T 2181/17 06-04-2022

1. The invention

The invention relates to a device for introduction into a vessel or organ. The device comprises a deformable elongate body, a deflection mechanism disposed in the elongate body, at least two optical fibre contact force sensors disposed in a distal extremity of the elongate body, a storage device and processing logic.

The processing logic is programmed to apply a force-strain conversion matrix stored in the storage device to compute, from the output of the optical fibre contact force sensors, a multi-dimensional force vector corresponding to a contact force between the distal extremity and tissue wall of the organ or vessel.

Computing the forces applied to the distal extremity permits carrying out measurements or treatments while applying an optimal contact force between the distal extremity and the tissue wall. This is relevant for example in the treatment of atrial fibrillation by selective ablation, both during the preliminary mapping and treatment phases.

2. Sufficiency of disclosure

2.1 Paragraphs [0029]-[0030] of the patent specification teach that the processing logic computes a two- or three-dimensional force vector depending upon the number of optical fibre sensors employed and that three optical fibre sensors permit the computation of a three-dimensional force vector.

The person skilled in the art thus derives from the patent specification that a force vector having more than two dimensions cannot be computed if only two sensors are used. The person skilled in the art wanting to carry out the invention as defined in claim 1 would thus not envisage such an option among the large number of conceivable alternatives and would find guidance in the same paragraphs [0029]-[0030] of the patent specification towards appropriate alternatives, for example, using three sensors to compute a three-dimensional force vector. It follows that the presence of non-working embodiments is in this case of no harm (see also G 1/03, point 2.5.2 of the Reasons).

2.2 The opponent's letter dated 9 October 2018 addresses, within the discussion of the main request in section I.2, a further objection under Article 83 EPC. The Board decided not to admit this objection to the main request using its discretion under Article 13(1) RPBA 2020 in view of the following circumstances:

a) a similar objection to auxiliary request 1 was not admitted into the opposition proceedings by the Opposition Division

b) the further objection not only includes new arguments, as argued by the opponent, but also constitutes a new objection which raises new and complex factual issues

c) the opponent did not justify why this objection to the main request was only submitted at this late stage of the proceedings

2.3 It follows that the patent specification discloses the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art.

3. Added subject-matter

Basis for the processing logic being programmed to compute a "multi-dimensional vector" combined with the feature "at least two optical fiber sensors" is provided on page 7, lines 9-20 of the application as originally filed. The wording "at least a two-dimensional force vector" on page 7, lines 17-18 refers, in the context of the application as filed, to a force vector having at least two dimensions. It is thus equivalent to the term "multi-dimensional force vector" in claim 1. The fact that a later passage on page 8, lines 7-14 describes the dependency between the number of sensors and the dimensionality of the force vector computed has no impact on the disclosure of page 7, lines 9-20.

It follows that claim 1 does not include added subject-matter.

4. Novelty

4.1 Novelty over D5

It was disputed whether and to what extent the priority claimed from document D3 was valid and, in consequence, whether and to what extent D5 belonged to the state of the art within the meaning of Article 54(3) EPC.

In this case, in light of decision G 1/15, D5 belongs to the state of the art in accordance with Article 54(3) EPC if and to the extent which the priority claimed from D3 is not valid.

D3 and D5 disclose the same technical content. Hence, D5 cannot disclose any subject-matter for which the priority from D3 is not valid. It follows that, irrespective of the extent of validity of the priority claimed from D3 and thus irrespective of the precise disclosure of D3/D5, D5 cannot destroy the novelty of claim 1 (see also T 2387/13, point 2.1.1).

4.2 Novelty over D6

D6 addresses the problem of providing tactile feedback to the surgeon during minimally invasive robotic surgery (see page 447, right column, second paragraph). D6 discloses a sensor using three optical fibre contact force sensors, the sensor being designed to be mounted at the tip of a 5 mm diameter instrument driver, in front of two bending degrees of freedom (see D6, Figure 5 and section 3.1 on page 450). The sensor and the instrument driver on which it is to be mounted each comprise an internal channel through which surgical instruments can be inserted. D6 refers to D12 for the instrument driver, so it is appropriate to construe the instrument driver of D6 taking into account the disclosure of D12.

In the instrument driver of D6/D12, the "distal extremity" within the meaning of claim 1 is defined by the tip of the instrument driver, that is, the part after the bending degrees of freedom where the sensor is to be mounted. The sensor of D6 is intended to measure the forces acting at the tip of a surgical instrument to be inserted through the internal channel of the instrument driver (see D6, last sentence of section 3.1 on page 450). This is why the sensor calibration in D6 is done having a 15 mm rod fixed to the tip acting as lever for applying torque, 15 mm being the distance between the tip of the surgical instrument and the sensor front (see the first two sentences of section 5 on pages 453-454).

