Go with the flow

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Case No. O2016_009 | Hearing of 29 October 2018

iFlow sensor

Please find some background information about the subject-matter at stake on this Blog here.

In brief, Hamilton Medical AG alleges infringement of its Swiss patent CH 701 755 B1 (see Swissreg for further bibliographic details) by some of imtmedical AG‘s iFlow sensors. The only independent claim 1 of the patent as granted reads as follows:

Durchflussmessfühler (10) mit einem ein zylindrisches Gehäuse (10) definierenden Durchgang mit einer ersten Durchgangsöffnung (13) und einer zweiten Durchgangsöffnung (29); einem im Durchgang des Gehäuses angeordneten Strömungswiderstand (23), welcher das Gehäuse in einen ersten und einen zweiten Gehäuseteil (11 und 27) unterteilt; einer ersten Anschlussstelle (17) mit einer Verbindung zum Innern des ersten Gehäuseteils (11); und einer zweiten Anschlussstelle (19) mit einer Verbindung zum Innern des zweiten Gehäuseteils; dadurch gekennzeichnet, dass die ersten und zweiten Anschlussstellen (17, 19) in einem Abstand voneinander auf dem gleichen Gehäuseteil angeordnet sind.

Fig. 1 of CH 701 755 B1

The defendant denies an infringment, and argues for nullity as a plea in defense.

This case is already pending for two years. Likewise, the main hearing yesterday has been quite lengthy: Plaintiff’s initial pleadings took about 2.5 hours, and defendant’s reply took yet another two hours. The hearing was not even finished thereafter, but we just could not attend any longer. Anyway, some key aspects of the case became pretty clear from both parties’ first pleadings.

In our understanding, the expert opinion of the judge-rapporteur had held that the patent as granted was not valid. However, the judge-rapporteur apparently also held that the patent would be valid in a more limited extent, and that it would still be infringed to that extent. The plaintiff had invoked the patent to that limited extent in the second part of his reply, after the instructional hearing. Defendant firmly denied that this ‘verbal limitation’ (verbale Einschränkung) was admissible and argued that the case had to be dismissed if claim 1 of the patent as granted was invalid.

UPDATE 10 February 2019:

A previous version of this post noted that the patentee invoked the patent to a more limited extent only after receipt of the expert opinion of the judge-rapporteur. This was wrong. He did so already in the second part of his reply, after the instructional hearing. This has been corrected in the above.

Further, the defendant relied on i) a prior use; and ii) US 6,585,662 when arguing for lack of an inventive step.

Fig. 8 of US 6,585,662
Uphill fight

It remains to be seen how all this turns out, but from what has been argued at the hearing we conclude that it is currently an uphill fight for the defendant. And it did not seem as if this was a case to be concluded with a settlement. Stay tuned.

Reported by Tina VOCI and Martin WILMING


Case No. O2016_009 | Hearing of 29 October 2018

Hamilton Medical AG
imtmedical AG

Panel of Judges:

  • Dr. Mark SCHWEIZER
  • Dr. Tobias BREMI
  • Dr. Lorenzo PARRINI


  • Dr. Tobias BREMI

Court Clerk:


Representative(s) of Plaintiff:

  • Dr. Christoph GASSER (BianchiSchwald)
  • Renato BOLLHALDER (Bohest), assisting in patent matters
  • Dr. Torben MÜLLER (Bohest), assisting in patent matters

Representative(s) of Defendant:

  • Dr. Rudolf RENTSCH (IPrime)
  • Ernst BREM (IPrime)
  • Joachim KÜNSCH (PPR)

CH 701 755 B1

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