An integrated laser blood flowmeter

We have constructed a very small and lightweight blood flowmeter using micromachining and surface mounting techniques for a wearable health monitoring system. The hybrid integrated structure of the optical system incorporates a InGaAsP-InP distributed feedback laser diode (DFB-LD) with a wavelength of 1310 nm, an edge-illuminated photodiode (PD) and a polyimide waveguide on silicon substrate (2 mm /spl times/ 3 mm). This integrated flowmeter can be positioned directly on the tissue and permits real-time monitoring of capillary microcirculation. In-vivo measurements of blood perfusion in a finger confirm the feasibility of the blood flowmeter.     

Monolithic-integrated microlaser encoder

We have developed an extremely small integrated microencoder whose sides are less than 1 mm long. It is 1/100 the size of conventional encoders. This microencoder consists of a laser diode, monolithic photodiodes, and fluorinated polyimide waveguides with total internal reflection mirrors. The instrument can measure the relative displacement between a grating scale and the encoder with a resolution of the order of 0.01 mum; it can also determine the direction in which the scale is moving. By using the two beams that were emitted from the two etched mirrors of the laser diode, by monolithic integration of the waveguide and photodiodes, and by fabrication of a step at the edge of the waveguide, we were able to eliminate conventional bulky optical components such as the beam splitter, the quarter-wavelength plate, bulky mirrors, and bulky photodetectors.     

Monolithically integrated optical displacement sensor based on triangulation and optical beam deflection

A monolithically integrated optical displacement sensor based on triangulation and optical beam deflection is reported. This sensor is simple and consists of only a laser diode, a polyimide waveguide, and a split detector (a pair of photodiodes) upon a GaAs substrate. The resultant prototype device is extremely small (750 mum x 800 mum). Experiments have shown that this sensor can measure the displacement of a mirror with resolution of better than 4 nm. Additionally, we have experimentally demonstrated both axial and lateral displacement measurements when we used a cylindrical micromirror (diameter, 125 mum) as a movable external object.     

A three-dimensional MEMS optical switching module having 100 input and 100 output ports

This paper describes an optical switching module based on microelectromechanical systems (MEMS) two-axis tilt mirror arrays and low-cost highly accurate free-space optics. The MEMS mirror arrays are integrated on single-crystal silicon wafers and provide reliable switching operation at a low driving voltage. The free-space optics consists of two-dimensional optical fiber and microlens arrays based on low-cost and highly accurate polymer-based components. They provide a compact switching module (approximately 80/spl times/60/spl times/35 mm [170 cc]) and are assembled passively by using dowel pins. A prototype switch module with 100-ch optical fiber I/O has a low coupling loss of 4.0 dB, a low crosstalk within -60 dB, and switching time of 3 ms.     

Integrated microlaser Doppler velocimeter

We have developed a microlaser Doppler velocimeter in which the laser diode, photodiode, and optical waveguide are monolithically integrated on a GaAs substrate. This integration eliminates the difficult optical alignment and susceptibility to environmental disturbances which are disadvantages of the conventional laser Doppler velocimeter. Our velocimeter showed good linearity between relative velocity and output frequency, and it can detect very low velocities of less than 5 μm/s. It can also measure the flow speed of a liquid containing particles. Moreover, the addition of a step at the end of the waveguide and one more photodiode enables the phase difference to be used for directional discrimination     

Production of a highly charged uranium ion beam with RIKEN superconducting electron cyclotron resonance ion source

A highly charged uranium (U) ion beam is produced from the RIKEN superconducting electron cyclotron resonance ion source using 18 and 28 GHz microwaves. The sputtering method is used to produce this U ion beam. The beam intensity is strongly dependent on the rod position and sputtering voltage. We observe that the emittance of U(35+) for 28 GHz microwaves is almost the same as that for 18 GHz microwaves. It seems that the beam intensity of U ions produced using 28 GHz microwaves is higher than that produced using 18 GHz microwaves at the same Radio Frequency (RF) power.     

Low-Temperature Bonding of Laser Diode Chips on Silicon Substrates Using Plasma Activation of Au Films

A low-temperature bonding of vertical-cavity surface-emitting laser (VCSEL) chips on Si substrates was achieved by using plasma activation of Au films. After the surfaces of Au films were cleaned using an Ar radio frequency plasma, bonding was carried out by contact in ambient air with applied static pressure. The experimental results showed that surface morphological change (the reduction of asperity width) as well as removal of adsorbed organic contaminants by plasma treatment significantly improved the quality of joints. At a bonding temperature of 100degC, the die-shear strength exceeded the failure criteria of MIL-STD-883.     

Optimization of magnetic field configuration for the production of Ar ions from RIKEN 18 GHz ECR ion source

We successfully extracted a 1.9 mAAr⁸⁺ ion beam and a 1 mAAr⁹⁺ ion beam from the RIKEN 18 GHz ECR ion source at the extraction voltage of 17 kV and the microwave power of 700–800 W. To obtain these intensities, we optimized the magnetic field configuration and the plasma electrode position.     

Highly accurate and quick bonding of a laser-diode chip onto a planar lightwave circuit

A method for accurately and quickly bonding a planar lightwaveguide circuit (PLC) and a laser diode is proposed. It is based on simultaneous auto-focusing on marks fabricated on the PLC and laser diode. Bonding equipment constructed to implement the method achieves alignment accuracy of ± 1 μm and greatly reduces the turn-around-time, i.e., the time from when the laser diode is picked up by the tweezers to completion of the bonding process.     

The protein tyrosine kinase Fyn activates transcription from the HIV promoter via activation of NF kappa B-like DNA-binding proteins

Protein tyrosine kinase p59fyn (Fyn) associates with the TCR-CD3 complex, which suggests that Fyn plays a significant role in the signal transduction involving TCR complex. In addition to cellular genes, viral promoters such as the HIV long terminal repeat (LTR) are also activated upon T cell activation. To elucidate the functional significance of Fyn in the expression of viral promoters, we transfected a Fyn-expression vector together with a reporter plasmid containing the chloramphenicol acetyltransferase gene driven by HIV LTR into a human T cell line, Jurkat. In this assay, Fyn stimulated the promoter in HIV LTR when the transfected cells were treated with both concanavalin A and PMA as an antigen-mimic stimulation. This activation required the intact SH2 domain of Fyn. Mutational analysis of HIV LTR showed that the NF kappa B binding sites were responsible for this effect. Electrophoretic mobility shift assays and UV cross-linking experiments showed that activation of T cells by anti-CD3 antibody induced four kappa B-binding proteins (50, 60, 65 and 100 kDa) in Fyn-overexpressing cells more efficiently than in the parental cells. Our results suggested that Fyn was able to regulate expression of a subset of genes via kappa B-binding proteins upon T cell activation.