving the physical destruction of hardened masses like kidney stones (also known as a renal calculus)., or gallstones (also called cholelithiasis). Three technologies and associated devices are widely used: external lithotripsy with pneumatic shock wave generator, Holmium Laser and ultrasound generator. The last two technologies are minimally invasive procedures. Although well established for the practitioners, the systems require high energy input in order to use enough energy at the distal part of the probe (such as a wave guide for ultrasound and an optical fiber for Holmium Laser) to fragment the calculi or stones. It would be a welcome to generate directly at the distal part of the probe limited energy to efficiently perform lithotripsy procedures. [0023] It is also desirable that a catheter be equipped with a surface acoustic wave sensor for detecting, measuring and/or determining a three dimensional contact force vector acting upon the catheter tip and wherein it is possible to determine the tip electrode contact area in relation to the heart wall and thus calculate the tip electrode contact pressure. [0024] In all those fields, catheter type devices are used with the mentioned drawbacks. Catheter type devices define in this application any medical or dental device. A catheter type device is preferably a medical or dental device with an elongated member configured to be inserted in a body, e.g. a tooth, a vein, a body channel, any body cavity. A catheter type device comprises preferably one of a therapeutic catheter, a diagnostic catheter, a guidewire, an elongated and flexible probe, a needle or a dental tip or any combination of them.

[0025] It is also desirable to manufacture by surface technologies catheter type devices with added value for lower cost. Brief summary of the invention

[0026] According to one embodiment, these aims are achieved by a catheter type device according to the independent claims.

[0027] According to one embodiment of the invention, the energy needed for creating the acoustic waves needed for ultrasonic treatment is transferred to the desired place in the catheter type device or medical device by light or by radio waves. Therefore, the transmission losses are minimized and the acoustic waves are generated only at the desired location. [0028] According to one aspect of the invention, the energy source and the place of ultrasonic excitation is connected by an optical conductor. The energy source is preferably a light source and the ultrasonic excitation means is realized by a piezoelectric material transforming at least one wavelength of the light source in mechanical movement, in particular in ultrasonic vibrations.

[0029] The use of optical energy to induce an ultrasonic excitation in the tissue offers a number of advantages. Optical conductors like fibres can be fabricated to small dimensions, yet are highly transparent and capable of delivering substantial optical power densities from the source to the delivery site with little or no attenuation. This reduces energy loss and heat development between the desired place of ultrasonic excitation and the energy source. Optical fibers are also flexible enough to navigate all vessels of interest. The method may also incorporate an optical feedback

mechanism for monitoring and controlling the magnitude of the acoustic vibrations induced in the tissue.

[0030] According to one embodiment, these airms are achieved by a catheter type device for minimally invasive procedure comprising at least one optical fiber wherein at least one area of the optical fiber is covered by at least one piezoelectric film such that a light propagating into the optical fiber is in interaction with the piezoelectric film and the piezoelectric film is then actuated and generates mechanical waves.

[0031] According to one embodiment, these aims are achieved by a method with the following steps: inserting at least one fiber optic with at least one coated piezoelectric material into said vasculature; actuating said piezoelectric material by light energy, generating ultrasonic radiation field by the emission from the piezoelectric material of mechanical waves; controlling said light energy such that the maximum size of a cavitation bubble is approximately the same as the fiber diameter; and pulsing said light energy at a repetition rate such that multiple cycles of this process generates an acoustic radiation field in the surrounding fluid [0032] According to one embodiment, these aims are achieved by a catheter type device adapted for mapping and/or ablation, comprising: a tube means adapted for passage through a vessel in a patient's body; at least one electrode distal the tubing, the electrode configured for contact with body tissue for mapping or ablation; at least one part of the tubing is coated with a piezoelectric material; and mechanical wave generation means propagating mechanical waves into or onto the piezoelectric part defining a strain sensing area.

[0033] According to one embodiment, these aims are achieved by a method, comprising: providing a pressure and/or flowrate sensing catheter type device that includes: an elongate tubular member having a proximal portion and an opposing distal portion; a flexible element coupled to the distal portion of the elongate tubular member, the flexible element having an increased flexibility compared to the elongate tubular member; at least one surface acoustic wave sensor comprising at least one piezoelectric material coated onto the flexible element, at least one surface acoustic wave emission means linked to the coated piezoelectric material, and at least one propagating surface acoustic wave area defining the sensing area; a reader sending an interrogating signal to the sensor, generating surface acoustic wave from said emission means, and receiving response from the sensor; and inserting at least a distal portion of the pressure and/or flowrate sensing catheter type device into a vessel having a stenosis;

obtaining a first pressure measurement and/or a first flowrate

measurement within the vessel with the propagating surface acoustic wave area positioned proximal of the stenosis; and obtaining a second pressure measurement and/or a second flowrate measurement within the vessel with the propagating surface acoustic wave area positioned distal of the stenosis. [0034] According to one embodiment, these aims are achieved by a catheter type device for endodontic procedure having at least one elongated structure with a proximal part and a distal part, wherein the distal part of the structure comprises at least one piezoelectric material coated onto the distal part such that the piezoelectric material can be actuated by at least one energy source.

