Jacque Lynn Gabayno

Design and implementation of shape memory alloy-actuated nanotweezers for nanoassembly

Reliable and accurate tools for nanoscale manipulation are constantly sought to complement new breakthroughs in nanomaterials and nanotechnology. In this study, a new design of electrically actuated nanotweezers was developed for manipulation of individual nanowires. The design featured two chemically etched tungsten tips attached to a carbon fiber-reinforced polymer and two shape memory alloy actuators. The shape recovery effect of the spring actuators was exploited as a control mechanism for the bending and relaxation modes of the nanotweezers. This was activated by driving a potential difference of less than 1 V across the coils, which was considerably lower than for electromechanical micro/nanotweezers previously developed. To demonstrate the pick-and-place capability of the system, experiments were implemented inside the vacuum chamber of a JEOL-JSM 6300 SEM. Individual Au nanowires averaging 5–10 µm in length and 200 nm in diameter were assembled on silicon substrates using the tungsten tips to draw initials out of various nanowire shapes such as curls, loops, crosses, and zigzags. With such capability, the nanotweezers may find applications in the manufacturing of complex nanostructures or modification of surface properties of materials.

Development of an optical inspection platform for surface defect detection in touch panel glass

ABSTRACT An optical inspection platform combining parallel image processing with high resolution opto-mechanical module was developed for defect inspection of touch panel glass. Dark field images were acquired using a 12288-pixel line CCD camera with 3.5 µm per pixel resolution and 12 kHz line rate. Key features of the glass surface were analyzed by parallel image processing on combined CPU and GPU platforms. Defect inspection of touch panel glass, which provided 386 megapixel image data per sample, was completed in roughly 5 seconds. High detection rate of surface scratches on the touch panel glass was realized with minimum defects size of about 10 µm after inspection. The implementation of a custom illumination source significantly improved the scattering efficiency on the surface, therefore enhancing the contrast in the acquired images and overall performance of the inspection system.

Thrombolysis based on magnetically-controlled surface-functionalized Fe3O4 nanoparticle

ABSTRACT In this study, the control of magnetic fields to manipulate surface-functionalized Fe3O4 nanoparticles by urokinase coating is investigated for thrombolysis in a microfluidic channel. The urokinase-coated Fe3O4 nanoparticles are characterized using particle size distribution, zeta potential measurement and spectroscopic data. Thrombolytic ratio tests reveal that the efficiency for thrombus cleaning is significantly improved when using magnetically-controlled urokinase-coated Fe3O4 nanoparticles than pure urokinase solution. The average increase in the rate of thrombolysis with the use of urokinase-coated Fe3O4 nanoparticles is about 50%. In vitro thrombolysis test in a microfluidic channel using the coated nanoparticles shows nearly complete removal of thrombus, a result that can be attributed to the clot busting effect of the urokinase as it inhibits the possible formation of blood bolus during the magnetically-activated microablation process. The experiment further demonstrates that a thrombus mass of 10.32 mg in the microchannel is fully removed in about 180 s.

Magnetic Control of Fe3O4 Nanomaterial for Fat Ablation in Microchannel

In this study, surface modification of iron (II, III) oxide Fe3O4 nanoparticles by oleic acid (OA) coating is investigated for the microablation of fat in a microchannel. The nanoparticles are synthesized by the co-precipitation method and then dispersed in organic solvent prior to mixing with the OA. The magnetization, agglomeration, and particle size distribution properties of the OA-coated Fe3O4 nanoparticles are characterized. The surface modification of the Fe3O4 nanoparticles reveals that upon injection into a microchannel, the lipophilicity of the OA coating influences the movement of the nanoparticles across an oil-phase barrier. The motion of the nanoparticles is controlled using an AC magnetic field to induce magnetic torque and a static gradient field to control linear translation. The fat microablation process in a microchannel is demonstrated using an oscillating driving field of less than 1200 Am−1.

Amplification of Ultraviolet Femtosecond Pulse by a Micro-Pulling Down Method-Grown Ce:LiCAF Crystal in a Prismatic Cell-Type, Side-Pumping Configuration

We propose an efficient side-pumping scheme for ultraviolet (UV) femtosecond pulse amplification in micro-pulling-down (µPD) method-grown Ce:LiCAF using a prismatic cell-type configuration. By uniformly illuminating four sides of a 2-mm-diameter and 30-mm-length Brewster-cut, nearly as-grown crystal, the risk of damage is dramatically reduced. Without using a chirp pulse amplifier scheme, UV femtosecond pulse at 290 nm is amplified 4 times with no significant increase to its pulse duration and B-integral. Our results show that a laser-quality, Ce:LiCAF crystal, efficiently grown by the µPD method and pumped in a prismatic-cell type configuration paves new possibilities in providing high energy UV femtosecond pulses.

Magnetic Field-Driven Manipulation System and its Applications in Micromixing and Microablation

This study showcases two independent magnetic manipulation systems to remotely control the movement of Fe3O4 nanomaterial in microfluidic chips. One system utilizes a homogeneous rotating magnetic field to carry out magnetic stirring in 100 μm and 300 μm flow channels. The mixing results of this system revealed that adding Fe3O4 nanoparticles to the solution enhances the efficiency of the micromixer by twice as much that of a device without the nanomaterial. The second manipulation system utilizes oscillating magnetic field for rapid microablation of thrombus in a microchannel. A customizable magnetic platform using 3D-printed material is also constructed. This is proposed as a feasible low-cost and portable magnetic manipulation device that can implement both applications.

Optimized Ce:LiCAF amplifier pumping configurations

Two side-pumping schemes suitable for the development of an ultraviolet femtosecond amplifier system using a Ce3+:LiCaAlF6 crystal are reported. Firstly, a Bethune-type prismatic cell configuration that uniformly illuminates the four sides of a micro-pulling down method-grown crystal is used to amplify 290 nm, femtosecond pulses with no significant increase in pulse duration and B-integral. The second pumping scheme uses a two-side-pumped large crystal. These two side-pumping schemes can pave new possibilities for achieving high-energy ultraviolet femtosecond pulses.

High-resolution optical inspection system for fast detection and classification of surface defects

ABSTRACT A high-resolution automated optical inspection (AOI) system based on parallel computing is developed to achieve fast inspection and classification of surface defects. To perform fast inspection, the AOI apparatus is connected to a central computer which executes image processing instructions in a graphical processing unit. Defect classification is simultaneously implemented with Hu’s moment invariants and back propagation neural (BPN) approach. Experiments on touch panel glass show that using 100 training samples and 1000 cycle iterations in BPN, the accurate classification of surface defects for a 350 × 350 pixels image can be completed in less than 0.1 ms. Moreover, the inspection of a 43 mm × 229 mm sample that yields an 800 megapixel raw data can be completed remarkably fast in less than 3 s. Thus, the AOI system is capable of performing fast, reliable, and fully integrated inspection and classification equipment for in-line measurements.

Bond line thickness and die tilt inspection in die bonding process

Abstract This study focuses upon building an automated inspection system for the in-line measurement of bond-line thickness (BLT) and die tilt in die attachments in the semiconductor packaging process. A prototype of a visual system utilizing the line scan stereo vision technique via two linear CCD cameras has been developed for the die bonding quality inspection. A novel algorithm is proposed for the determination of the 3D coordinates of certain points on an object. The BLT and die tilt of a die attached chip of substrate height 800 μm and cross section 15 × 15 mm2 were measured to be approximately 76.8 μm and 0.00094, respectively. The measurement can be completed within one second. Thus the in-line inspection of die bonding quality can be conducted efficiently using the proposed technique.