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Not AvailableThis paper reports on thermally switchable tethers that control the rapid release of strained microhooks from silicon substrates. Applications include automated microassembly of electronic circuits using clips that grasp microscale (<200 micron diameter) conductive fibers, as well as assembly of microdevices onto heat-sensitive materials by grasping. We developed an integrated, photoresist-based thermal release structure that allows the first direct observations of the release process outside the etch chamber. High speed camera video (4200 frames/s) shows the cantilevers release in an order determined by thermal diffusion, with groups of ~ 1200 micron long cantilevers releasable at 100 Hz. Side-view video is analyzed to show that the height of the graspable region is approximately half the hook length. The thermally isolated release method prevents the microhooks from heating, making it potentially useful for grasping heat-sensitive polymeric and biological materials. 

This paper reports on the steps that happen after the release of strained microhooks from silicon substrates. The application is automated microassembly of electronic circuits using clips that grasp microscale (< 200 micron diameter) conductive fibers. We developed an integrated, photoresist-based thermal release structure that allows the first direct observations of the release process outside the etch chamber. High speed camera video (4200 frames/s) shows the cantilevers release in an order determined by thermal diffusion, with groups of ~1200 micron long cantilevers releasable at 100 Hz. Side-view video is analyzed to show that the height of the graspable region is approximately half the hook length. 

Fabrics and fibrous materials offer a soft, porous, and flexible substrate for microelectromechanical systems (MEMS) packaging in breathable, wearable formats that allow airflow. Device-on-fiber systems require developments in the field of E-Textiles including smart fibers, functional fiber intersections, textile circuit routing, and alignment methods that adapt to irregular materials. In this paper, we demonstrate a MEMS-on-fabric layout workflow that obtains fiber intersection locations from high-resolution fabric images. We implement an image processing algorithm to drive the MEMS layout software, creating an individualized MEMS “gripper” layout designed to grasp fibers on a specific fabric substrate during a wafer-to-fabric parallel transfer step. The efficiency of the algorithm in terms of a number of intersections identified on the complete image is analyzed. The specifications of the MEMS layout design such as the length of the MEMS gripper, spatial distribution, and orientation are derivable from the MATLAB routine implemented on the image. Furthermore, the alignment procedure, tolerance, and hardware setup for the alignment method of the framed sample fabric to the wafer processed using the custom gripper layout are discussed along with the challenges of the release of MEMS devices from the Si substrate to the fabric substrate.