US Patent 7651478 Surgical access device with floating gel seal

A trocar is provided with a cannula and a housing and valve assembly disposed in the housing which forms a housing seal, and instrument seal, and in some cases a zero seal. A gel material is included in the valve and provides the valve with superior flotation properties for maintaining the instrument seal even when the instrument is moved off-axis. In order to accommodate movement of the gel material, voids can be formed within the valve housing and even within the gel material.