Patent ID: 6986282

Claim:
An apparatus for collecting downhole data during a drilling operation via a downhole drilling tool positioned in a wellbore, the wellbore having an annular pressure therein, the wellbore penetrating a subterranean formation having a pore pressure therein, the downhole tool adapted to pass a drilling mud flowing therethrough such that an internal pressure is created therein, the internal pressure and annular pressure generating a differential pressure therebetween, the apparatus comprising: a drill collar operatively connectable to a drill string of the drilling tool, the drill collar having a passage therein for passing the drilling mud therethrough, the drill collar having a collar opening therein extending into a pressure chamber, the pressure chamber in fluid communication with one of the passage, the wellbore and combinations thereof; a piston slidably positioned in the pressure chamber and having a rod extending therefrom into the collar opening, the piston movable to a closed position in response to an increase in differential pressure and to an open position in response to a decrease in differential pressure such that in the closed position the rod fills the opening and in the open position at least a portion of the rod is drawn into the chamber such that a cavity is formed in the opening for receiving downhole fluid; and a sensor positioned in the rod for collecting data from the downhole fluid in the cavity.