An exemplary method and circuit for sensing bi-directional current through a resistive element comprises a sampling unit, a charge transfer unit, and an amplifier. By adding isocyanatosilanes the mechanical properties of the vulcanisates, in particular the elongation properties and the abrasion resistance, are improved without the difference in rebound resilience at 70 C. The entire rigid transport line including its ends is immersed in the sea at a depth which is greater than the turbulent zone of the sea. Related applications include the formation of vertical cavity surface emitting lasers on non-GaAs substrates and on GaAs substrates.