Viable cell handling with high aspect ratio polymer chopstick gripper mounted on a nano precision manipulator

This paper presents the development of an optimized contact technique for viable cell manipulation utilizing a high aspect ratio polymer chopstick gripper. The gripper consists of a 2 μm thick metal heater layer and a 60 μm thick SU-8 layer and is fabricated by a typical UV-LIGA process using SiO₂ as sacrificial layer. The grippers were completely released, de-tethered and assembled as end-effectors on to a nano precision manipulator to perform cell manipulation. Successful pick-and-place of a suspended normal rat kidney cell in phosphate buffered saline solution was demonstrated. The major cell-damage mechanisms associated with contact techniques were identified and alleviated by optimizing the handling force and operating temperature of the polymer gripper. The viability of cells handled with this optimized contact technique was demonstrated by labeling cells with a fluorescent dye. The developed technique will enable incorporation of simple, viable, and repeatable cell handling capabilities into the generic micromanipulators used in the biological laboratories.