We demonstrate the use of self-assembly for the integration of freestanding micrometer-scale components, including single-crystal, silicon field-effect transistors (FETs) and diffusion resistors, onto flexible plastic substrates. Preferential self-assembly of multiple microcomponent types onto a common platform is achieved through complementary shape recognition and aided by capillary, fluidic, and gravitational forces. We outline a microfabrication process that yields single-crystal, silicon FETs in a freestanding, powder-like collection for use with self-assembly. Demonstrations of self-assembled FETs on plastic include logic inverters and measured electron mobility of 592 cm 2 ͞V-s. Finally, we extend the self-assembly process to substrates each containing 10,000 binding sites and realize 97% self-assembly yield within 25 min for 100-m-sized elements. High-yield self-assembly of micrometer-scale functional devices as outlined here provides a powerful approach for production of macroelectronic systems.acroelectronics is an emerging area of interest in the semiconductor industry. Unlike the traditional pursuit in microelectronics to build smaller devices and achieve higher degrees of integration over small areas, macroelectronics aims to construct distributed active systems that cover large areas. Often, these systems are constructed on flexible substrates with multiple types of components and allow for distributed sensing and control. A number of applications are already under consideration for macroelectronics, including smart artificial skins (1), large-area phased-array radars (2), solar sails (3), flexible displays (4, 5), electronic paper (4), and distributed x-ray imagers (6). A candidate macrofabrication technology must be able integrate a large number of various functional components over areas exceeding the size of a typical semiconductor wafer in a cost-effective and time-efficient fashion.The substrate of choice for many macroelectronic applications is plastic. Flexible plastic substrates are thermally and chemically incompatible with conventional semiconductor fabrication processes. To incorporate electronic devices, a number of venues have been explored for low-temperature integration of semiconductors on plastics. The integration of semiconductor is followed by steps to build and interconnect functional devices. These material integration methods have demonstrated functional devices on plastic built from amorphous silicon (7), low-temperature polysilicon (8), and organic semiconductors (9, 10). Although in some applications low-performance devices are acceptable, in many applications, such as phased-array radar antennas or radio frequency tags, the integrated devices are required to perform at high frequencies with low power consumption. Devices built with the material integration methods outlined above suffer from low charge carrier mobility. Typical amorphous silicon transistors have electron mobility of 1 cm 2 ͞ V-s (11), low-temperature polysilicon transistors on plastic have electron mobilit...