Reduced penetration force through ultrasound activation of a standard needle: An experimental and computational study

Needle insertion in soft tissue has attracted considerable attention in recent years because of its applications in minimally invasive percutaneous procedures such as cancer biopsy and regional anaesthesia. Tissue deformation and needle deflection contingent on needle penetration force are common reasons behind needle placement errors, leading to missampling in biopsy, incomplete anaesthesia, and possible post-operative morbidity. In this paper, we report the design of an ultrasonic device, based on a piezoelectric transducer with a sandwich structure, to reduce the standard needle´s penetration force and deflection. Experimental trials were carried out on brain-mimicking phantom and ex vivo porcine tissue. The results show that a standard needle with ultrasound actuation can achieve force reduction by 34.5% and deflection reduction by 38.3%. In addition, numerical simulation of static and dynamic forces was conducted. A comparison between experimental and computational results demonstrates very close agreement. All the experimental and computational results suggest success in the proposed ultrasonic device´s ability to perform accurate biopsy and regional anaesthesia.