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Shiraishi N.,NMEMS Technology Research Organization | Shiraishi N.,Tokyo University of Agriculture and Technology | Kimura M.,NMEMS Technology Research Organization | Kimura M.,Shinshu University | And 2 more authors.
Microelectronic Engineering | Year: 2014

We have developed and evaluated a PMMA-based gas sensor to realize a low-cost sensor network system for monitoring VOCs (volatile organic compounds). The PMMA-based gas sensor consists of a PMMA (poly methyl methacrylate) cantilever, a piezoelectric film of PVDF (polyvinylidene fluoride), and a thin film of PBD (polybutadiene). We began by investigating the influence of PBD coating of a dynamic property of the PMMA cantilever in a higher order resonance mode under atmospheric pressure at room temperature. The PBD-coated PMMA cantilever had a resonant frequency of 341 kHz and quality factor of 71 at the 4th flexural vibration mode. Next, we examined the change of resonance frequency in the presence of toluene vapor by setting up a gas sensor evaluation system equipped with a VOC dilution flow system, temperature-controlled chamber, oscillation circuit, and frequency counter. The resonant frequency shifted when the PMMA-based gas sensor was exposed to toluene vapor. The measured toluene sensitivity in the experiment was 0.02 Hz/ppm. © 2014 Elsevier B.V. All rights reserved.

Morikawa Y.,ULVAC Inc. | Morikawa Y.,NMEMS Technology Research Organization | Sakuishi T.,ULVAC Inc. | Sakuishi T.,NMEMS Technology Research Organization | Suu K.,ULVAC Inc.
46th International Symposium on Microelectronics, IMAPS 2013 | Year: 2013

"2.5D silicon interposers" and "Hetero 3D stacked" technology for high-performance LSI are gathering the most attention from now on. These technologies can solve interconnection problems using TSV (Through Silicon Via) to electrically connect stacked each function devises. 2.5D and hetero-3D Si integration has great advantages over conventional 2D devices such as high packaging density, small wire length, high-speed operation, low power consumption, and high feasibility for parallel processing. But, the radical problem about the TSV production cost is not still solved. In particular, the demand to a new plating bath technology to shorten Cu plating time is expected. On the other hand, TSV isolation liner materials with lower cost for high frequency devices will be necessary in the future. "Scallop-free" etching process has developed for TSV fabrication [1]. As a result, the smooth-sidewall had proved shorten PVD process time [2]. At first, it investigated a cost correlation of taper-shape etching and Cu-ECP (electro-chemical plating) in this paper. And then, a polyurea film using a vapor deposition polymerization technology (which is Ulvac's FPF/PV large panel technology) tried introduction as isolation liner for next-generation high frequency device. And, it performed the film formation to a TSV pattern.

Tomimatsu Y.,NMEMS Technology Research Organization | Takahashi H.,University of Tokyo | Kobayashi T.,Japan National Institute of Advanced Industrial Science and Technology | Matsumoto K.,University of Tokyo | And 3 more authors.
Proceedings of the 2013 IEEE 8th International Conference on Intelligent Sensors, Sensor Networks and Information Processing: Sensing the Future, ISSNIP 2013 | Year: 2013

This paper reports a wake-up switch using a piezoelectric differential pressure sensor in order to reduce the power consumption of a wireless sensor node. Air pressure change surrounding the sensor is detected by using a Pb(Zr, Ti)O3(PZT) thin film cantilever with the dimension of 1500 μm × 1000 μm × 2 μm. The sensor has high sensitivity with low power consumption due to its thin cantilever and low capacitance. The sensitivity was 2.4 mV/Pa from -30 Pa to 30 Pa. It was demonstrated that the fabricated sensor performed as a wake-up switch when pressure varies in 10 Pa with low power consumption. © 2013 IEEE.

Lu J.,Japan National Institute of Advanced Industrial Science and Technology | Okada H.,Japan National Institute of Advanced Industrial Science and Technology | Itoh T.,Japan National Institute of Advanced Industrial Science and Technology | Harada T.,NMEMS Technology Research Organization | Maeda R.,Japan National Institute of Advanced Industrial Science and Technology
IEEE Sensors Journal | Year: 2014

Pursuit of the lowest size-limit of wireless sensor nodes may not only reduce power consumption and production cost, but also enables its layout-free ubiquitous applications, i.e., in our green sensor networks to compress energy consumption through visibility and optimization. In this paper, we engaged in developing the world smallest wireless sensor node with ultralow power consumption from both electrical block integration and physical interconnection points-of-view. A customized IC for signal processing and data transmission, which has universal interface to sensors and power management capability, was designed and then fabricated by using 0.18 μm 1.8 V/3.3 V 1P6M logic process. By introducing buried bump interconnection technology, we have successfully obtained one of the world's smallest wireless sensor nodes, as small as 3.9 mm × 3.9 mm × 3.5 mm, for humidity and temperature monitoring. The sensor node also features an general purpose interface, available for analog and digital sensors, and the ultrasmall footprint of above sensor node enables its layout-free distribution or integration inside other remote sensing systems. Although the adopted antenna size was 2 cm × 5 cm, its flexibility enables free attach to any curved surfaces. Experimental results demonstrated that besides preferred ultralow power consumption and data transmission distance, configuration of above sensor nodes enables its easy assembly with stand-alone power source and flexible antenna for wide variety of applications. © 2001-2012 IEEE.

Tanaka J.,NMEMS Technology Research Organization | Imamoto H.,NMEMS Technology Research Organization | Seki T.,Omron Corporation | Oba M.,Omron Corporation
Proceedings of IEEE Sensors | Year: 2014

This paper describes the low power consumption wireless human detector which can monitor wide area. We have developed the S-shaped thermopile infrared sensor element by utilizing micro-electro-mechanical-systems (MEMS) technology. The developed thermopile infrared array sensor achieved high temperature resolution and fast response time. Number of human who exists in the detection area is simply detected by the human detection process using temperature outputs from the thermopile infrared array sensor. © 2014 IEEE.

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