We demonstrate drop-on-demand inkjet printing technique to be a high throughput method for the patterned deposition of UV-curable epoxy materials. Different multi-nozzle printheads have been used to produce epoxy droplets with controlled volume in the range from 15 to 180 pl, and to apply the droplets with high placement accuracy. For a large dot grid pattern, which was printed by addressing 126 individual ink channels, standard deviations of σx = 2.3 μm and σy = 2.6 μm have been achieved for the error in dot placement. The deposited epoxy dots were found to form planar convex lenses with a focal length of 142 μm. In addition, we have successfully printed magnetic nanoparticles in a carrier fluid with the drop-on-demand printheads, as a step towards the production of composites.

Collagen scaffolds have been produced that incorporate predefined internal channels. The scaffolds were obtained with the aid of sacrificial moulds that have been manufactured using a rapid prototyping technique. A computer aided design file of the mould was created and then realised using an ink-jet printer. A dispersion of collagen was then cast into the mould and frozen. Ethanol was used to dissolve the mould leaving the collagen, which was then freeze dried to produce the final product. The scaffold was then analysed using X-ray microtomography (XMT) to determine whether the desired internal structure was obtained. It was found necessary to add saturated potassium iodide (KI) solution to the scaffold in order to analyse it satisfactorily by XMT. The resultant images indicate that the desired internal structure was obtained.

We are developing a laser engineering approach to fabricate and optimize various types of alkaline microbatteries. Microbattery cells are produced using a laser forward transfer process that is compatible with the materials required to make the anode, cathode, separator and current collectors. The use of an ultraviolet transfer laser (wavelength = 355 nm, 30 ns FWHM) enables other operations such as surface processing, trimming and micromachining of the transferred materials and substrate and is performed in situ. Such multi-capability for adding, removing and processing material is unique to this direct-write technique and provides the ability to laser pattern complicated structures needed for fabricating complete microbattery assemblies. In this paper, we demonstrate the production of planar zinc-silver oxide alkaline cell by laser direct-write under ambient conditions. The microbattery cells exhibit 1.5–1.6 V open circuit potentials, as expected for the battery chemistry and show flat discharge behavior under constant current loads.

Dip Pen Nanolithography (DPN) is a lithographic technique that allows direct deposition of chemicals, metals, biological macromolecules, and other molecular “inks” with nanometer dimensions and precision. This paper addresses recent developments in the design and demonstration of high-density multiprobe DPN arrays. High-density arrays increase the process throughput over individual atomic force microscope (AFM) probes and are easier to use than arrays of undiced commercial probes. We have demonstrated passive arrays made of silicon (8 probes, 310 μm tip-to-tip spacing) and silicon nitride (32 probes, 100 μm tip-to-tip spacing). We have also demonstrated silicon nitride “active” arrays (10 probes, 100 μm tip-to-tip spacing) that have embedded thermal actuators for individual probe control. An optimization model for these devices, based on a generalized multilayer thermal actuator, is also described.

Over the last two decades, there has been a trend towards the development of smaller and more autonomous electronic devices, yet the question of how to power these microdevices with correspondingly small power sources remains. To address this problem, we employ a laser forward-transfer process in combination with ultraviolet laser micromachining, to fabricate mesoscale electrochemical power sources, such as microbatteries and micro-ultracapacitors. This direct-write laser-engineering approach enables the deposition of battery materials (hydrous ruthenium oxide, manganese oxide, lithium cobalt oxide, etc.) under ambient temperature and atmospheric conditions, resulting in films with the desired morphological and electrochemical properties. Planar and stacked cell configurations are produced and tested for their energy storage and power delivery capabilities and exhibit favorable performance in comparison to current battery technology.

Advanced and novel fabrication methods are needed to build complex three-dimensional scaffolds that incorporate multiple functionally graded biomaterials with a porous internal architecture that will enable the simultaneous growth of multiple tissues, tissue interfaces and blood vessels. The aim of this research is to develop, demonstrate and characterize techniques for fabricating such scaffolds by combining solid freeform fabrication and computational design methods. When fully developed, such techniques are expected to enable the fabrication of tissue engineering scaffolds endowed with functionally graded material composition and porosity exhibiting sharp or smooth gradients. As a first step towards realizing this goal, scaffolds with periodic cellular and biomimetic architectures were designed and fabricated using selective laser sintering in Nylon-6, a biocompatible polymer. Results of bio-compatibility and in vivo implantation studies conducted on these scaffolds are reported.

