Manabu Ataka

Fabrication and operation of polyimide bimorph actuators for a ciliary motion system

In order to extract macroscopic mechanical work out of microelectromechanical systems, we have proposed the concept of distributed micromotion systems (DMMS). The key idea of DMMS is to coordinate simple motions of many microactuators in order to perform a task. Design, fabrication, and operation of a type of DMMS, called a ciliary motion system, are presented. A bimorph thermal actuator using two types of polyimides with different thermal expansion coefficients and a metallic microheater in between them was fabricated. The cantilever-shaped actuator curled up from the substrate owing to the residual stress in polyimides which built up during the cooling process after they were cured at 350 degrees C. It flattened and moved downward by flowing current in the heater. The dimensions of the cantilever were 500 mu m in length, 100 mu m in width, and 6 mu m in thickness. The tip of the cantilever moved 150 mu m in the direction vertical to the substrate and 80 mu m in the horizontal direction; these were the maximum displacements obtained with 33 mW dissipated in the heater. The cut-off frequency was 10 Hz. On a 1-cm-square substrate, 512 cantilevers were fabricated to form an array. Two sets of cantilevers were placed opposing to each other. We operated them in coordination to mimic the motion and function of cilia and carried a small piece of a silicon wafer (2.4 mg) at 27-500 mu m/s with 4-mW input power to each actuator. >

Effect of the composition and thermal annealing on the transformation temperatures of sputtered TiNi shape memory alloy thin films

Abstract After sputter-deposited amorphous TiNi films were subjected to heat treatment higher than 600 K, the shape memory alloys (SMAs) showed strong dependence of the transformation temperatures on heat treatment conditions and composition. Unlike Ni-rich films, the transformation temperatures of Ti-rich films are above the ambient temperature and largely depend on annealing temperatures from 600 to 1200 K. But they remain relatively constant on the various annealing temperature domains, 600–740 K, 740–1000 K, 1000 K +, delimited by exothermic peaks originating from the formation of precipitates. The measurements by differential scanning calorimetry, performed on TiNi thin films annealed below 740 K, showed transformation temperatures appropriate for medical applications and very small transformation temperature hysteresis of 3 K, resulting in a beneficial effect of SMA cyclic microactuators. Furthermore, using these lower annealing temperatures reduces both thermal and mechanical stresses and makes possible the development of SMA micro-actuators on substrates, that are unstable at elevated temperatures, and on electronic devices.

A microactuator for head positioning system of hard disk drives

We proposed a new microactuator to realize high track density of Hard Disk Drives (HDDs). The proposed actuator is an electrostatic actuator with multiple parallel plate electrodes and it drives only a Read/Write (R/W) head element. The actuator is fabricated by micromachining technologies. We show the desired design parameters of actuators which will achieve 40 kilo track per inch (TPI). The required driving gap aspect ratio for a silicon actuator and a nickel actuator are 20 and 50 respectively. The aspect ratio of 20 for silicon will be realized by an Inductively Coupled Plasma (ICP) etching process and the aspect ratio of 50 for nickel will be fabricated by a novel electroforming process with vertical sacrificial layer.

An electrostatic micro actuator for a magnetic head tracking system of hard disk drives

We propose a new micro actuator to realize high track density of hard disk drives (HDDs). The proposed actuator is a bi-directional driving (BDD) electrostatic actuator with multiple parallel plate electrodes. The actuator generates a large force that is twice as much as the force of a conventional unidirectional driving (UDD) actuator, and it is fabricated by micro machining technologies. The driving theory is verified by experiments with a prototype. We demonstrate the capability of actuators which will achieve 40 k track per inch (TPI). The fabrication process of the actuators for 40 kTPI is under development.

