An endoscopic bipolar forceps includes a housing and a shaft, the shaft having an end effector assembly at its distal end. Each pair of said hybridization probes consists of a FRET donor probe carrying a FRET donor moiety and a FRET acceptor probe carrying a FRET acceptor moiety having an emission maximum between 550 and 710 nm. A centrally aligned hole is positioned close to the front edge of the blade member. The method also involves coupling a tuning capacitor with the crystal oscillator circuit, and coupling the digitally-modulated output signal from the digital modulator to the crystal oscillator circuit and the tuning capacitor. A piston, inserted in the columnar space and brought into contact with the functional end face, separates the intermediate pressure section from the bypass channel when the piston contacts the functional end face. To this end the system comprises in particular a cavity resonator.