Design and Experimental Evaluation of Mosquito-Inspired Needle Structure in Soft Materials

Abstract Insects steer their stingers effortlessly to a specific target and release their venom in a certain path through the skin with minimal pain. These unique traits inspire the idea to develop bioinspired needles to reduce the insertion forces and to decrease the needle path deviation (deflection) for improved targeting accuracy. Our approach in this work focus on the design of mosquito-inspired needle and evaluation of the needle performance using vibration during tissue insertion. The mosquito-inspired needle design specifically consists of maxilla-shaped and labrum-tip design. The insertion force was measured using a force sensor, which was fixed at the needle end to measure the uniaxial force of needles. The applied vibration on the needle was measured along linear axis using piezoelectric actuator with a frequency of 150 Hz and an amplitude of 5μm. The needle was inserted at a constant speed by attaching the needle to a motorized linear stage. It was observed that the insertion forces of the proposed needle design with vibration showed a reduction by 27% compared to that of a conventional needle. This reduction in insertion force means that there is decrease in tissue gel phantom damage and it was also observed that needle bending has reduced due to reduction in bending stiffness of the tissue phantom. Furthermore, the needle insertion tests in real tissues (bovine kidney) considering the proposed needle geometry and vibration will be studied in future work to understand the bioinspired needle-tissue interactions.