[0035] According to one embodiment, these aims are achieved by a method for root canal therapy or endodontics using a catheter type device integrating an elongated structure comprising at its distal part at least one coated piezoelectric material actuated by at least one energy source;

inserting the device in a root canal and performing cleaning and/or treatment of said root canal by actuating the piezoelectric material by the energy source.

[0036] According to one embodiment, these aims are achieved by a catheter type device comprising an elongated structure have a distal part and a proximal part, wherein at least one part is coated by at least one piezoelectric material; at least one interdigital transducer is in contact with said piezoelectric material; and at least one reader communicating with the transducer such as the reader send at least one signal to the transducer which generates surface acoustic wave on the piezoelectric material.

[0037] According to one embodiment, these aims are achieved by a method using a tip or file for dental procedure such as root canal therapy integrating a coated piezoelectric material structure; comprising the steps of: Inserting into root canal the tip or file; Switching on the radiation which propagates into the structure such that the radiation wavelength is specific to the nature of the piezoelectric material; Actuating the piezoelectric material; Performing cleaning of the root canal or relevant step procedure for root canal therapy.

[0038] The dependent claims and the following features refer to further advantageous embodiments. [0039] In one embodiment said optical fiber is for use in optical coherent tomography, said optical coherent tomography integrating a plurality of light sources.

[0040] In one embodiment a surface of the piezoelectric film is chemically functionalized. For example, the functionalized piezoelectric film further integrates at least one active agent for controlled release.

[0041] In one embodiment, said fiber optic is located within a catheter, said device further comprising injecting through said catheter into liquid ambient medium a thrombolytic drug to emulsify occlusion. [0042] In one embodiment, the magnitude of the acoustic vibrations induced in the tissue is monitored and controlled through a feedback mechanism.

[0043] In one embodiment, said mechanical waves generates acoustic radiation field in a liquid ambient medium for the removal of an intravascular occlusion in a blood vessel or stone as part of urology procedures.

[0044] In one embodiment, a laser light is used as a signal source for producing acoustic images of structures in body tissues.

[0045] In one embodiment, said light source comprises a tunable wavelength.

[0046] In one embodiment, said catheter type device further comprises means for resolving a force vector from said at least one strain sensing area.

[0047] In one embodiment, said catheter type device further comprises temperature compensation means. [0048] In one embodiment, said mechanical wave generation/emission means are interdigited transducers.

[0049] In one embodiment, the surface acoustic wave sensor has a (surface acoustic wave) resonator type design or a delay line type design a combination of the both design.

[0050] In one embodiment, the surface acoustic wave sensor is operating wirelessly.

[0051] In one embodiment, the sensor or the catheter type device further comprises at least one (thin) membrane. This membrane is preferably linked to the piezoelectric material.

[0052] In one embodiment, wherein at least one guiding layer is linked to the piezoelectric material and/or to the sensor.

[0053] In one embodiment, the sensor integrates at least one shear horizontal surface acoustic wave emission means [0054] In one embodiment, the catheter type device is suitable for endodontic procedure, wherein the structure is an optical fiber and said energy source is a radiation. Preferably this energy source is an electrical energy.

[0055] In one embodiment, the catheter type device comprises at least one irrigation channel.

[0056] In one embodiment, the catheter type device is connected to or comprises a handpiece.

[0057] In one embodiment, the handpiece integrates the energy source

[0058] In one embodiment, the catheter type device is connected to an optical coherence tomography platform. [0059] In one embodiment, the structure is integrated in a tubular element.

[0060] In one embodiment, the piezoelectric material has a thickness gradient. [0061] In one embodiment, the piezoelectric material further comprising at least one dopant specie.

[0062] In one embodiment, the surface acoustic wave is in contact with tissue to perform measurements.

[0063] In one embodiment, the piezoelectric material is removable from the device.

[0064] In one embodiment, the light has an ultraviolet wavelength.

[0065] In one embodiment, the catheter type device comprises a force sensing area at a distal end for detection and mapping of contact forces.

[0066] In a preferred embodiment of the catheter type device wherein advantageously the surface acoustic wave are in contact with tissue to perform measurements such as chemical specie identification or

characterization, pressure, temperature, flowrate, viscosity...

[0067] The present invention provides means for in situ cleaning in endodontic treatment, or for dissolution of a vascular occlusion by generating directly ultrasonic excitation in the fluids inside the root canal, or in close proximity or, according to the case, directly inside a vascular occlusion to further its fragmentation.

Brief Description of the Drawings

[0068] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention. In the drawings:

Figure 1 shows a view of an optical fiber with a deposited piezoelectric material actuating when absorbing light guided by the fiber;

Figure 2 shows a representation of an Endodontic tip or file integrating a coated piezoelectric material structure;

Fig 3 shows a schematic representation Endodontic tip with irrigation channel;

Fig 4 shows a schematic representation endodontic tip wherein a coated piezoelectric material structure is integrating in a tubular element;

Figure 5 shows a schematic representation of an optical coherence tomography integrating an optical fiber where a part of it is coated by a piezoelectric material actuating by lighting through the fiber;

Figure 6 shows a part of a catheter type device with a design integrating a surface acoustic wave technology;

Figure 7 shows a part of a catheter type device integrating coated interdigited electrode onto a piezoelectric film deposited onto the device. A delay line design comprises a plurality of reflectors;

Figure 8 shows a part of a catheter type device integrating a plurality of Surface acoustic wave generation means; Figure 9 shows a view of a SAW technology embedded in a catheter type device comprising a guiding layer;

Figure 10 shows a top view schematic representation of a Catheter type device with haptic functionality in the distal part; and

Figure 1 1 shows a schematic representation of a Catheter type device with haptic functionality when a force is applied on the distal part of the device;

Figure 12 shows a SAW resonator design integrated onto a catheter type device;

Figure 13 shows a SAW Delay line Design integrated onto a catheter type device.

