Invertible logic using a probabilistic magnetoresistive device model has been recently presented that can compute functions in bidirectional ways and solve several problems quickly, such as factorization and combinational optimization. In this article, we present a design framework for invertible logic circuits. Our approach makes use of linear programming to create a Hamiltonian library with the minimum number of nodes for small invertible-logic functions. In addition, as the device model is approximated based on stochastic computing in synthesizable SystemVerilog, a faster simulation using the compiled SystemC binary is realized than a conventional SPICE-level simulation and is verified using field-programmable gate array (FPGA) as prototyping. Using our design framework, several invertible-logic circuits are designed and emulated (verified) in SystemC, exhibiting five order-of-magnitude faster simulation than conventional work.

This article introduces high-throughput/low-energy true random number generators (TRNGs) based on CMOS and three-terminal magnetic tunnel junction (MTJ) devices. MTJs are fast and probabilistic switching devices, which can be used as random number sources for TRNGs. However, as the switching probability is quite sensitive to the write current given to MTJs, precise closed-loop control is necessary. Thus, a high-complexity current control circuit is required, such as high precision digital-to-analog converters (DACs), occupying large area and causing large energy dissipation. In order to address the issue, we propose a multi-voltage/current (V/I) converter capable of multilevel coarse current switching and fine adjusting within each level. The fine adjusting can be done by DACs with fewer bits, resulting in much smaller size and energy dissipation than a conventional single-V/I converter. In addition, a multiple-writing scheme for three-terminal MTJs is proposed for increasing the throughput while maintaining the write power. The proposed TRNGs are designed using TSMC 65-nm CMOS and a threeterminal MTJ model that achieves a throughput of 333 Mb/s, an energy dissipation of 0.66 pJ/bit and an area of 2040 μm2. This result exhibits a 5× throughput, a 93% energy reduction and an 86% area reduction in comparison with a conventional CMOS/MTJ-based TRNG.

In this work we show that implementation of closed-loop control to silicon nanotweezers improves the sensitivity of the tool for mechanical characterization of biological molecules. Micromachined tweezers have already been used for the characterization of mechanical properties of DNA molecules [1] as well as for the sensing of enzymatic reactions on DNA bundle [2], [3]. However the resolution of the experiments does not allow the sensing on single molecules. Hereafter we show theoretically and experimentally that, reducing the resonance frequency of the system by the implementation of a state feedback, the sensitivity to stiffness variation is enhanced. Such improvement leads to better resolution for detection of enzymatic reactions on DNA [4].

Despite the benefits of miniaturized devices, handling of tiny amount of molecules became a great challenge. Direct transport, similar to the one in intracellular transport, is a way to cope with the problem of transporting tiny amount of materials. Using motor proteins, i.e. kinesin, and the corresponding rail structures, i.e. microtubules, provides powerful building blocks for a nanotransport system. However, it is extremely difficult to construct a complex transport network to allow arbitrary design. Here, we have developed a MEMS-based molecular handling system for the pick-and-place assembly of individual microtubules. The technology enabled us to build a bio/MEMS hybrid system composed of multidirectional microtubule networks along which kinesin molecules move. Using MEMS tweezers to manipulate a single microtubule enables precise positioning and full control in functional orientation and stacking order. As a result, kinesin-coated beads can be transported along the route specifically assembled for them to follow. Direct transport of target molecules can be achieved by loading the beads with the molecules to carry. “Bottom-up” functionalities of biomaterials are incorporated with micro fluidic devices by the handling capabilities of the “top-down” approach.

We developed a pneumatic conveyance system that consists of an array of micro air valves fabricated by MEMS technology. The array of 560 micro actuators successfully conveyed a small silicon chip, which was 3 mm/spl times/3 mm/spl times/100 /spl mu/m in size and 2 mg in weight. The chip was transferred to the force equilibrium point, which was generated by the arrayed actuators. In addition, we proposed a control method for the system; in this method, the equilibrium point is moved in order to transfer the object on it We also conveyed a small plastic chip, which was 5 mm /spl times/ 5 mm /spl times/ 1 mm in size and 38 mg in weight. In this case, efficient conveyance was achieved by detecting the object edge and applying tilted air jets to it. A full control of two-dimensional conveyance is under investigation. The control circuit chip was developed; the circuit is an array of cells that have optical sensors and processors. Distributed information processing by the cooperation of cells enabled detection of the shape of the conveyed object. Our future goal is to assemble the conveyance system with the circuit, and to realize the autonomous distributed micro conveyance system.

