Fabrication of an electro-thermal micro-gripper with elliptical cross-sections using silver-nickel composite ink

• A fabrication method for thick electro-thermal structures is proposed.
• Due to cross-sectional area difference of the cold and hot arms, the micro-gripper can be driven by applying dc voltages.
• The electrical and mechanical behaviors of the micro gripper are well characterized.
• The fabricated micro gripper can successfully grip a small ball with a diameter of 1.3 mm.

This paper proposes a rapid fabrication process for miniaturized electro-thermal grippers by using silver-nickel composite ink. Thick resistive structures are dispensed on a silicon wafer by a dispenser, and the parameters of the dispenser can be controlled for different thicknesses of hot and cold arms in a micro-gripper. The fabricated single layer structures are almost symmetric about a central plane of symmetry, thus largely suppressing the out-of-plane deflection. Due to cross-sectional area difference of the cold and hot arms, the micro-gripper can be driven by applying dc voltages. Electrical and mechanical behaviors of the micro-grippers are simulated and tested, and the simulation results are in accordance with the experiment results. The simulated maximum temperature is 155 °C, and occurs at the hot arms with an input voltage of 1.54 V. The measured displacement of the micro-gripper is observed to be 311 μm for an applied current of 0.26 A with maximum power dissipation of 0.4 W. The fabricated micro-gripper can grip a small styrofoam ball with a diameter of 1.3 mm between both tips.