Design, Fabrication, and Operation of Two-Dimensional Conveyance System With Ciliary Actuator Arrays

In this paper, we present the design, fabrication, and operation of a two-dimensional (2-D) microconveyance system. Conceptually, this system was designed as a mechanical part of an autonomous decentralized system composed of integrated micro actuator-sensor-controller cells. The presented system is a 2-D ciliary motion system (2-D CMS) composed of arrayed cantilever actuators. The actuators are made of two types of polyimide with different thermal expansion coefficients. They are thermally driven by flowing current in laminated heaters between the polyimide layers. We investigated the 2-D conveyance characteristics of the 2-D CMS consisting of 20times20 cells. Each cell has a pitch of 1420 mum consisting of four actuators of 500 mum in length. The conveyance was performed in a voltage range of 19-32 V, which corresponds to approximately 48-136 mW/cell, in a frequency range of 1-100 Hz, which corresponds to approximately 2-18 mum of minimum step size. We operated it in a feedback control scheme. In feedback operation mode, the 2-D CMS was controlled with a charge-coupled device (CCD) camera regulated by a PC and a programmable logic device (PLD). We succeeded to convey an object to a predetermined target point on the surface of the CMS.

Group work of distributed microactuators

This paper proposes and demonstrates a method to obtain macroscopic work out of distributed microactuators fabricated by IC-compatible micromachining processes. We have coordinated the simple and small motion of microactuators in order to perform a task. The concept and a control scheme are discussed first. In order to show the feasibility, the fabrication and operation of arrayed microactuators for conveyors are described. One uses thermally driven cantilevers and the other uses controlled air flow from micronozzles to carry flat objects.

Atomic Force Microscope Cantilever Array for Parallel Lithography of Quantum Devices

Arrayed atomic force microscope (AFM) cantilevers for parallel scanning probe lithography (SPL) have been fabricated by silicon micromachining. Fabrication is based on three KOH etching steps and local oxidation processes. The curvature radius of the tips is as sharp as 20 nm. A laser beam focused onto the middle probe enables us to observe the wafer for alignment and confirm the patterns after the SPL operation. Parallel SPL on N-octadecyltrimethoxysilane (ODS) self-assembled monolayer (SAM) films is susessfully demonstrated with five probes. Good alignment and homogeneity are obtained with simple operation. Parallel SPL for parallel quantum device fabrications is also reported.

SiO2 Electret Generated by Potassium Ions on a Comb-Drive Actuator

Silicon dioxide electret generated by doping potassium ions will be demonstrated by forming it on a comb-drive actuator. The comb-drive actuator made of silicon on an insulator substrate is oxidized with bubbling a stream of KOH solution to form silicon oxide film including potassium ions uniformly on the etched side walls of comb electrodes. After a bias-temperature procedure at about 900–1000 K and 100 V was applied to the device, we confirmed a 40 V built-in potential difference between the opposing comb electrodes. The gradual decay of the potential was observed, but 35 V was maintained even after 1 month.

Development of an X-ray imaging microcalorimeter with a pixel-type Ir transition edge sensor

Abstract We are developing an X-ray microcalorimeter with high energy resolution and position sensitivity by using an Iridium transition edge sensor. The Ir-TES with a new pixel-type geometry has ten small pixel TES array. Each pixel size is 80 μm ×200 μm . This device has shown a good energy resolution of 26 eV (FWHM) at 5.9 keV . Furthermore, the Ir-TES film was scanned along each pixel by a collimated X-ray microbeam and signal pulses were measured at each incident position. The pulse height and rise time map has shown ten different regions where pulses are concentrated which correspond to each pixel. This might be useful for an imaging TES array.

Frequency Transition Phenomenon of Self-Oscillated Micro-Cantilever by Changing Driving Voltage

We have found an interesting phenomenon of self-excited oscillation of electrostatic microcantilever; the device was found to be self-oscillated under an applied dc voltage, by repeating charge and discharge between the fixed and the movable electrodes. Oscillation frequency is changed by changing apply dc voltage. The phenomenon can be used to make a MEMS version of voltage-controlled oscillator (VCO) for constructing a simple voltage-controlled oscillator that is free from external inductors or capacitors.