Design and Characterization of a Dual-Interval Elastic Force Sensor for Robot-Assisted Microinjection

Robot-assisted microinjection has been widely implemented in the field of experimental biology research. Force perception is more accurate than visual feedback in determining the state of interaction between the micropipette and the biological sample. The existing micro-force sensors are difficult to directly combine with micropipettes to fully utilize their capabilities. This paper develops a new integrated force-sensing microinjector with both micro-force sensing and micropipette carrying functions using a symmetrical compliant guide mechanism and highly sensitive semiconductor strain gauges. Overload protection is considered in the structure design of the sensor, which is beneficial in reducing damage caused by displacement overshot due to misuse. The mechanical performance of the proposed dual-interval force sensing device is verified through theoretical derivation, simulation analysis, and experimental testing. The sensitivity, resolution, accuracy, dynamic response, stability, and repeatability of the sensor are investigated and evaluated in the established experimental platform. Finally, puncture experiments are conducted on zebrafish larvae and crab eggs using the proposed force-sensing microinjector. The results indicate that the sensor is effective in recording force signals during penetration of the sample.