Biomedical Engineering Reference
The following knowledge should be excluded:
1. hidden knowledge (because it is not easily accessible to a person skilled in the
2. patent applications which are still secret at the date of filing of the application
3. particularly old prior art, which should not be combined with recent prior art.
Applying the so-called Problem & Solution Approach (PSA), only the prior art
that solves the same technical problem should be considered.
The PSA is defined as follows:
• identify the closest prior art (CPA), typically and ideally consisting of a single
• check if there are technical differences between the claimed invention and the
closest prior art (if no difference is found, the invention is not new);
• identify the technical effect caused by this difference;
• infer the objective technical problem from that difference (so that the difference
is the solution to the technical problem);
• assess whether the objective problem is technical (if this condition is not met,
there is no technical breakthrough over prior art and therefore no inventive
• determine whether there are indications in the state of the art that would lead a
person skilled in the art to solve this technical problem in the same way as in
the invention (if there is any, no inventive step exists).
The closest prior art must be in the same technical field as the invention: the
choice falls on the document that describes most technical features in common or
most similar functions and/or properties.
After having identified the relevant prior art, the applicant must verify if the
documents could be combined to establish the inventive step.
The EPO applies the could/would approach : would a person skilled in the art
achieve the invention or could such person skilled in the art implement it?
Already the documents under consideration must contain the teaching to com-
bine the prior art found.
It must be pointed out that the person skilled in the art is an ideal figure: it is a
technician, with a general knowledge in the technical field of the invention, with
normal working capacity but without inventive skills. In certain cases it is a group
of researchers (in multidisciplinary fields such as nanotechnology).
The invention claims:
An alloy having composition ABC for use as a corrosion-resistant material in
devices exposed in saline environments.
Document D1 describes an alloy ABD which has good resistance to corrosion
(without specifying that it functions in saline environments). The difference is the
substitution of C with D in the alloy.