Vibration Analysis of U-Shaped Beam Electrothermal Microactuators
This paper presents an analytical model for the vibration analysis of a U-shaped electrothermal microactuators. A U-shaped electrothermal microactuator has a unique geometrical structure which consist of, interconnected multiple thick and thin beam segments. In this proposed model, both the longitudinal and lateral deflections of each beam segment are incorporated. To facilitate the modelling process, a thick beam is replaced by the thin beam segment using the artificial Young's modulus and density so that the deformation and inertia force of the thin beam can be used to equivalently describe that of the thick beam segment. The relationship of the force and deflections in both longitudinal and lateral directions at connected points between adjacent beam segments is formulated with continuity conditions. The frequency equation is then established subjected to two both boundary and continuity conditions. Solving the frequency equation yields the natural frequencies of the U-shaped beam actuator. The analytical results are compared with the finiteelement simulation results using ANSYS software. A good agreement is observed between analytical and simulation data, and hence the proposed vibration analysis model is verified. This model provides the first insight study on the vibration analysis of U-shaped electrothermal actuators, which is essentially crucial to dynamic system modelling, control, and dimension optimizations.
Automated manipulation of zebrafish embryos using an electrothermal microgripper
We present the first report on automated micro-manipulation of zebrafish embryos using an electrothermally-actuated microgripper. A five-bar linkage compliant microgripper, driven by a V-shaped electrothermal micro-actuator, is designed based on topological optimization. The electrothermally-actuated microgripper is fabricated, tested, and then integrated into a robotic micromanipulation system. The semi-automated manipulation of a single zebrafish embryo, as well as a series of comparison experiments, is carried out. Experimental results demonstrate that the microgripper has reliable capability of picking, moving, holding and releasing the zebrafish embryo. Specifically, it performs fairly well in immobilizing and limiting the excessive deformation of the embryo. Finally, based on teaching, the whole process of zebrafish embryo microinjection is programed and performed automatically, thus demonstrating great strengths and performance of the microgripper in zebrafish embryo micro-manipulation.
A Compact Manually Actuated Micromanipulator
This letter reports a compact, versatile, and user-friendly micromanipulator that uses an elastically deformable silicon microtweezer to grab microentities, and a micrometer head for rotational manual actuation. The micro-/macroconnection is achieved via a graphite interface that results in a compact and portable design and placement on most translation stages. The system which can operate in both air and liquid, and transport objects between the two media, has a wide range of applications. We demonstrate but a few of them, including in situ construction of microstructures in 3-D, isolation and placement of individual microparticles on designated spots on sensors, on-demand microcontact printing of microparticles, and manipulation of live stem cell spheres.