Flexible bottom-up assembly and integration of nanoscale materials with tunable composition and structure could make possible the development and advancement of novel fabrication strategies and unconventional integrated electronics/sensors not previously achievable with top-down approaches. We demonstrate contact-printing assembly and integration of semiconducting nanowires for three-dimensional (3D), multilayer nanowire (NW) electronics and large-scale complementary SiNW biosensor arrays, and monolithic integration of graphene-graphite for flexible bioprobes and integrated graphene electronics.

First, we achieved the assembly of highly-ordered NW arrays by contact-printing with well-controlled shear process between growth and target substrates. We show the capability of uniform and patterned automated contact-printing from single chip to a 4-inch wafer scale. We also demonstrate the power of our assembly approach with the creation of 3D NW electronics and large-scale, complementary SiNW biosensor arrays. We show, first, multilayer assembly of semiconducting NWs for 3D, multi-functional electronics, which includes (1) 10 layers of Ge/Si NW field-effect transistor (FET) arrays, (2) two-layer, multi-functional circuits assembled onto flexible plastic substrates and (3) vertically-interconnected complementary metal-oxide-semiconductor (CMOS) circuits based on heterogeneous n-InAs and p-Ge/Si NW FETs with a record high ring oscillation frequency of ca. 110 MHz. Furthermore, we present the assembly and integration of large-scale, complementary SiNW biosensor arrays capable of simultaneous, multi-channel detections with femtomolar sensitivity of prostate-specific antigen (PSA).

Second, we report monolithic integration of graphene-graphite to realize flexible, electrically-active nanoprobes, and a single-step synthesis of monolithic graphene-graphite structure to realize the integration of a whole circuit. We demonstrate that monolithically-integrated graphene-graphite nanoprobes exhibit mechanical flexibility and robustness and can be integrated onto tip of micropipette to realize a fully-functional, stand-alone nanoprobe. Furthermore, we present an unconventional synthesis approach to build monolithically-integrated electronic devices with graphene-graphite. We are able to form complex geometries of graphene transistor arrays with graphite interconnects from single-step synthesis of graphene-graphite, and the synthesized integrated devices exhibit superb mechanical flexibility and optical transparency.