A medical puncturing device, comprising: a housing having a proximal end and a distal end, the housing comprising at least one flexure member extending internally therein; a shield having a proximal end and a distal end, the shield proximal end disposed within the housing, and the shield axially movable relative to the housing; a skin puncturing assembly disposed within the housing and comprising a movable carrier and a skin puncturing element integral with the carrier, a distal end of the skin puncturing element adapted for puncturing the skin of a patient, the carrier movable from a retracted position wherein the distal end of the skin puncturing element is disposed within the shield to a puncturing position wherein the distal end is exposed from the shield to puncture the skin of the patient, the carrier maintained in the retracted position by engagement of the at least one flexure member with the carrier and moved from the retracted position to the puncturing position upon release of the at least one flexure member from the carrier; a drive spring disposed within the housing, the drive spring adapted to move the carrier from the retracted position to the puncturing position upon release of the at least one flexure member from the carrier; and a retraction spring adapted to return the carrier to a position within the housing wherein the shield encompasses the skin puncturing element after the carrier reaches the puncturing position, wherein the at least one flexure member defines a camming surface and the shield defines an opposing camming surface, wherein axial displacement of the shield into the housing causes the opposing camming surfaces to engage and release the at least one flexure member from the carrier, characterized in that the retraction spring is disposed within the movable shield, so as to be compressed between the carrier and the shield. a housing having a proximal end and a distal end, the housing comprising at least one flexure member extending internally therein; a shield having a proximal end and a distal end, the shield proximal end disposed within the housing, and the shield axially movable relative to the housing; a skin puncturing assembly disposed within the housing and comprising a movable carrier and a skin puncturing element integral with the carrier, a distal end of the skin puncturing element adapted for puncturing the skin of a patient, the carrier movable from a retracted position wherein the distal end of the skin puncturing element is disposed within the shield to a puncturing position wherein the distal end is exposed from the shield to puncture the skin of the patient, the carrier maintained in the retracted position by engagement of the at least one flexure member with the carrier and moved from the retracted position to the puncturing position upon release of the at least one flexure member from the carrier; a drive spring disposed within the housing, the drive spring adapted to move the carrier from the retracted position to the puncturing position upon release of the at least one flexure member from the carrier; and a retraction spring adapted to return the carrier to a position within the housing wherein the shield encompasses the skin puncturing element after the carrier reaches the puncturing position, wherein the at least one flexure member defines a camming surface and the shield defines an opposing camming surface, wherein axial displacement of the shield into the housing causes the opposing camming surfaces to engage and release the at least one flexure member from the carrier, characterized in that the retraction spring is disposed within the movable shield, so as to be compressed between the carrier and the shield.