A Laser Driven Microrobot for Thermal Stimulation of Single Cells.

Here, we present the Thermally Activated Cell-Signal Imaging (TACSI) microrobot, capable of photothermal actuation, sensing, and light-driven locomotion. The plasmonic soft microrobot is specifically designed for thermal stimulation of mammalian cells to investigate cell behavior under heat active conditions. Due to the integrated thermosensitive fluorescence probe, Rhodamine-B, our system allows dynamic measurement of induced temperature changes. TACSI microrobots show excellent biocompatibility over 72 hours in vitro, and they are capable of thermally activating single cells to cell clusters. Locomotion in a 3D workspace is achieved by relying on thermophoretic convection, and microrobot speed is controlled within a range of 5 to 65 μm s -1 . In addition, light-driven actuation enables spatiotemporal control of the microrobot temperature up to a maximum of 60°C. Using TACSI microrobots, we target single cells within a large population, and demonstrate thermal cell stimulation using calcium signaling as a biological output. Initial studies with human embryonic kidney 293 cells indicate a dose dependent change in intracellular calcium content within the photothermally controlled temperature range of 37°C to 57°C. This article is protected by copyright. All rights reserved.