Michael J. Renn

Particle manipulation and surface patterning by laser guidance

Laser-induced forces are used to manipulate atoms, clusters, and micron-sized particles in hollow optical fibers. Laser light (400 mW, 800 nm) is guided in a low-order grazing incidence mode in glass capillaries. The optical field in the fiber generates gradient and scattering forces which simultaneously draw particles to the center of the hollow region and push them along the fiber axis. Dielectric, semiconductor, and metal particles in the size range of 9 μm–50 nm have been guided in gas- and liquid-filled fibers. Rb atoms are guided in evacuated fiber for up to 15 cm. Used alone or in conjunction with traditional methods, laser guidance is attractive for direct-write lithography. Arbitrary surface patterns can be created under ambient conditions with potential write speeds exceeding 106 particles/s and placement accuracy approaching 50 nm (assuming a 1 W laser, 100 nm Ge particles, and fiber filled with Ar at 760 Torr). Anisotropic optical forces resulting from particle shape anisotropy act to orient p...

Printing conformal electronics on 3D structures with Aerosol Jet technology

Fabrication of 3D mechanical structures is sometimes achieved by layer-wise printing of inks and resins in conjunction with treatments such as photonic curing and laser sintering. The non-treated material is typically dissolved leaving the final 3D part. Such techniques are generally limited to a single material which makes it difficult to integrate high resolution, conformal electronics over part surfaces. In this paper, we demonstrate a novel, non-contact technique for printing conformal circuits called Aerosol Jet printing. This technique creates a collimated jet of aerosol droplets that extend 2-5 mm from the nozzle to the target. The deposited features can be as small as 10 microns or as large as a centimeter wide. A variety of materials can be printed such as metal nanoparticle inks, polymers, adhesives, ceramics, and bio-active matter. The print head direction and XYZ positioning is controlled by CAD/CAM software which allows conformal printing onto 3D substrates having a high level of surface topography. For example, metallic traces can be printed into 3D shapes such as trenches and via holes, as well as onto sidewalls and convex and concave surfaces. We discuss the fabrication of a conformal phase array antenna, embedded circuitry and sensors, and electronic packaging.

Flow- and Laser-Guided Direct Write of Electronic and Biological Components

Laser-guided direct writing is an emerging technology for high-throughput deposition of micrometer and submicrometer sized particles. It is a process developed for direct writing electronic components and mechanical structures with extreme accuracies and in a maskless process. Laser-guided direct writing is a simple system that can be set up at low cost and deposit virtually any material with micrometer scale accuracy such as ceramics, oxides, and biological materials. The intriguing potential of direct-write technologies is to enable the combination of todays disparate electronics manufacturing processes into an integrated production system. This system can manufacture the printed circuit board and necessary components, and can perform the packaging and assembly functions, thus eliminating many costly steps and serving as the gateway to three dimensional electronic systems and hybrid electronic or biological systems. The chapter summarizes recent results including micron-scale deposition techniques, material developments, laser treatments of various metals and dielectrics, and component performance.

Laser Guided Direct Writing

Laser-induced optical forces are used to guide and deposit 100 nm - 10 µm diameter particles onto solid surfaces in a process called laser-guided direct-writing . Nearly any particulate material, including both biological and electronic materials, can be manipulated and deposited with micrometer accuracy. Potential applications include three-dimensional cell patterning for tissue engineering, hybrid biological and electronic device construction, and biochip array fabrication

Nano- and microscale manipulation of biological particles by laser-guided direct writing

Tissue engineering has shown great potential for solving health problems through replacing or repairing malfunctioning tissue with functional constructs of living cells and associated molecules. To realize this potential, complicated cell-cell interactions both in the macro scale and micro scale need to be understood.

Direct writing of materials by laser guidance

Summary form only given. We use optical forces to guide aerosol particles through hollow-core optical fibers. A wide variety of materials can be manipulated including solid metal, dielectric, and semiconductor particles as well as liquid droplets. The guided particles emerge from the fiber in a narrow beam and can be deposited on a substrate placed near the fiber output tip. By translating the substrate during particle deposition arbitrary structures of lines and dots can be constructed. The deposition conforms to the substrate curvature and the structures can be defined with micron resolution. The laser beam is intense enough to melt many types of particles during delivery to the substrate. The resulting structures are fully dense and well adhered.

Morphology-dependent resonance at small size parameter

Summary form only given. Morphology-dependent resonances (MDR) have previously been observed in dye-doped microdroplets above size parameter 30. We report a novel laser trapping technique which allows manipulation of droplets as small as 50 nm radius, and observations of cavity quantum enhanced MDR between size parameter 10 to 30. Below size parameter 15, we observe an increase in MDR linewidth and corresponding decrease in peak intensity with decreasing size parameter.