[Show abstract][Hide abstract] ABSTRACT: This paper reports the novel design, fabrication and testing of a chip-level-assembled comb-drive XYZ-microstage that produces large displacements into X-, Y-, and Z-directions for the three-dimensional scanning stage of magnetic resonance force microscopy. The main parts of the XYZ-microstage, consisting of a comb-drive XY-microstage, two comb-drive Z-microstages and a bottom silicon base substrate, are assembled together by using micro manipulators. Mechanical springs are used to realize the electrical connections between the XY-microstage and the Z-microstages. It is demonstrated that the assembled XYZ-microstage can achieve large displacements of 25.2 μm in X direction, 20.4 μm in Y direction and 58.5 μm in Z direction. Also, the fabricated Z-microstage integrated with capacitive displacement sensors is installed into a vacuum chamber equipped with a liquid nitrogen cooling stage to evaluate the actuation performance at low temperatures. A maximum displacement of ∼60 μm without any degradation is obtained in the Z-microstage at 77.6 K.
[Show abstract][Hide abstract] ABSTRACT: Resonant sensors for ultimate sensing are developed. By scaling down, the sensitivity of a magnetic resonance force microscopy probe is improved, and three-dimensional imaging of radical density in a poly-10-(4-vinylbenzyl)-10H-phenothiazine particle is demonstrated at room temperature. Also resonant thermal sensor with a microchannel is developed and applied to detect heat from a single brawn fat cell.
[Show abstract][Hide abstract] ABSTRACT: A micro fluidic chamber with 178 nm-thick single crystal Si windows on a micro channel has been developed. Because of these thin windows, the aquatic sample inside of the channel can be observed by scanning electron microscopy. Secondary electrons from a sample in the channel are able to be detected in vacuum with an acceleration voltage of 15 kV, where the emission current is 75 μA. The micro fluidic chamber is possibly applied to cell imaging via the Si thin window in vacuum using magnetic resonance force microscopy.
No preview · Article · Feb 2015 · Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)
[Show abstract][Hide abstract] ABSTRACT: We present the fabrication and characterization of a silicon micromirror with carbon nanotubes (CNTs)-nickel (Ni) composite beams, and evaluate the mechanical stability of the micromirror in terms of resonant frequency. A novel electroplating method is developed for the synthesis of the CNTs-Ni composite. The weight fraction of the CNTs in the electroplated composite is 2.6 wt%, and the ultramicroindentation hardness of the composite is 18.6 GPa. The maximum variation of the resonant frequency of the fabricated micromirror during a long term stability test is approximately 0.25%, and its scanning angle is approximately 20°. It shows the potential ability of the CNTs-Ni composite for micromechanical elements application.
No preview · Article · Feb 2015 · Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)
[Show abstract][Hide abstract] ABSTRACT: In this research, we report the novel design, fabrication and testing of an assembled comb-drive XYZ-microstage that produces highly decoupled motions into X-, Y-, and Z-directions for the three-dimensional (3D) scanning stage of magnetic resonance force microscopy. The XYZ-microstage based on assembling technology consists of three separated parts, i.e., a comb-drive XY-microstage, two comb-drive Z-microstages and a bottom silicon base substrate. The separated parts are assembled together by using micro manipulators and a guide block of stainless steel. It is demonstrated that the assembled XYZ-microstage can achieve large displacements of 25.2 μm in X direction, 20.4 μm in Y direction and 58.5 μm in Z direction.
Full-text · Article · Feb 2015 · Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)
[Show abstract][Hide abstract] ABSTRACT: In this paper, we present the fabrication and characterization of a silicon micromirror with carbon nanotubes (CNTs)-nickel (Ni) nanocomposite beams, and evaluate the mechanical stability of the micromirror in terms of resonant frequency. A novel electroplating method is developed for synthesis of the CNTs-Ni nanocomposite. CNTs are pretreated to have positive charges on their surface and added into a Ni electroplating solution to form a CNTs-Ni nanocomposite electroplating suspension. The weight fraction of the CNT in the electroplated nanocomposite is 9.1 wt%, and the ultramicroindentation hardness is 13 GPa. The mechanical strengthening improvement is found in the nanocomposite in comparison with a Ni film. The maximum variation of the resonant frequency of the micromirror during a long term stability test is about 0.4%, and its scanning angle is about 11°. It shows the potential ability of the CNTs-Ni nanocomposite with proper design for microstructure application.