The dielectric properties of high k dielectric thick films prepared by thermal spray were investigated. BaTiO3 and Ba0.68Sr0.32TiO3 thick films were deposited using plasma spray on Ag-Pd screen-printed alumina substrates. The sprayed films were predominantly polycrystalline but contained an amorphous second phase. The dielectric constants of the films decreased with decreasing film thickness in 10 ∼ 60 μm range. This was attributed to the presence of an interfacial layer between the film and the substrate as determined by capacitance measurements. The capacitance density of the interfacial layer was determined to be ∼ 2.7 nF/cm2. The capacitance density of the interfacial layer increased to 12 nF/cm2 after post heat treatment at 500 °C for 20 hours.

The traditional Slurry-based Three-dimensional Printing (S-3DP™) process has been used to fabricate complex structure materials by printing organic binders in selected positions on each printing layer. This process is modified to fabricate functional graded materials, such as gradient index (GRIN) lenses, by depositing different concentrations of dopant at different positions. The modified S-3DP™ process offers advantages over conventional GRIN lens processes, including reduced processing time, improved compositional flexibility, and increased index profile dimensionality. Two different approximately parabolic dopant concentration profiles, which have maximum alumina concentrations of 1.63 mol% and 2.50 mol%, are printed into silica powder beds using S-3DP™. The samples with maximum alumina concentration of 1.63 mol% have been sintered into optical transparency at 1650 0C for 30 minutes in a vacuum furnace (5×10-6 torr) while an additional dehydration process before sintering was required for the samples with maximum alumina concentration of 2.50 mol%. The magnifying effects of GRIN lenses with profiles of 1.63 mol% and 2.50 mol% alumina were observed, yielding effective focal lengths of 10 cm and 6.1 cm, respectively. Light diffraction, which results from the locally inhomogeneous dopant distribution and reduces the optical quality of GRIN lenses, was also observed.

Cold Gas Dynamic Manufacturing (CGDM) is a high-rate, direct deposition process capable of combining many dissimilar materials in the production of a single component. The process is based on Cold Gas Dynamic Spraying (CGDS) – a surface coating technology in which small, un-heated particles are accelerated to high velocities (typically above 500 m/s) in a supersonic gas jet and directed towards a substrate material. The process does not use a heat source (as with similar plasma and HVOF spray technologies), but rather employs the high kinetic energy of the particles to effect bonding through plastic deformation upon impact with the substrate or previously deposited layer. As a consequence it lends itself to the processing of temperature sensitive material systems such as oxidising, phase-sensitive or nano-structured materials. To achieve metallic bonding incident particles require velocities greater than a certain material-specific threshold value, such that thin surface films are ruptured, generating a direct interface. This bonding mechanism has been compared to explosive welding.

This paper discusses the further development of the CGDS technique from surface coating technology into the basis for a novel Additive Fabrication process. The description of the apparatus is presented in addition to the basic processing conditions for the deposition of aluminium material. Particular attention is paid to the morphology of the deposited material, the microstructure and the interfacial boundary between splats.

Programmable methods for transferring materials to surfaces in patterns can produce structures with micrometer and nanometer scale features. All such technologies involve combinations of information, materials and energy. The materials in additive technologies can originate in the vapor phase, as liquids or suspensions, or as solids. The energy can come from laser, electron or ion beams, or the pressures used in writing, dispensing, jetting or flow methods. Many of the programmable techniques do not require high temperatures, so they can be used to make fine-scale structures of organic and bio-materials, and even live biologicals. Quantitative comparisons of both additive and subtractive programmable methods show that only a few, based on electron or ion beams, or on proximal probes, are capable of making nanometer-scale structures. Assembly methods, notably self- and directed-assembly, should prove to be central to the realization of manufacturable nanotechnology. Programmable deposition technologies may be used to supply materials for, and otherwise control self-assembly processes. The four sets of technologies, namely masked lithography, direct-write techniques, self-assembly and directed-assembly, provide a versatile and powerful toolbox for making micro-and nano-meter scale devices and systems.

