Motion capture, especially of the knee angle, is an important component for situational triggering of functional electrical stimulation (FES). One major disadvantage of commercial FES devices is their bulky design that prevents unobtrusive wearing in everyday life and limits thepatient’s free choice of appearance. This paper presents an alternative approach of sensors for motioncapture in form of textile-based strain sensors. These can be integrated in a FES system in form offunctional leggings, which make the FES system suitable for an unobtrusive daily use. Textilesensors, especially knitted sensors have already proven to be very promising to detect tensile strain.In particular, weft-knitted strain sensors, which can be integrated directly into the clothing during theknitting process, have the potential to detect the knee angle and therefore derive the gait phase due tothe bending of the limbs without disturbing the wearer unnecessarily. Different designs of the weftknittedstrain sensor and their influence on the measurement behaviour of the sensor have beeninvestigated. The weft-knitted strain sensor can be directly integrated in the knee area of the functionalleggings to be used as a soft trigger to initiate electrical impulses for FES.