Needles are among the most common used instruments in surgery by medical professionals either for diagnosing the disease such as biopsy or for medical intervention such as drug delivery. Generally, needles are assumed to be minimally invasive, however it is desirable to decrease the insertion and pulling out force in order to prevent tissue damages. The hypothesis is that reducing the resistance forces caused by needle-tissue interaction leads to less tissue damage and less pain. Bioinspired needles mimicking insect stingers have been designed to reduce this resistance force and this design could provide to a more sophisticated steering of needle. Although our earlier study on honeybee-mimicking needle has shown the reduction of insertion force by having barbs on the needle body, the pull-out force is a big concern in particular during the extraction of the needle. A special mechanism to control the barbs at the end of the insertion procedure is designed. In this study, we investigated the use of SMA to control the barb functions so that it will reduce the pull-out force of the bioinspired needles. In this work, smart barb design is proposed. Circular barbs are divided to two symmetric parts connected by a ring around the central axis of the needle and the rings are connected to form the base part of its structure. Barbs are designed to have parallel faces with a desired angle through the insertion mechanism and are connected with a SMA wire at their bottom that is connected to the rear and front part of the needle. After insertion, actuating the SMA wires force the barbs to rotate around the rings due to the torque provided by wire shrinkage. As a result, barbs have now the same angle along the movement of needle for pulling out as they have for insertion mechanism.

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