Responsive communication protocols must incorporate both real-time and fault-tolerant properties. In this paper, we propose a new method for detecting design faults in specifications of responsive communication protocols based on real-time temporal logic. We also present a case study where a connection establishment protocol for a plant control system is dealt with.

Research and development in microelectromechanical systems (MEMS) have made remarkable progress since 1988, when an electrostatic micromotor the size of a human hair was first operated successfully. Since then, many types of microactuators utilizing various driving forces and mechanisms have been developed. Distinctive features of MEMS (miniaturization, multiplicity of components, and the integration of microelectronics) have led to promising application areas such as fluidic microsystems. In the future, MEMS promises to make contributions to the society of the twenty-first century in three broad areas: (1) offering easier access to information, (2) making human lifestyles more compatible with the environment, and (3) improving people's social welfare. This paper will discuss some of the technological issues pertaining to microactuators, micromachines, and the future development of MEMS.

We have proposed the concept of distributed micro motion systems (DMMS) in order to coordinate simple motions of many microactuators arranged on a wafer so as to perform a more complicated task. A two-dimensional conveyance system in a plane is studied as an example of DMMS. A system design has been presented with the aim of controlling many microactuators in a similar way as the cellular automaton. In this paper, we focus on a microactuator and define a micro-axel as an elemental unit of DMMS. We have previously reported the development and operation of a one-dimensional conveyance system using a fluidic micro-axel array. We improved the conveyance system and developed a two-dimensional system to perform a positioning task. This paper describes the design, fabrication, and operation of a fluidic micro-axel array for the two-dimensional conveyance system. The experiments to convey objects to the fixed desired position by the fabricated two-dimensional conveyance system performed successfully.

The progress of ITU-T and ANSI standards on SDH/SONET is accelerating the evolution of transmission systems all over the world. The advanced operation administration and maintenance (OAM) functions it provides makes it possible to create a self healing ring network which protects against failure. This self-healing ring consists of add/drop multiplexers (ADM's). The switch in the ADM plays an important role in achieving self-healing operation. In this paper, self-healing ring architecture and operations are analyzed in order to determine the requirements for the ADM switch. On the basis of this result, new space division switching methods, which significantly reduce the amount of hardware needed, are proposed. A parallel processing architecture which makes it possible to develop a low-cost large-scale switch is also devised. Finally, a developed switch LSI chip is presented. Combining two identical chips with the proposed parallel processing architecture, a 32/spl times/32 STS-3 switch (5 Gb/s throughput) with an STS-1 time slot interchange (TSI) function is realized.

We have previously reported the development and operation of a lateral tunneling unit (LTU), a micromachined device which can control the magnitude of a tunneling current passing through a vacuum gap by adjusting the distance of the gap. The amplitude of the actuator driving voltage necessary to vary the current certain range was much larger than the theoretically expected value. Its cause has been left unclear. We carried out experiments in the air and in ultrahigh vacuum (UHV), in order to determine the mechanism of the disagreement. The results of them indicated that an atomic force affects the behavior of the LTU. The estimated magnitude of the force was so large as not to be neglected compared with the actuation force of the LTU. We increased the rigidity and actuation force over 50 times and achieved stabilization. A guide to design a stable LTU and its controller will be given based on the experimental results.

A conveyance system based on the concept of distributed micromotion systems (DMMSs) fabricated by IC-compatible micromachining processes is proposed. The DMMS consists of many smart modules which have microsensors, microactuators, and controllers. Each module has primary autonomy to determine its motion based on information from surrounding modules. Information processing in DMMS is similar to that in a cellular automaton. The key idea is to coordinate simple motions of microactuators in order to carry objects. As an example, a positioning system that can convey objects to a desired point on a X-Y plane is discussed. The control scheme of the conveyance system and a microactuator that uses controlled air flow to levitate and convey objects are described.>

Various kinds of driving principles are proposed for micro actuators. Electrostatic, superconducting, piezoelectric, and shape-memory alloy actuators are studied, with emphasis on work done in Japan. Electrostatic actuators, a superconducting actuator, an actuator which simulates muscles, a microfluid system with piezoelectric actuators, and a cell fusion system based on a fluid integration circuit are described. Microactuators and the micro machines driven by them are expected to have wide varieties of applications in medical, bioengineering, optics, information machinery, and robotics fields. It is shown that before a practical microsystem is distributed, however, there are still difficulties such as micro sources, packaging, interfacing, reliability, and control of many autonomous systems.>