Towards the design and development of an active needle for therapeutic procedures

The accuracy of many needle-based therapeutic procedures depends on the placement of the needle tip to desired locations. In many of these procedures, lack of actuation and dexterity of the device limits the surgeon´s capability to compensate for the probable errors. To overcome these limitations shape memory alloy (SMA) wire actuators were attached to the needle body to provide contraction forces to bend the needle tip. In this paper a miniature prototype of a SMA activated needle was designed and developed. To obtain an enhanced deflection a flexure element was included in the design. A shape memory polymer (SMP) was used as the flexure component to provide dexterity and to electrically insulate the two segments of our needle. The SMP´s properties to recover its initial shape, upon applying heat above its glass transition temperature, was utilized to bring the device back to its original configuration after each time of activation.