A safety needle device (6) includes a housing including a passageway with a needle cannula (7) extending therefrom. A shielding member (15) is movable between a first position in which a puncture tip of the needle cannula is exposed therefrom and a second position in which the puncture tip of the needle cannula is encompassed therein. The shielding member is maintained in the first position against a biasing force (9) which biases the shielding member toward the second position. A fluid and/or temperature activation material (57), such as a hydrogel or a compressed sponge, is associated with the shielding member and is adapted to deform upon contact with a fluid medium and/or a certain temperature or temperature range. Fluid flowing through the needle cannula, such as blood flow during a blood collection procedure, causes the activation material to deform, such as through expansion, thereby releasing the shielding member from the first position and allowing the drive member to bias the shielding member toward the second position.
