The primary goal of an ongoing research effort at LSU is to develop the three-step LIGA process to inexpensively manufacture high aspect ratio microstructures (HARMs). The ®rst two steps of the process (lithography and electroplating) produce a metallic mold insert that can be used as a template for molding microstructures. The ®nal step of LIGA is molding. This paper focuses on injection molding of thermoplastics to produce surfaces covered with HARMs. The resulting microstructures are hundreds of micrometers in height, tens of micrometers in width, and separated by gaps on the order of tens of micrometers. Injection molding experiments using high density polyethylene were performed using a commercially available injection molding machine. Experimental variables included injection speed, the tool temperature, and air pressure in the mold cavity. Elevating the tool temperature above the melting point ensured that the polymer completely ®lled the mold, producing microstructures with the desired geometry. As the temperature of the mold was reduced, higher injection speeds did not necessarily ensure ®lling of the mold cavity. The cycle time is shorter than the values previously reported in the literature [Madou (1996)].

Polyester (PET) swatches are treated with an electrical discharge plasma of a reactive atmosphere (tetrachlorosilane) to graft chlorosilane groups, subsequently hydrolyzed to very hydrophilic hydroxysilane groups. The Kawabata evaluation system for fabrics (KES-FB), high resolution microscopy, and surface tension measurements are used to investigate the physical properties of the fabrics before and after plasma exposure. The results show that the surface parameters are considerably modified by the treatment.

The tSET research group at LSU is developing the three-step LIGA process to inexpensively manufacture high aspect ratio microstructures (HARMs). The first two steps of the process (lithography and electroplating) produce a metallic mold insert that is used as a template for molding microstructures. This paper focuses on injection molding of thermoplastics to produce surfaces covered with HARMs hundreds of micrometers in height, tens of micrometers in width, and separated by gaps on the order of tens of micrometers. Injecting plastic into the narrow, high aspect ratio gaps existing in the HARMs mold inserts (micromolding) offers a set of challenges different from classical injection molding of larger scale parts. This paper provides results of a series of injection molding experiments using a commercially available injection molding machine. Replication of the HARMs was achieved by increasing the injection speed, elevating the tool temnerature, and venting the mold cavity.Electron microscopy was used to investigate and assess the molding results.

A novel and simple microfluidic device was developed for sorting 20 microm thick glass microbarcodes for imaging or scanning at the completion of a bead-based assay. Specifically, the microbarcodes are dried and kept from stacking on top of one another such that a monolayer of microbarcodes is created and the microbarcodes lay flat on a surface. The microbarcode sorting device consists of a reservoir, a sorting region, and a network of microchannels. With minimal microbarcodes loss, a monolayer of microbarcodes is created and trapped inside the sorting region for conveniently imaging or scanning. The device can also be used for any geometrical shaped beads with a range of thicknesses and can be adapted to a 96-well plate format for high throughput analysis.

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