Patent ID: 6939338

Claim:
An elongated medical instrument configured to be inserted into a body, comprising: an elongated instrument body having a proximal segment and a distal segment; a temperature-activated actuator coupled to the distal segment of the elongated instrument body, the actuator comprising first and second elongated actuator members extending side-by-side in substantially a common plane and each configured to move in opposite directions when independently activated; a first heating device coupled to the first elongated actuator member and configured to deliver thermal energy to the first elongated actuator member to activate the first elongated actuator member and cause the first elongated actuator member to move the distal segment in a first direction; a second heating device coupled to the second elongated actuator member and configured to deliver thermal energy to the second elongated actuator member to activate the second elongated actuator member and cause the second elongated actuator member to move the distal segment in a second direction opposed to the first direction, wherein the elongated instrument body has an instrument body axis and sidewall extending between an instrument body proximal end and an instrument body distal end, and the temperature-activated actuator is being mounted in the instrument body sidewall such that first and second elongated actuator members extend substantially parallel to the instrument body axis; and means for providing slippage between the first and second actuator members and the instrument body sidewall when the first and second actuator members are activated, wherein the slippage providing means comprises: first and second elongated sleeves formed in side-by side relation within the sidewall of the distal segment; the first sleeve formed of a material having a low coefficient of friction and dimensioned to loosely encase the first elongated actuator member, whereby the first elongated actuator member is free to move longitudinally within the sleeve as the distal segment is moved in the first or second direction; and the second sleeve formed of a material having a low coefficient of friction and dimensioned to loosely encase the second elongated actuator member, whereby the first elongated actuator member is free to move longitudinally within the sleeve as the distal segment is moved in the first or second direction.