This article investigates the mechanism of brittle-ductile deformation and fracture for sintered silver (s-Ag) film by means of in situ scanning electron microscopy (SEM) uniaxial tensile loading at room temperature (RT) and 300 °C. The s-Ag film specimen originating from nano-Ag paste, including 18-nm-diameter Ag particles, is sintered at 300 °C under 60-MPa pressure. A precrack and slope surface are fabricated in the s-Ag specimen with a focused ion beam (FIB) for conducting in situ SEM observation during applied tensile loading. A local in situ SEM observation area is set to $8\times 5\,\,\mu \text{m}^{2}$ around the specimen's precrack tip. At RT, the s-Ag specimen shows a brittle fracture, whereas at 300 °C, the s-Ag specimen shows a ductile fracture with microstructural changes involving pore growth and grain boundary degradation. However, fracture surface morphology provides the opposite impression, where the fracture surface at 300 °C looks like an intergranular fracture. Finite-element analyses (FEAs) and electron backscatter diffraction (EBSD) suggest that the stress in the plastic region can accelerate the microstructure changes. The Ag atomic gliding speed at the grain boundary determines brittle-ductile deformation and fracture characteristics in s-Ag film. The reason why fracture surface impression differs from actual deformation is discussed using detailed snapshots during the fracture of s-Ag film at 300 °C.
This paper describes design and fabrication of a Ti-Ni shape-memory alloy (SMA) film-actuated single crystal silicon (SCS) multi-probe device utilized for scanning probe nano-lithography (SPNL). This research focuses on the development of the device that can realize fabrication of a nanoscale mask pattern on a few millimeters square area. The designed device consists of Ti-Ni SMA film-actuated 8 times 8 writing-probes with an Au film-coated tip, and 2 times 2 tilt-adjustment probes with a piezo-resistive sensor. The SMA actuation mechanism yields a contact or non-contact state between a probe-tip and a sample surface, which indicates that SPNL turns on or off . The tilt-adjustment system can make a spacing between the device and a wafer constant. We have succeeded in fabricating the SPNL multi-probe array device, which has the potential for realization of accurate mask patterning on a few millimeters square area.
This paper describes fabrication, characterization, and demonstration of a novel active micro-catheter with Ti-Ni shape memory alloy (SMA) actuators for wide range of forward-looking area to remedy diseased area inside a blood vessel. The developed active micro-catheter consists of eight Ti-Ni SMA spring actuators for catheter actuation, an ultrasonic piezoelectric transducer for forward-looking, a guide wire, a polyurethane tube for catheter coating, and spiral wirings for various flexure motions of catheter by Ti-Ni SMA actuators. The size of the catheter is 3.5 mm in diameter and 60 mm in length of the sum of transducer and actuator sections. Ti-Ni SMA springs were fabricated from a Ti-50at.% Ni sheet by electrochemical etching with a mixed solution of ethanol and lithium chloride. The micro-catheter was assembled by hand under a stereomicroscope. The tip of the produced micro-catheter was able to bend toward at least eight directions by controlling an applied current to Ti-Ni SMA springs. We have demonstrated the effectiveness of the active micro-catheter by carrying out experiments on blood vessels in a small animal.
This paper describes the development of a bimorph-actuated twin-probe device utilized for uniaxial tensile test to measure tensile elongation of a film specimen. The device consists of two sets of microscale cantilever probes with piezoresistive sensor to detect the position of two gauge marks on a specimen, and multiple pairs of bimorph actuators to produce in-plane motion for scanning those marks. By Joule's heating, the bimorph actuators connecting two cantilever probes are able to move along the tensile direction. When those probes climb the gauge marks having convex line structure, the sensor signals originating from the piezoresistive effect are output by the cantilever's deflection. The elongation of a tensile specimen can be calculated from the moving velocity of cantilever probes and the time difference between two sensor signals. The performance of the device produced through conventional micromachining technologies was investigated. Elongation of single-crystal silicon (SCS) film specimen was measured during uniaxial tensile loading. The mean Young's modulus of 165.1 GPa which was measured by using the device was in good agreement with the analytical value. The proposed bimorph-actuated twin-probe device would be useful for measuring elongation of a film specimen during the tensile test.
Abstract This paper describes the influence of Zeta potential on pore arrangement in porous silica and alumina particles. The ultrasonic atomization method is utilized to produce silica or alumina porous particles from the slurry including the oxide nanoparticles and polystyrene latex (PSL) particles. The whole particle shape and pore arrangement are determined by the combination of the sign of Zeta potential between the oxide nanoparticles and PSL particles as well as the mixture ratio of the oxide to PSL. The mechanism is discussed through observation with cross-sectional scanning electron microscopy.
This research makes clear the temperature effect on mechanical properties of micro/nano scale Si beams by using Atomic Force Microscope (AFM). The Si and SiO_2 beam were fabricated on a Si diaphragm by means of field-enhanced anodization with AFM and anisotropic etching. The beams were approximately 200-800nm in width and 255nm in thickness. As a result of bending tests, bending strength and Young's modulus of Si beam in the <110> direction decreased with increasing temperature ranging from 295K to 573K.
This paper reports on two types of fabrication methods for Si nanowires (NWs) using focused ion beam (FIB), photolithography, TMAH anisotropic wet-etching, and sacrificial oxidation. Type A specimens made from silicon-on-nothing (SON) membranes are produced by FIB system's probe manipulation and film deposition functions. The mean Young's modulus of FIB-fabricated NWs evaluated by tensile testing in SEM using electrostatic actuated MEMS device is 129 GPa. After vacuum annealing, the Young's modulus is increased to 168 GPa. Type B specimens are produced by wire-thinning technique using sacrificial oxidation and oxide film removal. We succeeded in making freestanding bridge Si NW with the width of 76 nm.
