Studies With SMA Actuated Needle for Steering Within Tissue

Flexible needles that can be steered within soft tissues are a promising approach to precisely reach target locations, thereby can significantly benefit needle based surgical procedures such as brachytherapy and biopsy. Several design approaches have been suggested to increase needle flexibility that include bevel-tip needles, kinked needles and flexure-based needles. These needles when inserted into a soft materials takes a curved path. This curved path can be controlled while inserting by rotating the needle at its base. In this work another approach to control the curved path was explored. Here the needle body was attached with a shape memory alloy (SMA) actuator close the needle tip that when actuated bends the needle and thereby leads to a curved path inside soft tissue. A prototype of the SMA actuated needle was developed and the working principle was demonstrated in air, tissue-mimicking gel, and pig liver. Moreover, the effect of actuator wire diameter on the needle behavior were studied.