Active polymeric composite membranes for localized actuation and sensing in microtransfer printing

Soft locally active structures are becoming increasingly important in a number of applications, from microfluidic systems to soft robotics. In this paper, we develop an active polymeric composite membrane for use as an active stamp in the microtransfer printing process. The membrane is a composite of multiple layers: 1) a soft polydimethylsiloxane layer for transfer printing; 2) a lead zirconate titanate (PbZr_0.52Ti_0.48O₃) layer for actuation; 3) metal layers for strain sensing and interconnects; and 4) patterned photopolymer (SU-8) layers for selectively tuning the compliance in the membrane and for handling. A novel and scalable fabrication approach that uses photolithography and microtransfer printing is developed for heterogeneously integrating the different materials into a functional structure. Approaches to designing and characterizing these active membranes are also discussed. Finally, the use of such membranes as stamps in the microtransfer printing process is demonstrated. By distributing actuation closer to critical regions of the tool, adaptability to local conditions for increased robustness and greater process flexibility is achieved.