Detailed Description of possible embodiments of the Invention

[0069] The Figure 1 shows the basic principal of one embodiment of the catheter type device. The catheter type device comprises an optical conductor 1 and a material 2.

[0070] The material 2 is configured to transform optical waves received over the optical conductor 1 into a mechanical movement of the material 2. The material 2 absorbs optical waves and transforms the absorbed energy of the optical waves in mechanical movement of the material 2. An example for such a material 2 is a material configured to perform

photostriction. The material 2 is arranged at the desired position for the mechanical movement. In one embodiment, the movement of the material 2 is a vibration, i.e. a periodic movement of the material 2. Preferably, it is an ultrasound vibration. The periodic movement leads normally to a surface acoustic wave (SAW) on the conductor 1 . In one embodiment, the material 2 has at least one activation wavelength for which the material 2 absorbs optical waves and transforms those optical waves of the activation wavelength into the mechanical movement. In one embodiment, the activation wavelength is in the ultraviolet range, but other optical wavelengths are possible.

[0071] In one embodiment, the material 2 is arranged at the distal end of the conductor 1. In one embodiment, the material 2 is coated at the circumference of the optical conductor 1 . In one embodiment, an

intermediate substrate is arranged between the material 2 and the optical conductor 1 to increase bonding between the optical conductor 1 and the material 2. This could be for example a primer. The substrate should be configured to transfer the optical energy of the optical waves at the activation energy. In one embodiment, the material 2 is a piezoelectric material. The piezoelectric material 2 may be a Zinc oxide (ZnO), or

Aluminium nitride (AIN), or a Lithium Niobium Oxide (LiNbO), or a combination of them. However, other piezoelectric materials 2 might be possible. If the piezoelectric material is ZnO, the wavelength of the radiation is about 360nm because the ZnO absorbance is max. Other parameters such as piezoelectric material porosity or dopant concentration in the material 2 could be taken into account in order to improve the radiation absorbance and/or the material adherence onto the fiber. In a preferred embodiment of the invention, a catheter type device integrates the piezoelectric material further comprising at least one dopant species. In an alternative embodiment (not shown here), the material 2 could be also arranged at the distal end of the optical conductor in continuation of the optical conductor. In this case, the material 2 is arranged at the distal end of the optical conductor 1 in the conducting axis of the conductor.

Preferably, the conductor 1 forms at the distal end a contact surface, preferably in the form of the bottom of a cylinder, which contacts to the material 2. Preferably, the outer dimensions and/or form of a cross-section through the material 2 is (substantially) the same as those of a cross-section of the conductor 1 . Preferably, both cross-sections are aligned. This embodiment has the advantage that the material 2 is arranged where the light exits the conductor 1 anyway and the material 2 can absorb a maximal energy from the conducted light. [0072] The thickness of the material 2 influences the frequency of the created mechanical vibration. Therefore, the thickness can be used in order to define the frequency or the frequency spectrum of the created

mechanical vibrations (or of the respective surface waves). In one

embodiment, the thickness of the material 2 is constant. In one

embodiment, the material 2 has a plurality of thicknesses in order to create a plurality of frequencies. This could be realized e.g. by a thickness gradient in order to create a frequency spectrum. In one embodiment, there is a plurality of materials 2 with different thicknesses for creating multiple frequency vibrations. Those different materials 2 could be made of the same substance. In an alternative embodiment, the different materials 2 could be made of different substances such that the creation of the different frequencies could be activated by different activation

wavelengths of the optical waves. In this embodiment, the different materials 2 could be activated individually and independently

notwithstanding the use of only one optical conductor. In another embodiment, each of the different materials 2 are connected by its own optical conductor 1 .

[0073] The optical conductor 1 is configured to transfer the optical waves to the material 2. The optical conductor 1 is configured to conduct at least one activation wavelength of the material 2. In one embodiment, the optical conductor 1 is an optical fiber. However, any other optical conductors 1 might be used. In one embodiment, the optical conductor 1 is flexible, even though the invention would also work with rigid optical conductors 1 . In one embodiment, the optical conductor 1 in the boundary surface with the material 2 allows the penetration of the optical waves, in particular of the activation wavelength.