[Show abstract][Hide abstract] ABSTRACT: Silicon nanowires have attracted considerable attention due to their excellent mechanical and electrical properties and widely investigated for various applications. One of the exciting applications is magnetic resonance force microscopy (MRFM), which requires a high sensitive probe for three-dimensional imaging of spin densities. In this study, we have fabricated a 160 nm-wide and 52 μm-long Si nanowire probe with a Si mirror and Ni magnet from a silicon-on-insulator wafer. The nanowire is suitable structure as the probe for a detection of MRFM. The probe shows a resonance frequency of 8.007 kHz and a Q factor of approximately 5000. Two-dimensional force mapping based on electron spin resonance has been demonstrated using the fabricated nanowire probe.
No preview · Article · Jan 2014 · IEEJ Transactions on Sensors and Micromachines
[Show abstract][Hide abstract] ABSTRACT: A thin film of boron nitride is synthesized on a Si substrate using BCl3 and NH3 as source gases, by thermal chemical vapor deposition. Cubic boron nitride (c-BN) is preferentially synthesized using a Fe thin film. The c-BN film exhibits negative electron affinity. A gated silicon field emitter array coated with a c-BN thin film for multi electron beam lithography is developed. Large emission current can be achieved in BN-coated Si emitter.
[Show abstract][Hide abstract] ABSTRACT: A novel thermoelectric energy generator, which is based on pyroelectric power generation caused by periodic temperature change of a ferroelectric material, is developed. A bulk lead-zirconate-titanate (PZT) ceramic is attached on a bimetal disk. This bimetal disk is placed between heat and cold sources, which causes reciprocatory motion between the heat and cold sources. The temperature of the PZT ceramic is periodically changed due to contact heat transfer, which produces pyroelectric current. Maximum output power of 1.1 nW is obtained with the reciprocation frequency of 1.7 Hz when temperature difference is 247°C.
[Show abstract][Hide abstract] ABSTRACT: A miniature Fourier transform infrared spectrometer (FTIR) is designed and fabricated. The spectrometer consists of an electrostatically-driven Si wishbone interferometer (size: 8 × 8 mm2), Si capacitive displacement sensor, light source with an aperture, and detector. Three-dimensional Si micromirror is assembled on the interferometer. The miniature FTIR operates in mid-infrared range, and multi gas detection including CO2 and water has been demonstrated using this miniaturized FTIR.
[Show abstract][Hide abstract] ABSTRACT: In this paper, silicon resonators were hermetically packaged on basis of anodic bonding of Si and LTCC (Low Temperature Co-fired ceramic) substrates. This research aims at developing the integration technology of the resonator on LSI (Large Scale Integration) for application of a timing device. The structures of the resonators were transferred onto the LTCC substrate using the anodic bonding of silicon and LTCC for electrical interconnections. Then the resonator structures were packaged hermetically by the second anodic bonding of silicon and Tempax glass for encapsulation. The device can be directly bonded to LSI.
[Show abstract][Hide abstract] ABSTRACT: An optically controllable photocathode array made of Si with carbon nanotubes (CNTs) has been developed. The CNTs were grown on apex of Si tips with pn junction. The Si tips were formed on a Si membrane. Laser intensity dependence on IV characteristics of this photo cathode array has been measured. Electron emission can be switched on by laser irradiation, and the emission current also can be controlled by intensity of irradiated laser. Optical switching of electron emission had been successfully demonstrated.
[Show abstract][Hide abstract] ABSTRACT: A moving-magnet-type 2-axis MEMS scanner with a rotation angle detector has been developed. The fabricated MEMS scanner demonstrated a raster scan and 2-axis rotation angles detection with one Hall sensor.
[Show abstract][Hide abstract] ABSTRACT: This Letter reports on the deposition of a conductivity-switching polyimide film as a recording medium formed by molecular layer deposition (MLD). It also reports on the electrical modification on it using a scanning probe microscope (SPM). The polyimide film is uniformly deposited on an Au surface by MLD. As the result of the electrical modification, highly conductive dots pattern with a narrow pitch of approximately 50 nm is successfully defined by applying pulsed voltages. The current ratio of the electrical modified area to unmodified area reached 300 at least.
