We are using a laser engineering approach to develop and optimize hydrous ruthenium dioxide (RuOxHy or RuO2·0.5 H2O) pseudocapacitors. We employ a novel laser forward transfer process, Matrix Assisted Pulsed Laser Evaporation Direct Write (MAPLE-DW), in combination with UV laser machining, to fabricate mesoscale pseudocapacitors and microbatteries under ambient temperature and atmospheric conditions. Thin films with the desired high surface area morphology are obtained without compromising their electrochemical performance. The highest capacitance structures are achieved by depositing mixtures of sulfuric acid with the RuO2·0.5 H2O electrode material. Our pseudocapacitors exhibit linear discharge behavior and their properties scale proportionately when assembled in parallel and series configurations.

Alumina slurries containing up to 40% by volume ceramic particles suspended in alkane waxes have been developed with viscosity sufficiently low to allow direct ink-jet printing. Components fabricated by printing have been dewaxed, sintered and shrinkage and density measured. Small differences in shrinkage have been measured parallel and perpendicular to the droplet motion but these are within experimental scatter. The manufacturing process appears to generate bands of slightly larger grain size material at the interface between deposited layers.

Microbatteries and integrated microbattery systems are likely to be the sole power source or a power-source component for the next generation of microelectronic devices. As part of the LEAPS (Laser Engineering of Advanced Power Sources) program, custom-designed microbatteries and ultracapacitors will be integrated in microelectronic circuits for optimum performance. The Naval Research Laboratory's Matrix-Assisted Pulsed-Laser Deposition Direct-Write (MAPLE DW) process is used to rapidly fabricate various primary and secondary (non-rechargeable and chargeable) electrochemical power sources. This laser forward-transfer process can be used to transfer any type of battery material and battery material mixtures, including polymers, hydrated oxides, metals, and corrosive electrolytes. Additional laser micromachining capabilities are used to tailor the battery sizes, interfaces, and configurations. Examples are given for planar RuO2 ultracapacitors and stacked alkaline batteries.

The microstructure and dielectric properties of BaTiO3 and Ba0.68Sr0.32TiO3 thick films deposited by thermal spray were investigated. The as-deposited films were predominantly crystalline with a small amount of an amorphous second phase. The as-deposited BaTiO3 films had dielectric constants as high as 240 at room temperature. Upon annealing in air at 500°C, the dielectric constant increased to 480. This increase in dielectric constant was attributed, in part, to the crystallization of the amorphous second phase. The stabilized phase depended on the spray process used. The high velocity oxy fuel (HVOF) spray process resulted in the deposition of paraelectric BaTiO3, whereas the plasma spray process resulted in the ferroelectric phase.

A three-dimensional photonic bandgap (PBG) structure was fabricated from CAD models using a method based on lost wax rapid prototyping and ceramic gelcasting. The inverse PBG mold was constructed from a low melting point thermoplastic using a high precision Sanders Rapid Toolmaker. An aqueous stable slurry (200-300 cp) containing 50-75wt% of the ceramic powders (BaSrTiO3, MgO), a 15wt% solution of monomer (Methacylamide) and crosslinker (Poly(ethylene glycol) dimethacrylate), and a free radical initiator (2,2'Azobis(2-amidino-propane) dihydrochloride) was cast into the mold. A polymerization reaction was thermally activated at 50°C to immobilize the ceramic powders. The wax mold was then removed by drying the green body in a high humidity oven at 120°C. Scanning Electron Microscopy (SEM) of the unfired part showed that atmosphere hampered the polymerization reaction at the surface of the part. The green density, sintered density, and permittivity all increased as the solids loading increased. In order to optimize the dielectric properties and minimize cracking and warping in the sintered part, the solids loading had to be greater than 80 wt%. This study investigated several steps in the lost mold / gelcasting procedure including stabilizing the ceramic suspension, the correlation between the solids loading and the green and sintered densities, binder removal, and the effect of shrinkage during sintering on the net shape.

A two-dimensional thermal model for a commercial laser additive manufacturing (LAM) process has been developed to predict the thermal history of Laser Formed Ti-6Al-4V single line (rib-on-web) builds. The thermal model has been developed to assist in the prediction and interpretation of the as-processed microstructure, which evolves as a result of the complex thermal history that develops as a result of the deposition of multiple layers of material. In the current work, the model is used to show that the presence of layer bands is a result of different regions in the build experiencing varying super b transus time, temperature, and cooling rate conditions within different regions in the build.

