RESUMEN
A method for the cascaded capillary assembly of different particle populations in a single assembly cycle is presented. The method addresses the increasing need for fast and simple fabrication of multicomponent arrays from colloidal micro- and nanoscale building blocks for constructing nanoelectronic, optical, and sensing devices. It is based on the use of a microfluidic device from which two independent capillary bridges extend. The menisci of the capillary bridges are pulled over a template with trapping sites that receive the colloidal particles. We describe the parameters for simultaneous, high-yield assembly from both menisci and demonstrate the applicability of the process by means of the size-selective assembly of particles of different diameters and also by the fabrication of two-component particle clusters with defined shape and composition. This approach allows the fabrication of multifunctional particle clusters having different functionalities at predetermined positions.
RESUMEN
In this paper, a fast and inexpensive wafer-scale process for the fabrication of arrays of nanoscale holes in thin gold films for plasmonics is shown. The process combines nanosphere lithography using spin-coated polystyrene beads with a sputter-etching process. This allows the batch fabrication of several 1000 microm(2) large hole arrays in 200 nm thick gold films without the use of an adhesion layer for the gold film. The hole size and lattice period can be tuned independently with this method. This allows tuning of the optical properties of the hole arrays for the desired application. An example application, refractive index sensing, is demonstrated.
RESUMEN
The use of force spectroscopy to study the adhesion of living fibroblasts to their culture substrate was investigated. Both primary fibroblasts (PEMF) and a continuous cell line (3T3) were studied on quartz surfaces. Using a fibronectin-coated AFM cantilever, it was possible to detach a large proportion of the 3T3 cells from the quartz surfaces. Their adhesion to the quartz surface and the effects of topography on this adhesion could be quantified. Three parameters characteristic of the adhesion were measured: the maximum force of detachment, the work of adhesion, and the distance of detachment. Few PEMF cells were detached under the same experimental conditions. The potential and limitations of this method in measuring cell/surface interactions for adherent cells are discussed.