Medical devices and methods incorporating frustrated total internal reflection for energy-efficient sealing and cutting of tissue using light energy

An optical-based tissue-sealing system, comprising:

• a housing;
• an end effector assembly operably connected to the housing, the end effector assembly including:
• a first jaw member having a tissue-contacting surface;
• and
• a second jaw member movably coupled to the first jaw member, the first jaw member and the second jaw member cooperating to grasp tissue between the first jaw member and the second jaw member;
• a light source that provides a light beam for sealing tissue, the light source directed at the tissue-contacting surface of the first jaw member and optically coupled to the tissue-contacting surface to direct the light beam toward the tissue contacting surface of the first jaw member at a predetermined angle of incidence with respect to an axis perpendicular to the tissue contacting surface of the first jaw member, the predetermined angle of incidence configured to provide total internal reflection of the light beam from any point along an interface between the tissue-contacting surface of the first jaw member and air, and to impede the light beam from transmission through the interface when tissue is not grasped between the first jaw member and the second jaw member, and the predetermined angle of incidence configured to provide transmission of at least a portion of the light beam through a portion of the tissue-contacting surface of the first jaw member that is in contact with the tissue when the tissue is grasped between the first jaw member and the second jaw member;
• and
• a controller coupled to the light source, the controller configured to control at least one parameter of the light beam.

A method of treating tissue with an optical energy-based medical instrument, comprising:

• directing a light beam into an optical element of a first jaw member of an optical energy-based instrument and toward a tissue contacting surface of the optical element at a predetermined angle of incidence with respect to an axis perpendicular to the tissue contacting surface of the optical element, the light beam provided by a light source directed at the tissue-contacting surface of the optical element of the first jaw member;
• totally internally reflecting the light beam within the optical element from any point along an interface between the tissue-contacting surface of the optical element and a media having a low index of refraction, and impeding the light beam from transmission through the interface when tissue is not grasped between the first jaw member and a second jaw member;
• grasping tissue between the first jaw member and the second jaw member of the optical energy-based medical instrument;
• and
• transmitting at least a portion of the light beam through a portion of the tissue-contacting surface of the optical element to the tissue when the tissue is grasped between the first jaw member and the second jaw member.