Design and Testing of a New Cell Microinjector Based on SmallStiffness Mechanism * Cell microinjection is extremely crucial in biomedical domain. Currently, cell miciroinjection is mostly operated by manual method and positionbased robotic method. However, the success rate and survival rate of the injected cells are relatively low. Forceassisted robotic cell microinjection can provide force feedback and protect the cells from excessive force. In this paper, a new cell microinjector with novel smallstiffness mechanism is proposed. The smallstiffness property is achieved by combining together a constantforce mechanism and smallstiffness mechanism with force intercept. The constantforce mechanism is used to offset the force intercept of the smallstiffness mechanism when the constantforce mechanism works at constantforce range. The constantforce mechanism is modeled, simulated, optimized, fabricated and calibrated. Results show that the designed constantforce mechanism can offset the intercept force well, because the variation of constantforce value is under 0.1 N during more than 1 mm constantforce motion range. The combined lowstiffness mechanism (without force intercept) can serve as an extremely sensitive force sensor for cell microinjection application.

Automated MacroMicro Manipulation for Robotic Microinjection with Computer Vision Extensive research efforts have been made toward automating the microinjection of biological cells by leveraging microrobotic technologies. However, to best knowledge of the authors, there is no report on the automation of the timeconsuming process: moving the injection tools (a micropipette, a grippers, etc.) and cells into the field of view (FOV) of microscope from the macro FOV(outside the microscopic FOV). This paper presents a novel macromicro conversion strategy, and a grid detection and positioning algorithm to automate the timeconsuming step of moving the injection tools and cells to the microscopic FOV. The proposed solution can free the technician from the laborious handeye coordination operations for moving the injection tools and cells to the target position within the microscopic FOV. Furthermore, this paper proposes an autofocusing algorithm to automate the operation step: moving down the gripper from the air outside the culture media and then precisely clamping a cell in the liquid environment for injection. In the proposed solution, the active windowbased autofocusing algorithm is developed to solve the challenging problem: the image information is lost due to the xe2x80x9cviscous effectxe2x80x9d taking place when the gripper jaw touches the water surface. The proposed solutions are tested and validated by the microinjection experiments of zebrafish embryos using the inhouse develop microrobotic system. The technologies and strategies proposed in this paper significantly improve the automation level of the cell microinjections, and can be easily extended to any other micromanipulation of biological cells.