[0074] The catheter type device may further show an optional optical source (not shown in Fig. 1 ). The optical source is configured to create optical waves with at least one activation wavelength of the material 2. Obviously, if the material 2 has a plurality or a range of activation wavelengths, the light source could use only one, a subset or all of those activation wavelengths to activate the material 2. It is also possible that the optical source 2 is configured to create optical waves comprising

additionally to at least one activation wavelength other wavelengths not activating the material. This might be simply due to the nature of the optical source or for secondary uses of the optical wavelengths, e.g.

monitoring, detection, etc.. In one embodiment, the optical source is arranged at the proximal end of the conductor 1 . However, the catheter type device may not incorporate an optical source, but may show only an interface at a proximal end of the optical conductor 1 configured to be connected to a suitable optical source. [0075] The catheter type device according to this embodiment has the advantage that optical waves are used to transfer energy over the optical conductor 1 to the desired position for mechanical vibrations. The material

2 which transforms the optical waves into a mechanical movement is arranged at the desired position. In response to the reception of the optical waves at the material 2, mechanical vibrations are generated only at the desired position almost without any loss of energy, because optical energy can be transferred with a very low energy loss.

[0076] A catheter type device according to Fig. 1 could be used in many medical and dental fields. In fluid filled vessels the material 2 could generate locally concentrated vibrations in the fluid. The local vibrations could produce collapsing cavitation bubble in the fluid which is an advantage for specific minimally invasive procedures such as intracorporeal lithotripsy. The conductor 1 could inserted in the desired vessel such that the vibrations are created only in the vessel and not along the conductor 1 . [0077] Figure 2 shows an embodiment of the catheter type device as described in Fig. 1 . Here the catheter type device is an endodontic tip or file

3 having a handpiece 3' and an elongated member. The elongated member comprises the optical conductor 1 and the material 2 coated on the surface of the elongated member. The elongated member could be consituted directly by the optical conductor 1 such as an optical fibre or could provide a tube structure including therein the optical conductor 1 . The elongated member and thus the conductor 1 could be integrally formed with the handpiece 3' or could be attachable with the proximal end of the

elongated member or of the conductor 1 to the handpiece 3'. In one embodiment, the handpiece 3' may comprise the optical source, e.g. a LED. Alternatively, the handpiece 3' may be provided with the optical waves by a further optical conductor.

[0078] Figure 3 shows a variation of the endodontic tip or file 3 of Fig. 2 further comprising an irrigation channel 4 . The irrigation channel 4 is connected on one side with a reservoir for the irrigation fluid or with a connector for connecting the irrigation channel 4 to such a reservoir. On the opposed side, the irrigation channel 4 opens on the handpiece 3' in vicinity of the elongated member in order to irrigate an irrigation fluid in the root canal. Such tip or file 3 can be used also for prophylaxis

procedures.

[0079] Figure 4 shows a variation of the endodontic tip or file 3 of Fig. 2, wherein the elongated member or the conductor 1 is integrated in a tubular element 5. The tubular element 5 may be formed such as a drill. The advantage of this embodiment is that the practitioner can not only use the piezo functionality, thanks to said vibrations he can perform efficient cleaning into the root canal, but he can also actuate the tubular element 5 to prepare the canal for the next step of the procedure which is the filling by cement type material such as gutta percha.

[0080] A method using a tip or file 3 for dental procedure, e.g. a root canal therapy, integrating an elongated member coated with a material 2; comprising the steps of: Inserting into root canal the elongated member or the conductor 1 (at least a part of the material 2 should be inserted in the root canal); Switching on a light radiation with at least one activation wavelength which propagates into the conductor 1 ; as a consequence, the piezoelectric material 2 starts actuating/vibrating; Performing cleaning of the root canal or relevant step procedure for root canal therapy. [0081] In an embodiment of a catheter type device according to Fig. 1 comprising additionally an optical detector configured to detect optical waves captured at the distal end of the optical conductor 1 and transmitted via the conductor 1 to the optical detector. An example for such an optical detector is an optical coherence tomography system as shown in Fig. 5. The advantageous configuration allows on one hand the use of optical fiber for tomography and on the other hand, without changing the conductor 1 during the minimally invasive procedure, to perform vibration actuation by lighting the piezoelectric material. The optical detection mode and the mechanical wave generation mode could be controlled independently by using a optical waves for the detection mode with another wavelength or other wavelengths than the activation frequencies of the material 2.

Therefore, the detection mode could be performed without the activation of the material 2. It is also possible to perform detection and activation at the same time by inserting detection optical waves and activation optical waves at the same time in the conductor 1 . However, preferably the detection is performed in another time window than the activation in order to deteriorate the measurements in the detection mode. In another embodiment, the same optical waves are used for detection and activation. However, this has the disadvantage that the detection can only be performed at the same time with the activation. Accordingly, the same or different optical sources can be used for the detection and the activation mode. In the case the same optical source is used, the optical source may be controllable to emit optical waves with different wavelengths. Preferably, the optical source is a laser.

[0082] In the following a potential application of the catheter type device is described. The device produces an ultrasonic radiation field in a fluid by: (i) depositing e.g. optical energy transferred by the material 2 in acoustic energy in a volume of fluid. The volume of the fluid is comparable to the fiber dimension. The time scale of duration of the optical wave pulse is less than the acoustic transit time across this dimension (as controlled by choice of laser wavelength and absorbing fluid as the case may be), (ii) The laser energy is controlled such that the maximum size of the cavitation bubble is approximately the same as that of the fiber diameter, (iii) The laser is pulsed at a repetition rate such that multiple cycles of this process generates an acoustic radiation field in the surrounding fluid; resonant operation may be achieved by synchronizing the laser pulse repetition rate with the cavity lifetime.

