Needle Puncture

A wide range of medical applications require insertion of needles and microneedles into biological tissue. We explore the dynamic insertion of hollow needles into elastomeric samples. Prior to puncture, the needle indents the material to accumulate critical strain energy. We use a double-insertion method, where the needle is inserted and re-inserted at the same location, to estimate the fracture properties of the material. We quantify the displacements of the needle, the free surface of the specimen and depth of insertion of the needle through high-speed image analysis to estimate the contributions to the resisting force against needle penetration at each stage of the process. We estimate that the toughness of our silicone samples increases with needle velocity (i.e., with strain rate).

  • P. Shrestha, C. Geffner, M. Jaffey, Z. Wu, M. Iapichino, B. Stoeber, “Mechanics of needle insertion into soft solids: Force modeling and fracture toughness estimation,” Proceedings of the 7th International Conference on Microneedles, Seattle, WA, U.S.A., May 15-17, 2023.
  • S. A. Ranamukhaarachchi, B. Stoeber, “Determining the factors affecting dynamic insertion of microneedles into skin,” Biomedical Microdevices, vol. 21, art. 100, 2019.