Human adiposexe2x80x93derived mesenchymal stem cellxe2x80x93based medical microrobot system for knee cartilage regeneration in vivo Targeted cell delivery by a magnetically actuated microrobot with a porous structure is a promising technique to enhance the low targeting efficiency of mesenchymal stem cell (MSC) in tissue regeneration. However, the relevant research performed to date is only in its proofofconcept stage. To use the microrobot in a clinical stage, biocompatibility and biodegradation materials should be considered in the microrobot, and its efficacy needs to be verified using an in vivo model. In this study, we propose a human adiposexe2x80x93derived MSCxe2x80x93based medical microrobot system for knee cartilage regeneration and present an in vivo trial to verify the efficacy of the microrobot using the cartilage defect model. The microrobot system consists of a microrobot body capable of supporting MSCs, an electromagnetic actuation system for threedimensional targeting of the microrobot, and a magnet for fixation of the microrobot to the damaged cartilage. Each component was designed and fabricated considering the accessibility of the patient and medical staff, as well as clinical safety. The efficacy of the microrobot system was then assessed in the cartilage defect model of rabbit knee with the aim to obtain clinical trial approval.

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.