Research On Piezo-driven Microinjection Technology

Microinjection technique has attracted extensive attention in many fields since thedevelopment of modern biotechnology. Microinjection systems has low level ofautomation and poor controllability, especially, applying the piezoelectric microinjectionsystem with actuators of low bandwidth and poor carrying capacity, mercury need to beadded in the micropipette during the injection process, which calls for high requirementson the environment and easily does harm to the operator. So it is both theoretically andpractically important to promote the technology of microinjection in order to improvethe development of biomedical engineering.In the first step, according to the requirements of the piezoelectric microinjection,MP-285as holding manipulator, MX7600R as injection manipulator, Harvard PHD Ultraprecision syringe pumps, NIKON company TI series biological inverted optical micro-scope and A601f series8bit CCD camera were selected to set up microinjection system.PST150/4/20VS9piezoelectric ceramic was applied after vibration test, connector betweenthe piezoelectric ceramic and micro syringe needle was designed.In the second step, Research on the driving technology of piezoelectric micro-injection system by analyzing the load characteristics of piezoelectric ceramics, phase lagcaused by the piezoelectric ceramic was calibrated using zero compensation, lag-phase andlead controller. Driving power supply based on PA92was designed for the piezoelectricmicroinjection system. While tested to be of44.293degree phase margin, up to20kHzeffective bandwidth, up to150V output, the power supply experimentally meet therequirements of stability and high dynamic for the microinjection system.In connection with output displacement of piezoelectric ceramic could not meet therequirements of microinjection, a complex injection method using the micromanipulatorwas proposed with appropriate displacement compensation of the micropipette. To improvethe level of automation of the system, visual servo control method based on image wasapplied which could result in automatic micromanipulator control as well as microinjectiontool and target cell recognition.Finally, the rupture and injection process of mouse oocyte was successfully performed using automated piezoelectric microinjection system. Through the comparison test, the bestparameters to pierce the egg zona pellucida of the mice oocyte were: the triangular wave ofVpp45V, frequency60Hz and of90%symmetry; optimal parameters for membranepuncturing: a Vpp of15V, frequency of50Hz, symmetric of90%triangular wave.Meanwhile, by combining the actuating system and the piezoelectric micro-syringe, theinjection process can also be completed without mercury. Subsequently, the requirementsof the operating environment were reduced, and the system was more safety to manipulatewith less harm to the operator.