Self-assembly, transfer and integration

Wolf et al. introduced the self-assembly, transfer, and integration (S ATI) of nanoparticles with high placement accuracy.86 87 Silica and polymer nanoparticles were positioned on a PDMS stamp through convective assembly (Fig. 13.14). By controlling the printing temperature or by using a thin polymer layer as an adhesion layer, nanoparticles of different shapes and sizes were printed onto the target substrate. 

Kraus, T., Malaquin, L., Delamarche, E., Schmid, H., Spencer, N.D., and Wolf, A. Closing the gap between self-assembly and microsystems using self-assembly, transfer and integration (SATl) of particles, Adv. Mater., 17, 2438, 2005. 

Our further collaboration with IBM involved an extension of printing methods to small objects rather than molecules. This is of practical interest for device manufacture, since it could potentially allow the integration of high-resolution self-assembly procedures, physically separated from the main fabrication line, followed by a printing step to place the objects onto the device (an approach called Self-Assembly, Transfer, and Integration (SATI)) (4.14). This has been extended to the nanometer scale (4.15), and by means of specially structured surfaces, can also be used to place objects of different sizes in distinct patterns onto a surface (4.16). 

Closing the Gap Between Self-Assembly and Microsystems Using Self-Assembly, Transfer, and Integration (SATI) of Particles T. Kraus, L. Malaquin, E. Delamarche, H. Schmid, N. D. Spencer, H. Wolf Adv. Materials 2005 17 pp 2438-2442... 

A similar supramolecular approach, in which both n-n stacking stacking of pyrene on the SWNT surface and alkyl ammonium-crown ether interactions were used in the self-assembly process of a fullerene derivative with SWNTs, was recently reported (Scheme 9.22).72 The nanohybrid integrity was probed with various spectroscopic techniques, , and electrochemical measurements. Nanosecond transient absorption studies confirmed electron transfer as the quenching mechanism of the singlet excited state of C60 in the nanohybrid resulting in the formation of SWNT"1"/ Pyr-NH3 + /crown- charge-separated state. 

Layer-by-layer (LbL) assembly is a unique technique for the fabrication of composite films with precise thickness control at the nanometer scale [111, 112], The method is based on the alternate adsorption of oppositely charged species from their solutions. The attractive feature of this approach is its ability to assemble complex structures from modular components, and integrate them into self-assembling constructions for a wide range of applications. The LbL method has been successfully exploited in the construction of dendrimer biosensors [113,114], The LbL films provide a favorable environment for the intimate contact between the dendrimer and biomolecule (enzymes or proteins), promoting a direct electron transfer between them and the underlying electrodes. 

Figure 1. Single-step self-assembly versus the multistep SATI process. Conventional self assembly processes order particles and establish a strong particle-substrate connection In a single step (assemble and Integrate). In the SATI process, self-assembly is only used to assemble particles in a predefined order at a low level of adhesion. The particles are then transferred by a carrier at moderate adhesion levels that allow their handling without perturbing their order, and finally integrated on the target substrate at high adhesion levels so that further processing is possible.

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