[0083] The bubble expansion and collapse couples acoustic energy into the fluid. Subsequent laser pulses are delivered to repeat or continue this cycle and generate an ultrasonic radiation field at a frequency or frequencies determined by the laser pulse frequency. Similar to the first mode, a resonant operation may be achieved by matching the laser pulse period to the lifetime of the cavitation bubble.

[0084] In a preferred embodiment of the invention, a device where the fiber optic is located within a catheter, said device further comprising injecting through said catheter into liquid ambient medium a thrombolytic drug to emulsify occlusion.

[0085] In a preferred embodiment of the invention, a catheter type device wherein said fiber optic is located within a catheter, said device further comprising injecting through said catheter into liquid ambient medium a radiographic contrast agent to facilitate visualization.

[0086] In another embodiment, the energy transmission to the material 2 is replaced by a wireless radio signal. Fig. 6 to 1 1 shows such

embodiments. [0087] Fig. 6 shows a medical device, preferably a catheter type medical device, comprising a tubular element 50, a piezoelectric material 52, an interdigital transducer 53 (also called interdigited electrode) and a signal input.

[0088] The tubular element 50 is preferably adapted to be inserted or implanted in body cavities, like vessels, veins and other body cavities. The cross-section of the tubular element 50 is preferably circular, but can have any other form like ellipsoid, rectangular, etc. [0089] The piezoelectric material 52 is preferably arranged on the curved surface area of the tubular element 50. In one embodiment, the piezoelectric material 52 is arranged on the complete circumference of the tubular element 51 (at least over a certain distance along the longitudinal axis of the tubular element 51). However, it is also possible that the piezoelectric material 52 does not cover the complete circumference. The tubular element might be an optical conductor according to Fig. 1 to 5 such that the piezoelectric material 2 / 52 for the embodiment of Fig. 1 to 5 and the here described embodiment can be shared. The piezoelectric material 2 may be a Zinc oxide (ZnO), or Aluminium nitride (AIN), or a Lithium

Niobium Oxide (LiNbO), or a combination of them. However, other piezoelectric materials 2 might be possible.

[0090] The interdigital transducer 53 is arranged on the piezoelectric material 52. The interdigital transducer 53 is configured to induce a surface acoustic wave based on a certain input signal. The interdigital transducer 53 comprises preferably two interlocking electrodes, e.g. comb-shaped arrays of electrodes. The interdigital transducer 53 is preferably arranged such that the principal direction of distribution of the surface acoustic wave is the direction of the longitudinal axis of the tubular element 51 . This could be achieved by arranging the electrode fingers of the two comb- shaped arrays along the circumferential of the tubular element 51 and rectangular to the longitudinal axis of the tubular element 51 . The interdigital transducer 53 is configured to create a surface acoustic wave with at least one wavelength. The wavelength could be influenced by the distance between the fingers of the two interdigital electrodes and by the dimensions, especially in direction of the longitudinal axis of the tubular element 51 . In one embodiment, the surface acoustic wavelength comprises a plurality of wavelengths.

[0091] The signal input is here realized as an antenna 54 which is connected to at least one electrode of the interdigital transducer 53, here to both electrodes. This allows to receive a radio signal at the antenna 54 which induces a surface acoustic wave by the interdigital transducer 53 on the piezoelectric material 52. The antenna 54 could be realized as a coil. However, other signal inputs might be also possible like an electric conductor.

[0092] In the shown embodiment in Fig. 6, the medical device comprises a second interdigital transducer 53' and a second antenna 54'. The second interdigital transducer 53' is configured to receive the surface acoustic wave transmitted by the first interdigital transducer 53, to transfer it to an electric signal and to send this electric signal back over the second antenna 54' as a feedback signal. This feedback signal could have a number of functions. In one embodiment, it could be used to control the induced surface acoustic wave on the basis of the feedback signal by varying the input signal. In one embodiment, it could be used to measure a stain or deformation of the tubular element. In one embodiment, it could be used to sense qualitative or quantitative information relevant for said medical procedure. Those functions could be performed by a controller being part of or being external to the medical device. This allows to measure a force and/or position of a touching point, where the tubular element might touch something, e.g. a cavity, a vessel or a vein of the body. Also the second antenna 54' could be replaced by other output means like e.g. an electric conductor. The second interdigital transducer 53' is arranged like the first interdigital transducer 53 such that the principal direction for receiving surface acoustic waves is parallel to the longitudinal axis of the tubular element 51. Preferably, the interdigital transducer 53' is arranged so on the circumference of the tubular element 51 that the projection of the first interdigital transducer 53 in the direction of the longitudinal axis of the tubular element 51 corresponds to the second interdigital transducer 53'. However, other arrangements of the interdigital transducer 53' compared to the first interdigital transducer 53 is possible.

