A low temperature-rise and facile manipulation method for single micro objects at the air-substrate interface

Controlled pickup and release of micro objects in non-aqueous environment has large potential applications in lab-on-chip systems, biotechnology, biomedicine, and micro device fabrication, but this kind of manipulation has been scarcely reported. In this paper, a low temperature-rise and facile strategy is proposed to pick up and release single micro objects in air on a substrate. Chlorella cells, pollens, glass fibers, micro copper wires and graphene sheets at the air-substrate interface can be successfully picked up by the Van der Waals force between a stationary micro manipulation probe (MMP) and captured sample, and transported through an arbitrary 3D path in air to a desired position on the substrate by moving the device. The captured sample can be controllably released by ultrasonically exciting the MMP. The effects of working parameters such as the distance between the MMP's tip and substrate, and cross-sectional shape and size of the vibration transmission rod and MMP on the release position deviation, are investigated and design guidelines for the manipulation device are proposed. Measured temperature rise at the MMP's tip in contact with the captured sample, is lower than 0.4 °C, which makes it competitive in the manipulation of heat sensitive samples such as biological cells. (paper)