Hence, the sensor of D6 is not calibrated by subjecting the distal extremity of the instrument driver to known forces but by applying the forces to the added rod. This results in a different calibration matrix because the torque resulting at the sensor's position, and thus the measurements obtained by the sensor, are different when the force is applied at the two different locations.

Consequently, the processing logic of D6 is not programmed to compute a force vector corresponding to a contact force between the distal extremity and the tissue wall but instead to compute a force vector corresponding to a contact force between a surgical instrument - located further distally than the distal extremity of the instrument driver - and the tissue wall.

It follows that D6 does not disclose the feature "at least two optical fiber contact force sensors ... configured for resolution of a multi-dimensional force vector corresponding to a contact force between the distal extremity and tissue wall of the organ or vessel ... by means of processing logic" (emphasis added by the Board). Hence, the subject-matter of claim 1 is novel over D6.

5. Inventive step

5.1 Inventive step in view of D6 and common general knowledge or D13

5.1.1 The technical effect and technical problem submitted by the opponent related to reducing complications due to tissue damage during the introduction of the device of D6/D12.

It is correct that what D6 refers to as an "instrument driver" is named an "[e]ndoscope arm" in the legend of Figure 11 of D12 and, according to the title of D12, it is made for "endoscopic robot surgery". While it is known that the displacement of an endoscope within a body passageway may cause complications due to excessive pressure on the tissue and may even lead to tissue perforation, this cannot be extrapolated to the situation for which the instrument driver/endoscope arm of D6/D12 is envisaged, as explained below.

The instrument driver of D6/D12 is used in minimally invasive robotic surgery. It is inserted in a linear motion through a trocar towards the relevant organ in a set-up comparable to that of Figure 1 of D12.

It is not disclosed in D6/D12 whether a surgical instrument is already in place within the inner channel of the instrument driver during insertion of the instrument driver into the body. Even if, as argued by the opponent, the instrument driver was inserted into the body before inserting the surgical instrument into its inner channel, there is no suggestion in D6/D12 that the insertion of the instrument driver would involve complications, nor is there any reason to assume this. The instrument driver requires no contact with the tissue before the surgical instrument is inserted in its inner channel, so that a mere forward motion performed with the minimal care to be expected during surgery would suffice to bring it through the trocar without complications.

Moreover, the patent specification and D6 are both concerned with determining the contact force after insertion of the device into the body, once the catheter (patent specification) or instrument driver/endoscope arm (D6/D12) are already at the relevant tissue/organ and interacting with it.

Hence, neither is the distinguishing feature associated with the technical effect of reducing complications during insertion of the device, nor would the person skilled in the art starting from the instrument driver/endoscope arm of D6/D12 envisage the problem submitted by the opponent. Thus, the submitted objection is not convincing.

5.1.2 As to the combination of D6 and D13, the opponent argued that the problem solved by the distinguishing feature would be to provide an endoscope which improves endoscope positioning and is suitable for therapies including contact forces.

This submission disregards that when using the instrument driver of D6/D12, no contact between the instrument driver and the tissue wall is needed or sought. Hence, the contact force between the instrument driver and the tissue wall is irrelevant for positioning and therapy. Relevant for the minimally invasive surgery for which the instrument driver of D6/D12 is envisaged is instead the force between the surgical instrument inserted in the inner channel of the instrument driver and the tissue wall (see D6, page 447, right column, second paragraph). Hence, the person skilled in the art starting from D6 would not be faced with this problem either.

5.1.3 The distinguishing feature is related instead to the different design and intended use of the devices of the invention and D6/D12. The part of the device which has to interact with the patient's tissue and for which the contact force is to be determined is different in each case. In the claimed invention, it is the distal extremity of the elongate body, while in D6/D12 it is a surgical instrument to be introduced through the inner channel of the instrument driver and which will stick out of the instrument driver's distal extremity.

The person skilled in the art starting from the instrument driver for minimally invasive surgery disclosed in D6/D12 would not reach the subject-matter of claim 1 without changing the design and intended use of the instrument driver, which would then serve a different purpose and not be an instrument driver anymore. Such fundamental changes to the intended purpose and use are, in the absence of any prompt in the prior art, not conceivable without use of inventive skill.

5.1.4 It follows that the subject-matter of claim 1 is inventive in view of D6 and common general knowledge or D13.

5.2 Inventive step in view of D7 and common general knowledge or D8

5.2.1 D7 discloses an elongated flexible member such as the insertion tube of an endoscope in which a sensor cable with two pairs of fibre Bragg gratings strands is inserted for detection of three-dimensional shapes of the insertion tube (see Figures 6 and 7 as well as paragraphs [0008]-[0009] and [0032]-[0034] of D7).

