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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. 

Microelectromechanical systems (MEMS) assembly into packages that interface with the environment is critical in electronic sensor applications ranging from soft biomedical systems to telecommunications. This article presents a novel process using heat-depolymerizable polyethylene carbonate (QPAC-25) as a sacrificial tether, and demonstrates it for assembling waferbound MEMS onto wires. The assembly mechanism is thermal removal of the tether, allowing a strained layer to pop up from the substrate and make electrical and mechanical contact with the wire. We detail the QPAC-25 fabrication procedures, characterize the relationship between QPAC-25 thickness and spin speed and determine a route to pattern QPAC-25 without a metal hard mask or photosensitizers 

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. 

Packaging electronic devices within electronic textiles and fibrous substrates requires an understanding of how fibers interact with circuit components in different operating conditions. In this paper, we use microeletromechanical (MEMS) devices to put devices in electrical contact with fine wires. We characterize the electronic properties of MEMS-to-wire contacts and discuss general guidelines for optimizing the design of these grippers and potential MEMS-based circuits. We then demonstrate how these grippers can act as non-rigid circuit components that effectively transfer power to devices such as LEDs. Analysis shows that our grippers are suitable conductors (under 150 Ohms) under standard operating temperatures (25-100 deg. C) with potential for use as sensors for current overflow or temperature. Methods such as parylene deposition and silver epoxy to stabilize MEMS performance are briefly discussed and explored.