Dynamic detection and depth location of pipette tip in microinjection

As cells are injected with micro-pipettes which operated by micro manipulator under powerful microscopes, the accuracy rate and success rate of micro-injection are determined by the pipette tip location and the depth down to the surface of petri dish. In this paper, the dynamic tip detection was realized by setting regions of interest in the images, handling the regions´ images with Gaussian filter, binarizing the images with OTSU algorithm, selecting tip contour in the binarized images and traversaling all the points of the contour to get the most right point´s coordinates. Then, lower the height in the Z direction with slow and uniform speed. The tip coordinates in the X direction were compared in time to judge whether the tip was down to the surface of petri dish. The location where the tip just contacted the dish surface was defined as the depth origin which the depth location was based on. The experiment results show that using the contour recognition method could obtain accurate tip location and depth location, and the success rate is more than 80%.