The Development of a Method of Producing Etch Resistant Wax Patterns on Solar Cells

The first quarter of a one-year program to investigate the production of patterned etch resistant wax coatings on solar cell substrates by printing is reported. Master molds for printing plates were produced for the plates. The resist wax is being studied to determine its relevant physical properties. A printing device is currently in design, and material costs are being compiled as first step in a cost analysis task. All phases of the project are proceeding according to schedule. No specific phases are yet completed

Fabricating Microfluidic Valve Master Molds in SU‐8 Photoresist

Multilayer soft lithography has become a powerful tool in analytical chemistry, biochemistry, material and life sciences, and medical research. Complex fluidic micro-circuits require reliable components that integrate easily into microchips. We introduce two novel approaches to master mold fabrication for constructing in-line micro-valves using SU-8. Our fabrication techniques enable robust and versatile integration of many lab-on-a-chip functions including filters, mixers, pumps, stream focusing and cell-culture chambers, with in-line valves. SU-8 created more robust valve master molds than the conventional positive photoresists used in multilayer soft lithography, but maintained the advantages of biocompatibility and rapid prototyping. As an example, we used valve master molds made of SU-8 to fabricate PDMS chips capable of precisely controlling beads or cells in solution

Blazed and Slanted Grating Mastering using Crystallography-based Silicon Etching

This disclosure describes crystallographic etching techniques to manufacture blazed or slanted silicon gratings such that their characteristic angles are defined by the facet angles of the silicon crystal substrate. The techniques enable the manufacture of precisely formed and uniform gratings with smooth surfaces over large areas. The grating pattern is achieved by using anisotropic, potassium hydroxide based, crystallographic etching of a silicon wafer along selected crystal planes. The grating structures manufactured by the described techniques can be used as master molds for replicated fabrication of nano-imprint optical devices such as waveguides

Aligning carbon nanofibers in PCL microfibers using microfluidic method: An approach to efficiently improve electrical conductivity and mechanical strength

In this thesis work, electrically conductive CNF/PCL composite fibers were fabricated using the microfluidic method. The fibers were made with different content levels of CNFs and flow rate ratios between the core and sheath fluids. The electrical conductivity and tensile properties of these fibers were then investigated. A cross-flow geometry microfluidic channel with four chevron-shaped grooves as shaping elements was designed for microfluidic fiber fabrication. A CNC micro-milling machine was used to create the PMMA master molds, the surfaces of which were further smoothened by chloroform vapor. PDMS microchannel was prepared by molding replication based on the micro-machined PMMA master molds. Using the as-fabricated PDMS microchannel, electrically conductive CNF/PCL composite fibers were successfully fabricated using the microfluidic method. It was found that at a CNF concentration of 3 wt.%, the electrical conductivity of the composite fiber increased to 1.11 S/m, which was around 1015 times of the electrical conductivity of the pure PCL. The yield strength, Young’s Modulus and ultimate strength of the 3 wt.% CNF/PCL composite fiber increased relative to the pure PCL fiber by a factor of 1.72, 2.88, and 1.23, respectively. Further increasing the content of CNF, the electrical conductivity increased slightly, while the tensile strength dropped sharply due to the agglomeration of CNF. Additionally, the results showed that the microfluidic could be considered as an effective method to align CNFs along the fiber in the longitudinal direction. The alignment of the CNFs showed a positive effect on the electrical conductivity and tensile strength

Injectable and Spatially Patterned Microporous Annealed Particle (MAP) Hydrogels for Tissue Repair Applications.

Spatially patterned hydrogels are becoming increasingly popular in the field of regenerative medicine and tissue repair because of their ability to guide cell infiltration and migration. However, postfabrication technologies are usually required to spatially pattern a hydrogel, making these hydrogels difficult to translate into the clinic. Here, an injectable spatially patterned hydrogel is reported using hyaluronic acid (HA)-based particle hydrogels. These particle hydrogels are sequentially loaded into a syringe to form a pattern and, once injected, they maintain the pattern. The applicability of this hydrogel in a wound healing skin model, a subcutaneous implant model, as well as a stroke brain model is examined and distinct patterning in all models tested is shown. This injectable and spatially patterned hydrogel can be used to create physical or biochemical gradients. Further, this design can better match the scaffold properties within the physical location of the tissue (e.g., wound border vs wound center). This allows for better design features within the material that promote repair and regeneration

Development of optical sensing system for detection of Fe ions using conductive polymer actuator based microfluidic pump

In this paper, we present a novel microfluidic optical sensing system by combining a low-power conductive polymer -based microfluidic pump and a microfluidic chip integrated with an optical sensor. A self priming microfluidic pump is developed using a polypyrrole. A microfluidic chip- optical detector module that contained an optical cuvette with LED and photo-diode optical sensing module was fabricated. Integration of the micro pump and the microfluidic chips complete the sensing system. The pump performance and its application in chemical analysis have been demonstrated in the detection of Fe ions

Flexible Mold for Microstructures Replication

Space debris has been a growing concern in space exploration sector. To combat this issue, biomimicry is utilized to create a gecko’s feet microstructure that will be attached to a gripper or robotic arm. This will enable capture of debris through the use of dry adhesive microstructure. However, the production of such microstructures is expensive which hinders their implementation. The objective of this research is to develop an advanced fabrication process to mass produce gecko’s feet microstructure with soft polymer mold. The possibility of using different coating methods with coating materials will be justified. The process of fabricating mold and replicating mold will be optimized. The method of mass producing microstructures will be verified and the limitation of the method will also be studied

A microfluidic 2×2 optical switch

A 2×2 microfluidic-based optical switch is proposed and demonstrated. The switch is made of an optically clear silicon elastomer, Polydimethylsiloxane (PDMS), using soft lithography. It has insertion loss smaller than 1 dB and extinction ratio on the order of 20 dB. The device is switching between transmission (bypass) and reflection (exchange) modes within less than 20 m