No preview · Article · Nov 2010 · Micro & Nano Letters
[Show abstract][Hide abstract] ABSTRACT: In this paper, we report the design and fabrication of a scanning near-field optical microscopy (SNOM) probe with integrated zinc oxide photoconductive antennas for local terahertz (THz) spectroscopy. Photoconductive antennas are used as a THz pulse emitter and detector. A pyramidal tip with an aperture formed at the end of a silicon cantilever is used as an SNOM head.
No preview · Article · Jan 2010 · Sensors and Materials
[Show abstract][Hide abstract] ABSTRACT: A time-of-flight scanning force microscope (SFM) probe with an ability to switch the measurement mode using the electrostatically switching mechanism is designed, fabricated and demonstrated the performance of it. In order to achieve surface observation and chemical analysis simultaneously for imaging the chemical property of a material surface, this probe can switch the positions of the cantilever between SFM mode and time-of-flight mass analysis (TOF-MA) mode by integrating a couple of electrostatic actuator with curved electrode. This mechanism will be applied to pick up an atom or molecule under SFM mode, then emits them to TOF mass analyzer using field evaporation for analyzing its mass in TOF-MA mode. To switch the cantilever position at TOF-MA mode, the fabricated probe generated the 255 mum of maximum displacement at the end of cantilever at an actuation voltage of 180 V. The cantilever is attracted with the electrode according to the curved shape using electrostatically pull-in effect. The front edge of the cantilever was aligned in front of integrated extraction electrode for emitting chemical species. In SFM mode, the cantilever was also attracted to another electrode. The fundamental resonant frequency of the cantilever is increased from 1.8 kHz to 6.8 kHz before and after actuation. A calculated spring constant is changed from 0.05 N/m to 0.34 N/m.
[Show abstract][Hide abstract] ABSTRACT: This paper presents the design, fabrication and characterization method of piezoresistive nanocantilevers for ultra-sensitive force detection application. A shallow boron-doped layer as thin as 40 nm is achieved using spin-on diffusion. The piezoresistive nanocantilevers are patterned by electron beam (EB) lithography and fast atom beam (FAB) etching. The resonance response of the nanocantilevers is characterized by both optical readout using a laser Doppler vibrometer and piezoresistive self-detection. A soft spring effect is detected in the nanocantilevers.
No preview · Article · Jul 2008 · Measurement Science and Technology
[Show abstract][Hide abstract] ABSTRACT: In this paper, we have proposed, fabricated and characterized a parallel electron beam micro-column with single-stranded carbon nanotube (CNT) filed emitters. The integrated micro-column consists of a self-aligned CNT field emitter array (FEA), and a multi-layered electrostatic Si focusing lens array. In our design, the emitters, gate and electrostatic lens array are electrically isolated, and each source can be controlled individually. Electron emission performance of the fabricated CNT/Si emitter was characterized. The best turn-on fields, defined as the field required to generate an emission current of 1 nA, were approximately 6 V. When applying a gate voltage of 100 V, a 110 nA anode current is measured. It is seen that CNT/Si emitter showed low threshold voltage; however, the emission current fluctuation was high during high voltage operation.
[Show abstract][Hide abstract] ABSTRACT: In this paper, a novel probe with an integrated radio frequency single-electron transistor (rf-SET) for magnetic resonance force microscopy operated at low temperatures is proposed and fabricated. By using the charge sensitivity of the rf-SET, the displacement of a cantilever can be detected from the capacitance variation between the quantum island and the gate formed on the cantilever with high sensitivity. The rf-SET using a Cr thin film isolated with tunneling junction of a thin silicon dioxide film was fabricated on the basis of electron beam lithography and self-aligned island formation.
[Show abstract][Hide abstract] ABSTRACT: Integration of metals and semiconductors having three- or sixfold symmetry on device-oriented [i.e., (001)] silicon wafers, which have fourfold symmetry, has been a long-standing challenge. The authors demonstrate that, by using symmetry-converted (111) silicon on insulator, wurtzite-structure gallium nitride, which has threefold symmetry, can be integrated with Si(001). The stability of the symmetry-converted Si(111) layer makes this technique appealing to the commercial integration of wide-ranging important materials onto Si(001) base wafers. c 2007 American Institute of Physics.
Full-text · Article · Jun 2007 · Applied Physics Letters