Fused deposition of ceramics (FDC) has been used to fabricate macroscopically graded ceramic skeletons. These Al2O3 skeletons were subjected to binder removal and sintering treatments. The sintered skeletons were infiltrated with copper alloys. Both the skeletons and composites were characterized for micro and macrostructure using scanning electron microcopy. Potential applications for the macroscopically graded ceramic/metal composites focus primarily on impact.

Applying life sciences and engineering principles to the study of cells and engineered tissue has resulted in various successes. These endeavors are poised towards development of functional neo-organs used as native tissue substitutes. Concurrent with this goal, research arenas are directed in the general areas of biocompatible polymer scaffolds, biomimmetic extracellular matrices, control of stem cell differentiation, biomolecule signaling, and directed material delivery. Optomec Inc. is developing an aerosol-based direct-write process for deposition of biological materials into three dimensional, micron-scale patterns. The process uses pneumatic atomization to produce aerosol droplets of proteinacious colloidal dispersions and whole cell suspensions. The droplets are entrained in an air stream and deposited with a proprietary deposition tool. The biological materials can be seeded into three dimensional polymer scaffolds and various substrate surfaces. Optomec's direct write process has applicability to the additive fabrication of engineered tissue. Other applications of the direct write tool include rapid prototyping of analytical biosensors, hybrid BioMEMS, and bio-chip microarray devices.

The rapid prototyping industry is growing dramatically because of its high potential to reduce product design and prototyping cycles. One of the recent technologies in this field is 3D printing using conventional ink jet technology. In order to maximize the capability of this process, it is required to understand the operating mechanism and drop formation process. The current work focuses on the mechanism of a piezoelectric cylindrical actuator and the hydrodynamic characteristics inside a print head in order to achieve more realistic boundary conditions for the numerical simulation of the drop formation process. Linearised Navier-Stokes equations for Newtonian fluid flow are solved analytically for the pump section with a constant radius and for the nozzle section with a tapering angle. Results from the developed solutions are input to Flow 3D and it is observed that analytical pressure histories show better agreement with numerical results than axial velocity histories. The presented analytic model can be used for fully further drop formation simulation as an upstream pressure boundary within an acceptable tolerance.

A laser-based tool has been developed for the fabrication of electronic circuits. The tool integrates three separate functions on a single platform. These functions are deposition, laser processing, and laser micromachining. Deposition is accomplished by dispersing a target material in a thin layer over a transparent backing layer, holding the target material in close proximity to a receiving substrate, and irradiating the target material from behind with a short pulse UV laser. The UV pulse vaporizes a small amount of the material at the material/backing interface, thereby propelling the remainder of the target material toward the receiving substrate. Patterning is achieved either by translating the receiving substrate, scanning the laser beam, or a combination of the two. After transfer, most materials require some thermal processing: either oven baking or laser sintering. Fabricated circuits have included conductors (Ag, AgPd, AgPt, Cu), resistors (cermet and polymer thick film), and dielectrics (ceramic and polymer thick film). These materials have been patterned with feature sizes as small as 10 m and linear write speeds as high as 1 meter per second. The tool includes an integrated, near IR laser which can be operated both CW and pulsed for thermal processing. Laser sintering of metals, cermet resistors, and ceramic dielectrics has been demonstrated on low temperature, polymer substrates. The localized heating achievable with the laser allows the sintering or annealing of high temperature materials without damaging the underlying substrate. The tool includes a complete, state-of-the-art laser micromachining system, capable of milling recesses, drilling vias, trimming components, and excising circuits. No masks or phototools are required. No photoresists or wet chemistries are needed. The tool does not require a clean room environment. The combined functionality and speed result in a flexible and powerful tool for the rapid prototyping of circuits, and potentially, small scale production.

We demonstrate a unique, ultrasonic direct injection method that employs nanophase materials (e.g. polymers, metal-organic and ceramic precursors). By use of in situ process control, and modification of process parameters, morphology, and structure may be varied to produce desired characteristics. By sequential application of these strategies one may fabricate MEMS, OLED's, deposit conformal coatings, create surface acoustic wave (SAW) chemical sensors, and many other thin film circuits and devices.

