Needle-based medical device with needle shield

A medical device comprising:

• a housing;
• a needle fixed relative to the housing, the needle having a sharp tip and a needle axis;
• a needle shield assembly comprising:
• a needle shield having a proximal end and a distal end, the needle shield being moveable relative to the housing, and coaxial with the needle axis, the distal end of the needle shield comprising one or more steps;
• a biasing member providing a biasing force to the needle shield, such that the biasing force can move the needle shield parallel to the needle axis in a distal direction relative to the housing;
• an actuator for selectively restraining the needle shield when the needle shield is in a non-shielding position and releasing the needle shield so that the needle shield can move from the non-shielding position to a shielding position in which the needle shield covers the sharp tip;
• a needle blocking object moveable from a non-blocking position, when the needle shield is in the non-shielding position, to a blocking position in which the blocking object prevents the sharp tip from exiting the needle shield, when the needle shield is in the shielding position;
• a carrier having a nest for carrying the needle blocking object when the needle shield moves from the non-shielding position to the shielding position and for maintaining the needle blocking object in contact with the needle when the needle shield is in the non-shielding position and in the blocking position when the needle shield is in the shielding position;
• and wherein, when the needle shield is in a non-shielding position, the needle blocking object is maintained against one of said steps.

For use in a needle based medical device having a needle with an axis and a sharp distal tip, a method of shielding the sharp distal tip comprising the steps of:

• providing a housing;
• providing a needle shield having a proximal end and a distal end, the needle shield being moveable relative to the housing, and coaxial with the needle axis, from a non-shielding position into a shielding position in which the sharp distal tip is covered;
• providing a biasing member exerting a biasing force on the needle shield, such that the biasing force can move the needle shield parallel to the needle axis in a distal direction relative to the housing;
• providing an actuator for selectively restraining the needle shield when the needle shield is in a non-shielding position and releasing the needle shield;
• providing a needle blocking object and a carrier with a nest for the needle blocking object, such that the needle blocking object is moveable from a non-blocking position, when the needle shield is in the non-shielding position, to a blocking position in which the blocking object prevents the sharp tip from exiting the needle shield, when the needle shield is in the shielding position;
• inserting the sharp distal tip into a patient;
• actuating the actuator so that the needle shield is released;
• removing the sharp distal tip from the patient, such that the needle shield moves, with the biasing force, from the non-shielding position to the shielding position.