[0093] In one embodiment, the catheter type device may comprises a coated and chemically functionalized piezoelectric material 52. The surface acoustic waves may act as trigger for drug release function interacting with liposomes fixed to the piezoelectric function wherein active agents are embedded into the liposomes. [0094] Fig. 7 shows a further embodiment of the medical device described in Fig. 6. The medical device replaces here the second transducer 53' and the second antenna 54' by at least one reflector 56, 57, 58. The surface acoustic wave induced by the interdigital transducer 53 is reflected by each of the at least one reflector 56, 57 and 58. The reflected signal(s) received at the interdigital transducer 53 is sent back as a feedback signal. The feedback signal can have the same functions as in the first embodiment of Fig. 6. Another function would be the identification of the tubular element by the at least one delay times or their relative time differences. In this embodiment, only one of the two electrodes of the interdigital transducer 53 is connected to the antenna, while the other is connected to earth.

[0095] Referring to figure 8, a medical device according to Fig. 7 comprising a second antenna 64, a second interdigital transducer 63 and a second at least one reflector 66, 67 and 68. The first interdigital transducer 53 - reflector 56, 57, 58 - arrangement might have another function than the second interdigital transducer 63 - reflector 66, 67, 68 - arrangement. Maybe identification the first and sensing the second. Each transducer could have an independent design of the other, e.g. one with a reflector 56, the other with a second interdigital transducer 53'. Such a reflector could be superfluous, if the tubular element 51 provides natural reflections.

[0096] In general a plurality of interdigital transducers might be arranged on the tubular element 51 . The interdigital transducers might have each another function. They might be arranged on one or a plurality of coated piezoelectric materials or on the same coated piezoelectric materials.

[0097] Figure 9 shows longitudinal cross-section of the coating on the tubular element 51 of the embodiment of Fig. 6. The piezoelectric material 52 is coated on a substrate 71 . The material 72 between the piezoelectric material 52 of the first interdigital transducer 53 and the second

interdigital transducer 53' is (at least in the line of sight) the same

piezoelectric material 52 such that there are no reflecting bounderies for the surface acoustic wave between the two interdigital transducers 53 and 53'. However, the material 72 could be also different to the piezoelectric material 52. The piezoelectric material 52 and/or the material 72 can be covered by a cover layer 73. In one embodiment, this layer is isolating in order to isolate the electrodes of the transducers. In one embodiment, the layer 73 has some special chemical or biological effects. In one

embodiment, the layer is configured to slow down the velocity of the surface acoustic wave at the border surface between the piezoelectric material 52 and the layer 73. In one embodiment, the layer 73 guides the surface acoustic wave to the second transducer 53' or to a reflector 56, 57, 58. The effect of the guiding layer 73 is to trap the acoustic energy near a sensing surface, reducing propagation velocity and increasing the sensitivity to surface perturbations. The sensing surface could be for example the surface where a touch could be detected or quantified. In another embodiment, the sensing surface could be a chemically or biologically functionalized region, where the surface acoustic wave passes. Depending on the chemically or biologically bonded material to this functionalized region, the surface acoustic wave in this region changes. Therefore, biological or chemical measurements could be performed on the basis of the feedback signal. In all described embodiments in this patent

application, the piezoelectric material could be covered by a layer 73. In this case, the surface acoustic waves become bulk acoustic waves.

[0098] Figure 10 shows a figurative top view of the tip of the tubular element 51. Preferably, the tip of the tubular element 51 is round to be configured for continuous acoustic surface wave propagation. The tip or the cylindrical side wall of the tubular element or both could comprise the first interdigital transducer 53 as described in the figures before. In this embodiment, comprise a plurality of interdigital transducers at the tip or at the cylindrical side wall of the tubular element 51 close to the tip. At least one of the plurality of transducers create surface acoustic waves and at least one of the plurality of transducers measures the surface acoustic waves and sends it back via an antenna. Preferably, a plurality of

interdigital transducers measure the surface acoustic waves in order to locate the place and/or force (amplitude and/or direction) of a touch of the tubular element in more detail. However, also with one interdigital transducer already a rough determination of the place of the touch and whether there is a touch is possible. The interdigital transducers could be used as sender and as receivers or there could be interdigital transducers used only for sending and ones only for receiving. Like this, a haptic function of the medical device can be realized. With a plurality of interdigital transducers on the tubular element 51 , a real time mapping of acoustic wave propagation could be realized leading to the mapping of forces interacting with the piezo parts. [0099] Referring to Figure 1 1 (side view), a haptic function catheter type device 1 10 for use in a medical procedure device is depicted wherein the distal part is covered/coated by at least one layer of a piezoelectric material 1 13 and at least one interdigited electrode 1 12 which generates surface acoustic waves (SAW) 1 1 1 on the piezoelectric material when energy is provided (wirelessly or not) to the electrode by an input signal. When a force or a contact is applied locally to the part the SAW propagation is locally modified and the output signal towards a controller is analyzed to quantify the force or the contact.

[00100] In a preferred embodiment of the invention, the haptic function catheter type device further comprising means for Radiofrequency (RF) ablation procedure.