A computer-controlled xyz dispensing system called the Biological Architecture Tool (BAT) has been extensively tested in the creation of multilayered and three-dimensional biological objects: tissue scaffolds and plain and patterned cellular-array slides. The BAT dispensing system has proven its versatility and reliability in tissue engineering and biological experiments. The potential employments of modified versions of the xyz dispensers for in vivo minimally invasive surgery and other in vitro aspects of biological and medical research are discussed.

This paper outlines investigations into a potentially revolutionary approach to tissue engineering. Tissue is a complex three-dimensional structure that contains many different biomaterials such as cells, proteins, and extracellular matrix molecules that are ordered in a very precise way to serve specific functions. In order to replicate such complex structure, it is necessary to have a tool that could deposit all these materials in an accurate and controlled fashion. Most methods to fabricate living three-dimensional structures involve techniques to engineer biocompatible and biodegradable scaffolding, which is then seeded with living cells to form tissue. This scaffolding gives the tissue needed support, but the resulting tissue inherently has no microscopic cellular structure because cells are injected into the scaffolding where they adhere at random. We have developed a novel technique that actually engineers tissue, not scaffolding, that includes the mesoscopic cellular structure inherent in natural tissues. This approach uses a laser-based rapid prototyping system known as matrix assisted pulsed laser evaporation direct write (MAPLE DW) to construct living tissue cell-by-cell. This manuscript details our efforts to rapidly and reproducibly fabricate complex 2D and 3D tissue structures with MAPLE-DW by placing different cells and biomaterials accurately and adherently on the mesoscopic scale

Nowadays the application of micro devices in many fields like e.g. in the life sciences, chemistry and also optics strongly grows in importance. Micro structures often allow efficient processes with low resource consumption and the possibility of high integration. Typical examples are micro and nano titer plates for chemical screening or DNA chips for sequencing, micro mixers and reaction systems for synthesis on demand or micro optical elements like couplers for optical data transmission. Especially plastics are well suited for the cost effective large number fabrication, using high precision mould inserts with injection moulding or hot embossing. Since the micro devices become more and more complex (keywords: lab on a chip and micro total analysis systems, μ-TAS) the fabrication of mould inserts will be more expensive and time consuming. This is the reason why often methods of rapid prototyping are required for design qualification and functionality test purposes during the development. It will be demonstrated that Excimerlaser ablation is a well suited method for rapid prototyping of quasi-three-dimensional micro structures. Almost all polymers can be ablated by the UV laser radiation with very high accuracy, using mask projection techniques. Therefore, the choice of a suited polymer with adapted material properties like for e.g. chemical resistance, optical surface quality or bio-compatibility allows one to account for the requirements of the corresponding application. Moreover, the prototypes can easily be transformed into mould inserts for large number fabrication, using the Laser-LIGA technique. The corresponding technologies will be explained and demonstrated with the aid of several examples, especially taking into account the material aspects.

Matrix-Assisted Pulsed Laser Evaporation Direct-Write was investigated by ultra high-speed optical microscopy. A layer of viscous fluid was irradiated with 355nm, 30 ns laser pulses in a laser-forward transfer configuration. The fluid response as a function of fluence was studied, and several distinct regimes of behavior were observed: plume, jetting and sub-threshold. However, the transition between plume and jetting regimes was not readily evident in a study of transfer pixel area vs. fluence, which may be explained by material-substrate interactions.

Significant research effort is regularly applied to the goal of reducing the size of radio-frequency antennas while maintaining the entire set of positive attributes of proven but relatively large antennas. Such parameters as frequency response (multiple or single), bandwidth, and complexity of the antenna-driver balun structures require iterative optimization. The direct-write processes now available have enabled the insertion of reactive-loading elements as integral parts of the antenna structure, especially into new conformal designs. These reactive-loading elements were used in conjunction with modern design techniques to achieve antenna devices that were reduced in size to as much as half that of traditional counterparts. The performances of the miniaturized antennas constructed by direct-write methods were evaluated and compared to those of traditional antenna structures.