Nanowire active-matrix circuitry for low-voltage macroscale artificial skin

Large-scale integration of high-performance electronic components on mechanically flexible substrates may enable new applications in electronics, sensing and energy(1-8). Over the past several years, tremendous progress in the printing and transfer of single-crystalline, inorganic micro-and nanostructures on plastic substrates has been achieved through various process schemes(5-10). For instance, contact printing of parallel arrays of semiconductor nanowires (NWs) has been explored as a versatile route to enable fabrication of high-performance, bendable transistors and sensors(11-14). However, truly macroscale integration of ordered NW circuitry has not yet been demonstrated, with the largest-scale active systems being of the order of 1 cm(2) (refs 11,15). This limitation is in part due to assembly-and processing-related obstacles, although larger-scale integration has been demonstrated for randomly oriented NWs (ref. 16). Driven by this challenge, here we demonstrate macroscale (7 x 7 cm(2)) integration of parallel NW arrays as the active-matrix backplane of a flexible pressure-sensor array (18 x 19 pixels). The integrated sensor array effectively functions as an artificial electronic skin(2,17,18), capable of monitoring applied pressure profiles with high spatial resolution. The active-matrix circuitry operates at a low operating voltage of less than 5V and exhibits superb mechanical robustness and reliability, without performance degradation on bending to small radii of curvature (2.5 mm) for over 2,000 bending cycles. This work presents the largest integration of ordered NW-array active components, and demonstrates a model platform for future integration of nanomaterials for practical applications.