[00101] A method using an haptic function catheter type device for medical procedure, wherein surface acoustic waves propagates on at least one piezoelectric part of the device generated by at least one interdigited electrodes actuated by an input signal; un force or a contact is applied on the piezoelectric part modifying the SAW propagation; and characterizing the output signal from the electrode to a controller; the output signal leads to quantitative information about the force such as amplitude and orientation(vector). A plurality of piezoelectric parts may give quantitative information on a mapping in real time of force or contact applied to the parts. [00102] It is understood that it is still within the scope of the invention depending upon the specific treatment to be applied to the vessel or organ, the catheter type device may comprise any of a number of haptic function, such as but not limited to RF ablation electrodes, rotary or scissor action cutting heads, laser ablation, injection or sewing needles, fluid conveyance systems, forceps, manipulators, mapping electrodes, endoscopic vision systems and therapeutic delivery systems such as genetic

impregnation devices

[00103] Figure 12 shows a representation of a surface acoustic wave delay line design integrated onto a catheter type device. A resonator is composed of an interdigital transducer in the center of the structure and reflecting gratings or electrodes on both sides of the interdigital transducer. The interdigital transducer is a bi-directional structure, it means the energy propagates on both sides at the same intensity. The reflecting gratings or electrodes reflect the energy produces by the interdigital transducer.

[00104] A resonant cavity is obtained and characterized by its resonant frequency. Advantages: high quality factor, low insertion losses. Such an arrangement could also be used in the embodiments shown before.

[00105] Figure 13 shows a representation of a surface acoustic wave delay line design integrated onto a catheter type device. A delay line is composed of an interdigital transducer at one side of the device and reflecting gratings or electrodes (reflector) at the other side. The interdigital transducer generates an impulse wave which propagates to the electrodes. The impulse wave is reflected by the electrodes or reflecting gratings to the interdigital transducer.

[00106] We therefore measure the propagating time of an impulse.

Advantages: no sensitivity of phase shifts to manufacturing tolerances. In a preferred embodiment of the invention, the electrodes are deposited on a piezoelectric material which is coated on the catheter type device. At least one intermediate layer of a specific material between the piezoelectric material or film and the catheter type device can be deposited to enhance the adherence of the piezoelectric layer on the catheter type device.

[00107] The catheter type device/medical device can be used for to generate an acoustic radiation field in a liquid ambient medium for the removal of an intravascular occlusion in a blood vessel or stone as part of urology procedures. The catheter type device could be used for root canal therapy or endodontics using. Such a catheter type device is often also called endodontic tip or file 3. Therefor, the conductor 1 or a tube containing the conductor 1 is inserted in a root canal and cleaning and/or treatment of said root canal is performed by actuating the piezoelectric material by the optical waves.

[00108] The embodiments above were described in the context of a catheter type device, but could be used for any medical or dental device.

[00109] Applications envisioned for this invention include any method or procedure whereby localized ultrasonic excitations from a piezoelectric material deposited onto an optical fiber and actuating by a radiation are to be produced in the body's tissues through application of a probe. The invention may be used in (i) endovascular treatment of vascular occlusions that lead to ischemic stroke, (ii) endovascular treatment of cerebral vasospasm (This technology can relax vaso-constriction leading to

restoration of normal perfusion and therefore prevent further transient ischemic attacks or other abnormal perfusion situations), (iii) endovascular treatment of cardiovascular occlusions (This technology can lyse thrombus or remove atherosclerotic plaque from arteries), (iv) endovascular treatment of stenoses of the carotid arteries, (v) endovascular treatment of stenoses of peripheral arteries, (vi) general restoration of patency in any of the body's luminal passageways wherein access can be facilitated via percutaneous insertion, (vii) any ultrasonic imaging application where a localized (point) source of ultrasonic excitation is needed within an organ or tissue location accessible through insertion of a catheter, (viii) lithotriptic applications including therapeutic removal of gallstones, kidney stones or other calcified objects in the body and (ix) as a source of ultrasound in ultrasound modulated optical tomography.

[00110] In a preferred embodiment of the invention, the piezoelectric material 2, 52 or film 73 , deposited onto the catheter type device is chemically functionalized for improving the interaction of the device with its environment such as hemocompatibility of the device.

[00111] In a preferred embodiment of the invention, the functionalized piezoelectric film further integrating at least one active agent for controlled release of the agent into a body. [00112] In one embodiment, the piezoelectric material is removable from the catheter type device; advantageously the piezoelectric material is integrated into a chip which is placed in the catheter type device. However, in another embodiment, the piezoelectric material is coated on the tubular element. This has the advantage of providing a better connection of the piezoelectric material 2/52 to the tubular element 1/51 , optionally with a substrate in between than a simple chip which is than e.g. glued on the tubular element. In addition, for many applications this improves the quality of the results or makes certain function possible. For example, the piezoelectric element in a chip could not detect the changes in surface acoustic waves with the same quality as a coated piezoelectric material 52, because of the number of border surfaces the acoustic wave has to pass. Therefore, it is advantageous that this embodiment make the use of a chip superfluous.

[00113] Changes and modifications in the specifically described

embodiments can be carried out without departing from the scope of the invention, which is intended to be limited by the scope of the appended claims.

Claims

1 . A medical device comprising:

an optical conductor (1 ) with a proximal end and a distal end and configured to conduct optical waves;

a material (2) configured to transform the optical waves conducted by the optical conductor (1 ) into mechanical waves.