Tissue engineering tries to grow replacement tissues to repair damaged bones. In this paper, the fabrication technology of Multi-nozzle Deposition Manufacturing (MDM) was adopted to fabricate scaffolds of a tissue engineered bone at low temperature. The composite of poly(L-lactic acid) and tri-calcium phosphate (TCP) was chosen to form bone tissue engineering scaffolds. The new computer aided manufacturing process can make porous PLLA/TCP scaffolds. A new surface processing technology of apatite coating on bone tissue engineered scaffolds was also adopted. This digital forming technology was based on rapid prototyping (RP), in which a digital droplets assembly technology was introduced. The MDM technology of 4 nozzles was developed based on the layer-by-layer manufacturing principle of Solid Freeform Fabrication (SFF) in our laboratory. The bone scaffolds made by the multi-nozzle deposition process in the MDM system have good biocompatibility and bone conductive properties as a molecular scaffold for bone morphogenic protein (BMP) in the implantation experiment of repairing segment defects in rabbits' and dogs' radiuses.

Laser polishing of indirect-SLS parts made from 420 stainless powder infiltrated with bronze has been achieved using CO2 and Nd:YAG lasers. Two mechanisms have been previously proposed for the reduction in surface roughness, namely: shallow surface melting (SMM) and surface over-melt (SOM). In SMM reflow of the molten surface minimizes the peak-valley height driven by capillary pressure and liquid curvature. On the other hand, during SOM the melting depth is such that the entire surface becomes liquid and formation of surface periodical structures dominates driven by a surface tension gradient. This surface morphology was identified by means of optical and scanning electron microscopy (SEM). The onset of this regime is dictated by the energy density (i.e., ratio of laser power to scan speed and beam diameter) as well as the initial roughness Ra value prior to laser surface polishing. In contrast with SMM, onset of the latter mechanism increases the roughness Ra with speed reduction. A thermo-physical model is presented, signaling good agreement with roughness Ra and characteristic surface wavelength results obtained for varying laser beam scan speeds. Understanding the surface over-melt mechanism is critical for determining the optimum polishing conditions that minimize roughness.

The world's first microstereolithography named “IH process” was developed by Ikuta et al. in 1992. Several types of micro stereo lithography including Hybrid-IH process, Super-IH process and Two-photon IH process, have been also developed. Three-dimensional (3D) resolution has reached to 140 nm in the two-photon IH process. The super-IH process and the two-photon process enable direct writing of movable micromechanisms without assembling process or sacrificial layer technique. The hybrid-IH process provides various types of composite devices with other functional elements such as actuators and sensors. These IH processes can be widely used for making polymeric microdevices. We have applied these techniques to create new micro chemical device named “Biochemical IC Chip” proposed by Ikuta et al. in 1994. IH process enables to make the biochemical IC chip including real 3D micro fluidic channels. Various kinds of Biochemical IC chip such as micro pumps, switching valves, reactors, concentrators, have already been fabricated. In chip cell-free protein synthesis has been demonstrated by using biochemical IC chips. The biochemical IC chips will open new bioscience and medicine based on innovative technology. In this paper, we introduce several types of IH process and its application to biochemical IC chips.

Two laser-based direct-write techniques to guide particles from a mist source to a target substrate by laser beams were recently developed at Michigan Tech. The laser-guided direct-write (LGDW) technique uses a hollow optical fiber, while the laser-guided microsensor patterning (LGMP) technique uses a micrometer-sized aperture. The techniques are suggested to be utilized for patterning microstructures made of nanoparticles that are either crystallized from liquid precursors or directly deposited from nanoparticle-in-liquid suspensions. The computational results based on the paraxial Fraunhofer approximation of a Gaussian beam diffracted by a circular aperture and experimental measurements of corresponding deposition rate under different conditions suggest several factors for setup optimization of LGMP. The results indicate that among the most important factors are the aperture size relative to the laser beam-waist size and the divergence of the beam near the aperture. Examples of gold-thiolate, protein-coated polystyrene, and carbon-polymer composites deposition are presented.

Direct-write techniques allow processing in the nanometer range and have become powerful methods for rapid prototyping of microelectronic circuits and micro-electro-mechanical systems (MEMS). Chemical reactions are initiated by a focused beam leading to deposition of solid material on literally any surface. We have used this method to deposit metals such as tungsten and dielectrics such as silicon oxide using a focused ion beam (FIB) with 10 to 50 kV acceleration voltage. Controlled guidance of the beam allows deposition of both metallic and dielectric material with features in the 100 nm range. The deposition of separate structures of metallic and dielectric material deposited next to each other is shown on samples of different roughness. 3-dimensional exemplary prototypes in the sub-μm range and multilayer structures demonstrate the versatility of this method for prototyping and mix-and-match approaches with commercial semiconductor devices. A characterization of the deposited material was performed to clarify chemical composition and surface morphology of deposited structures. The deposition parameters were found to influence the chemical composition and electronic properties of the material. Direct-write deposition of dielectrics and metals by FIB allows fabrication of 3-dimensional prototypes with custom-tailored material properties.

