Magnetically Actuated Single-Cell Microgrippers

Microtools that can manipulate single cells can be used to probe tissue heterogeneity and investigate cell mechanobiology questions of broad relevance to tissue engineering and the understanding and development of several diseases. Existing tools are either large or manipulated by hand, limiting throughput and scalability. Here, we report the development of single-cell scale microgrippers with precise and reversible magnetic actuation for cellular manipulation and mechanoresponse study. The microgrippers consist of flexible nanoscale thin-film hinges and rigid arms integrated with magnetic materials. With the appropriate use of sacrificial films, the arms of the grippers can be released from the substrate. Pre-stressed hinges power the microgripper and allow it to self-fold into a half-open pyramidal 3D cavity, small enough to encapsulate a single cell. Using an external magnetic field, we show that we can control the arms to exert force precisely on the encapsulated cell. The motion and force output of microgripper arms are predictable by a theoretical model. We discuss studies of microgrippers capturing and exerting forces on micro-objects such as cells and microbeads and show that the arms of the microgripper can be reversibly actuated over hundreds of cycles. Moreover, the lithographic fabrication and small dimensions of microgrippers allow us to fabricate them <i>en masse</i> using wafer-scale scalable processes, improving experimental throughput and cost-effectiveness. We envision that these new microtools can be readily integrated with lab-on-a-chip devices and advance single-cell studies.