FYI The patent for the strain gauge based pointing stick (AKA "TrackPoint" from the Thinkpad series) has now expired
patents.google.com/patent/US61…
Trackpoint device
A capacitive sensor input device which includes a movable stud having a top portion for manipulation by a user and a conductive bottom portion is connected to a planar surface, such as a circuit board by means of an elastomeric, adhesive connector.patents.google.com