For laser nanofabrication using two-photon photopolymerization, a deep understanding of the nature of focal spots that are related to two-photon excitation is essential for achieving a high spatial resolution in three dimensions. Here we report the use of a technology we call ascending scan for characterizing the three-dimensional size and shape of single polymerization elements (voxels), and introduce several features of voxels that have not been fully noticed before. These findings are important for tailoring nanofeatures according to design.

Layered Manufacturing (LM) refers to computer-aided manufacturing processes in which parts are made in sequential layers relatively quickly. Parts that are produced by LM can be formed from a wide range of materials such as photosensitive polymers, metals and ceramics in sizes from a centimeter to a few meters with sub-millimeter feature resolutions. LM has found use in diverse areas including biomedical engineering, pharmaceuticals, aerospace, defense, electronics and design engineering. The promise of LM is the capability to make customized complex-shaped functional parts without specialized tooling and without assembly. LM is still a few years away from fully realizing its promise but its potential for manufacturing remains high. A few of the fundamental challenges in materials processing confronting the community are improving the quality of the surface finish, eliminating residual stress, controlling local composition and microstructure, achieving fine feature size and dimensional tolerance and accelerating processing speed. Until these challenges are met, the applicability of LM and its commercialization will be restricted. Sustained scientific activity in LM has advanced over the past decade into many different areas of manufacturing and has enabled exploration of novel processes and development of hybrid processes. The research community of today has the opportunity to shape the future direction of science research to realize the full potential of LM.

Photonic crystals are of interest for GHz transmission applications, including rapid switching, GHz filters, and phased-array technology. 3D fabrication by Robocasting enables moldless printing of high solid loading slurries into structures such as the “woodpile” structures used to fabricate dielectric photonic band gap crystals. In this work, tunable dielectric materials were developed and printed into woodpile structures via solid freefrom fabrication (SFF) toward demonstration of tunable photonic crystals. Barium strontium titanate ceramics possess interesting electrical properties including high permittivity, low loss, and high tunability. This paper discusses the processing route and dielectric characterization of (BaxSr1-XTiO3):MgO ceramic composites, toward fabrication of tunable dielectric photonic band gap crystals.

The term Rapid Manufacturing is today very often used as a substitute for Rapid Prototyping, because the manufacturing processes and materials have developed so much that the parts produced with the machines can even be used as functional production parts. For Direct Metal Laser Sintering (DMLS) this was enabled by the introduction of the powders for 20 micron layer thickness; steel-based powder in 2001 and bronze-based powder in 2002. Successful rapid manufacturing with DMLS does not only mean the reduction of layer thickness, but it is a sum of many factors that had to be optimized in order to make the process work with the 20 micron layer thickness: the metal powder behavior in very thin layers is not the same as with thicker layers, the demands for the support structures are higher and the possibility of using multiples of the layer thickness gives additional freedom. By optimizing the process parameters the UTS values for the steel-based powder increased up to 600 MPa and for the bronze-based powder up to 400 MPa. At the same time the surface roughness (Ra) values after shot peening were 3 microns and 2 microns, respectively. Although using thinner layers also increases the building time the advantage is gained in drastically reduced finishing times due to increased surface quality and detail resolution. Typical geometries produced by DMLS are difficult-to-manufacture components and components typically produced by P/M or even by die-casting. The paper covers the development aspects in both material and process development and also presents some realized case studies.

Microstereolithography is a technology at the interface of the microengineering and rapid prototyping domains. It has evolved from the stereolithography technique, and is also based on a light-induced layer-stacking manufacturing. As the resolution of the microstereolithography technique is far better than the one of rapid prototyping technologies, this technique is of particular interest in the microengineering domain where its 3D capability allows the production of components no other microfabrication technique can create.

The first developments of the microstereolithography technique have started in 1993 and different research teams have developed machines since, using different approaches. This paper reviews the major microstereolithography processes developed until now.

Microstereolithography is starting to be a commercially available manufacturing process. As the market for miniaturized products grows rapidly, there is an increasing need for highresolution small size prototype parts. If the production of small mechanical components is the first commercial application of microstereolithography, this technology can also produce useful components for the microrobotic, microfluidic, microsystems and biomedical fields. Current research in the microstereolithography field is focused on using ceramic composites as material to manufacture complex three-dimensional parts that can be sintered to produce pure alumina microcomponents.