Saul Griffith

Programmable Assembly With Universally Foldable Strings (Moteins)

Understanding how linear strings fold into 2-D and 3-D shapes has been a long sought goal in many fields of both academia and industry. This paper presents a technique to design self-assembling and self-reconfigurable systems that are composed of strings of very simple robotic modules. We show that physical strings that are composed of a small set of discrete polygonal or polyhedral modules can be used to programmatically generate any continuous area or volumetric shape. These modules can have one or two degrees of freedom (DOFs) and simple actuators with only two or three states. We describe a subdivision algorithm to produce universal polygonal and polyhedral string folding schemas, and we prove the existence of a continuous motion to reach any such folding. This technique is validated with dynamics simulations as well as experiments with chains of modules that pack on a regular cubic lattice. We call robotic programmable universally foldable strings “moteins” as motorized proteins.

Nanostructure fabrication by direct electron-beam writing of nanoparticles

Direct additive-layer fabrication of nanostructures is a widely sought goal, which is not possible using traditional layered resist optical and electron-beam lithographic techniques. However, recently, it has been shown that certain metallic and semiconducting nanoparticles capped with protective organic groups are promising “inklike” resist materials for patterning a variety of electronic and mechanical structures [C. A. Bulthaup et al., Appl. Phys. Lett. 79, 1525 (2001)]. Several groups have successfully patterned single-layer gold nanoparticle films by means of direct electron-beam writing [X. M. Lin, R. Parthasarathy, and H. M. Jaeger, Appl. Phys. Lett. 78, 1915 (2001); T. R. Bedson, R. E. Palmer, T. E. Jenkins, D. J. Hayton, and J. P. Wilcoxon, Appl. Phys. Lett. 78, 1921 (2001); L. Clarke et al., Appl. Phys. Lett. 71, 617 (1997)]. In this work, we apply these materials in a new lithographic mode, using an electron beam to cause direct sintering of these 2–10 nm nanoparticles, building structures of m...

Conductive nanostructure fabrication by focused ion beam direct-writing of silver nanoparticles

A focused ion beam has been used to directly pattern thin films of organometallic silver nanoparticles down to a resolution of 100nm. The unexposed regions were washed in hexane leaving the desired pattern, and subsequent annealing formed conductive, metallic features. Multiple-layer structures were also fabricated by spin-coating and exposing additional films of silver nanoparticles on top of already patterned structures. The sensitivity of the nanoparticles to 30keVGa+ ions was measured to be approximately 5μC∕cm2. Using this technique test structures were fabricated in two and three dimensions with resistivities as low as 288μΩcm and 13μΩcm for single- and multiple-layer structures, respectively, as compared to a value of 1.589μΩcm for bulk silver. To our knowledge, this is the highest demonstrated throughput for any electron or ion beam direct-write process utilizing metal-organic precursors.