It is common ground that D7 does not disclose at least a processing logic programmed to apply a force-strain conversion matrix to compute a multi-dimensional force vector corresponding to a contact force between the distal extremity and the tissue wall of the organ or vessel (see the last feature of claim 1 in view of the definition of the multi-dimensional force vector given earlier in claim 1).

5.2.2 The person skilled in the art starting from the device of D7, if faced with the problem submitted by the opponent of providing an endoscope which can be accurately monitored to avoid tissue damage and complications, would find no suggestion in D7 to measure the contact force between the distal extremity of the insertion tube and the tissue. Let alone to compute this contact force as a multi-dimensional vector using the output provided by the sensor cable included in the device of D7.

The opponent submitted that D13 reflected common general knowledge on the relevance of the contact force at the distal end for reducing tissue damage. However, if in view of such common general knowledge the person skilled in the art starting from D7 considered the measurement of the contact force at the distal end, they would find no suggestion in D7 or using common general knowledge to use the sensor cable employed for shape sensing in D7 to determine the contact force at the distal end of the insertion tube.

It is correct that D8 employs the same sensor technology, i.e. fibre Bragg gratings strain sensors, to measure forces. However, D8 does this for controlling industrial robots in electromagnetically noisy environments (see Abstract and Introduction). D8 can thus not be regarded as common general knowledge in the field of endoscopic tubes. The person skilled in the art starting from D7 and faced with the problem above would not consult D8 either. D8 is in a remote technical field and does not deal with the same problem. Moreover, although the underlying sensor technology is the same, the sensor taught in D8 differs from that of D7 not only in its use but also in its construction. D8 emphasises that the fibre Bragg gratings must be properly fixed by uniformly gluing them (see D8: page 2, left column, second paragraph and section 4). In contrast, the sensor cable in D7 cannot be glued without a major redesign because it is made to be slidably inserted through the biopsy channel of the insertion tube/endoscope (see paragraph [0033] of D7).

5.2.3 Hence, the objections of lack of inventive step in view of D7 and common general knowledge or D8 are not convincing.

5.3 Inventive step in view of D9 and D8

The objection of lack of inventive step in view of D9 and D8 was raised in the opponent's statement of grounds of appeal by reference to the notice of opposition.

The arguments in the notice of opposition are directed to claim 1 as granted. Hence, the submission disregards the amendments to claim 1 of the main request as compared to claim 1 as granted. Moreover, the impugned decision gives reasons under point 3.3.3 why the inventive-step objection to claim 1 of the auxiliary request 1 in view of D9 and D8 was not found convincing by the Opposition Division. The reasons provided likewise apply to claim 1 of the main request. The opponent did not explain why it considered this part of the decision to be incorrect. Therefore, this objection does not meet the requirements set out in Article 12(2) RPBA 2007. It is thus not taken into account by the Board under Article 12(2) and (4) RPBA 2007.

5.4 Inventive step starting from D10

In the statement of grounds of appeal, the opponent also raised an objection of lack of inventive step over the combination of D10 and D8 by reference to the notice of opposition. However, as pointed out by the Board in its communication of 28 July 2021 and not disputed by the opponent, this submission disregards the amendments to claim 1 of the main request as compared to claim 1 as granted, so it does not satisfy the requirements of Article 12(2) RPBA 2007. It is thus not taken into account under Article 12(2) and (4) RPBA 2007.

A detailed objection of lack of inventive step starting from D10 and referring to D8 and D6 was submitted by the opponent in the letter of 13 January 2022, after notification of the summons to oral proceedings. However, as pointed out by the proprietor in the letter of 4 February 2022 and not disputed by the opponent, this constitutes an amendment to the

opponent's case in appeal. Since no cogent reasons justifying exceptional circumstances have been provided, this objection is not admitted into the proceedings (Article 13(2) RPBA 2020).

5.5 Inventive step in view of D11, D13 and common general knowledge

D11 deals with determining the bending and shape of a catheter using optical fibre sensors and thus deriving the position and orientation of the catheter.

It is common ground that D11 fails to disclose at least a deflection mechanism as defined in claim 1 as well as the same feature not disclosed in D7, i.e. a processing logic programmed to apply a force-strain conversion matrix to compute a multi-dimensional force vector corresponding to a contact force between the distal extremity and tissue wall of the organ or vessel.

As regards the latter feature, the disclosure of D11 is comparable to that of D7 in that fibre Bragg gratings are also used in D11 to determine the shape of the catheter but not the contact force at the distal extremity. Hence, as indicated by the Board in its communication and not disputed by the opponent, this objection suffers from the same issues indicated for the objection starting from D7. Therefore, this objection is not convincing either.

6. It follows that none of the objections prejudices the maintenance of the patent on the basis of the main request.