2. Medical device according to claim 1 , wherein the material (2) is piezoelectric.

3. Medical device according to claim 1 or 2, wherein the material (2) is an optical fibre.

4. Medical device according to one of claims 1 to 3, wherein the material (2) is arranged at the distal end of the optical conductor (1 ).

5. Medical device according to one of claims 1 to 4, wherein the material (2) is coated on the surface of the optical conductor (1 ).

6. Medical device according to one of claims 1 to 5 comprising further an optical detector detecting the optical waves at the proximal end of the optical conductor (1 ).

7. Medical device according to claim 6 comprising at least one optical source for emitting optical waves with an activation wavelength for activating the material (2) in an activation mode and for emitting optical waves not activating the material (2) in a detection mode.

8. Medical device according to claim 6 or 7, wherein the optical detector is an optical coherent tomography.

9. Medical device according to anyone of preceding claims being a catheter further configured to inject through said catheter into a liquid ambient medium something, preferably a thrombolytic drug to emulsify occlusion or a radiographic contrast agent to facilitate visualization.

10. Medical device according to anyone of preceding claims configured to monitoring and controlling the magnitude of the acoustic vibrations induced through a feedback mechanism.

1 1 . Medical device according to anyone of preceding claims configured to control an optical source for generating the optical waves such that the maximum size of a cavitation bubble is approximately the same as the diameter of the optical conductor (1 ) and to pulse said optical waves at a repetition rate such that multiple cycles of this process generates an acoustic radiation field in a fluid around the material (2).

12. Medical device according to anyone of preceding claims comprising a light source.

13. Medical device according to anyone of preceding claims, wherein the wavelength of the optical waves emitted by the optical source is controlable.

14. Medical device according to anyone of preceding claims further comprising an irrigation channel (4).

1 5. Medical device according to anyone of preceding claims comprising a handhold (3') at the proximal end of the optical conductor (1).

16. Medical device according to anyone of preceding claims further comprising a least one membrane linked to the material (2).

17. Medical device according to anyone of preceding claims, wherein the material (2) has a thickness gradient.

18. Medical device according to anyone of preceding claims, wherein the material (2) further comprising at least one dopant specie.

19. Medical device according to anyone of preceding claims wherein the piezoelectric material is removable from the device.

20. Medical device according to anyone of preceding claims, wherein the surface of the material (2) is chemically functionalized.

21 . Medical device according to anyone of preceding claims, wherein said functionalized material (2) surface further integrating at least one active agent for controlled release.

22. A method performed by a medical device comprising:

transmitting optical waves through an optical conductor (1 ) with a proximal end and a distal end to a material (2);

transforming the optical waves absorbed at the material (2) into mechanical waves.

23. A medical device comprising:

a tubular element (51 );

a piezoelectric material on the surface of the tubular element

(51 );

an electrode on the piezoelectric material (52) for creating acoustic waves.

24. A medical device according to claim 23, wherein the piezoelectric material (52) is coated on the surface of the tubular element (51 ) and/or the electrode (53) is coated on the piezoelectric material (52).

25. A medical device according to claim 23 or 24, wherein the electrode (53) is an interdigital transducer.

26. A medical device according to anyone of claims 23 to 25, wherein the electrode is connected to an antenna (54).

27. A medical device according to anyone of claims 23 to 26 configured to detect the acoustic wave on the tubular element (51 ) and send a feedback signal on the basis of the detected acoustic wave.

28. A medical device according to claim 27, further comprising another electrode (54'), being preferably an interdigital transducer, on the piezoelectric material (52) or on another piezoelectric material (52) for detecting the acoustic wave on the tubular element (51 ).

29. A medical device according to claim 28, further comprising an antenna for sending the feedback signal.

30. A medical device according to claim 27, wherein the electrode

(54) is configured to detect the reflected acoustic wave and send the feedback signal in the same way as having the received the input signal for activating the piezoelectric material.

31 . A medical device according to anyone of claims 27 to 30 comprising a controller for analysing the feedback signal.

32. A medical device according to claim 31, wherein the controller is configured to detect a physical contact, a physical force of a contact, a physical force direction of a contact and/or a location of a contact in a strain sensing area on the tubular element on the basis of the feedback signal.

33. A medical device according to claim 32, wherein the controller determines a physical contact, a physical force of a contact, a physical force direction of a contact and/or a location of a contact in the strain sensing area on the tubular element (51 ) on the basis of the feedback signal and further feedback signals received from further electrodes (54) on the piezoelectric material (52).

34. A medical device according to claim 31 or 32, wherein the electrode(s) is/are arranged at a distal end of the tubular element (51 ).

35. A medical device according to claim 27, wherein the controller is configured to detect a chemical or biological value on the basis of the feedback signal, wherein a sensing area is chemically or biologically functionalized.

36. A medical device according to anyone of claims 23 to 35 comprising a layer over the piezoelectric material (52).

37. A method for manufacturing a medical device comprising the steps:

providing a tubular member (1 , 51 );

coating on the tubular member (1, 51) a piezoelectric material

(2, 52).

38. A method according to claim 37 comprising the step of coating an electrode (53) on the piezoelectric material (52).