A robotic system for investigation on mis-alignment force of needle and vein needle insertion into blood vessel

Venipuncture is one of the most routine medical procedure, it is crucial to realize high precision and high success rate of venipuncture needle insertion. Being the first and fundamental step for higher needle insertion precision, investigation of force of needle insertion into soft tissue should be studied. Existing investigations on venipuncture needle insertion blood vessel addressed the ideal case, i.e., the axis of venipuncture needle is co-planed with the axis of target vein. While in practical, this precise case seldom occurs, that's to say, there exists error, more or less, between the axes of vein and needle. In this paper, the study is concentrated on experimentally study the nonideal or practical case, i.e., mis-alignment between two axes of vein and needle shaft. First, an experimental platform is setup which is designed with 5 degrees of freedom and the venipuncture needle is driven by a translational motion with three more translational degree of freedom to move the needle to the vein. Then, a series of experiments are implemented with adjusting angle between axis of needle and that of vein and the pitch angle of needle axis. The insertion force is recorded and it is different from that of the co-planed case which is investigated before this study. This study, for the first time, presents the experimental results for the case, and it is helpful to identify the mis-alignment of the needle and vein.