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N. Yazdi

Bio: N. Yazdi is an academic researcher from University of Michigan. The author has contributed to research in topics: Capacitive sensing & Microsystem. The author has an hindex of 16, co-authored 29 publications receiving 2812 citations.

Papers
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Journal ArticleDOI
01 Dec 1998
TL;DR: Inertial sensors have seen a steady improvement in their performance, and today, microaccelerometers can resolve accelerations in the micro-g range, while the performance of gyroscopes has improved by a factor of 10/spl times/ every two years during the past eight years.
Abstract: This paper presents a review of silicon micromachined accelerometers and gyroscopes. Following a brief introduction to their operating principles and specifications, various device structures, fabrication, technologies, device designs, packaging, and interface electronics issues, along with the present status in the commercialization of micromachined inertial sensors, are discussed. Inertial sensors have seen a steady improvement in their performance, and today, microaccelerometers can resolve accelerations in the micro-g range, while the performance of gyroscopes has improved by a factor of 10/spl times/ every two years during the past eight years. This impressive drive to higher performance, lower cost, greater functionality, higher levels of integration, and higher volume will continue as new fabrication, circuit, and packaging techniques are developed to meet the ever increasing demand for inertial sensors.

1,816 citations

Journal ArticleDOI
TL;DR: A high-sensitivity low-noise capacitive accelerometer system with one micro-g//spl radic/Hz resolution and a detailed noise analysis of electromechanical sigma-delta capacitives with a final goal of achieving sub-/spl mu/g resolution is presented.
Abstract: This paper reports a high-sensitivity low-noise capacitive accelerometer system with one micro-g//spl radic/Hz resolution. The accelerometer and interface electronics together operate as a second-order electromechanical sigma-delta modulator. A detailed noise analysis of electromechanical sigma-delta capacitive accelerometers with a final goal of achieving sub-/spl mu/g resolution is also presented. The analysis and test results have shown that amplifier thermal and sensor charging reference voltage noises are dominant in open-loop mode of operation. For closed-loop mode of operation, mass-residual motion is the dominant noise source at low sampling frequencies. By increasing the sampling frequency, both open-loop and closed-loop overall noise can be reduced significantly. The interface circuit has more than 120 dB dynamic range and can resolve better than 10 aF. The complete module operates from a single 5-V supply and has a measured sensitivity of 960 mV/g with a noise floor of 1.08 /spl mu/g//spl radic/Hz in open-loop. This system can resolve better than 10 /spl mu/g//spl radic/Hz in closed-loop.

196 citations

Proceedings ArticleDOI
01 Jan 2004
TL;DR: In this article, a review of capacitive readout front-end circuits for high-precision accelerometers is presented, and the primary design parameters and the trade-offs affecting the resolution are presented.
Abstract: This paper presents a review of capacitive readout front-end circuits for high-precision accelerometers. The primary design parameters and the trade-offs affecting the resolution are presented. The discussions apply to all capacitive microsensor interfaces. Also, a high-sensitivity capacitive accelerometer interface circuit for hybrid-integration with a surface/bulk micromachined micro-g accelerometer is described. The first generation of the circuit resolves 75 aF of capacitance on /spl sim/120 pF parasitic capacitance with a 200 kHz sampling rate, and the second generation resolves 20 aF with 1 MHz sampling rate. The overall sensor-circuit module has a noise floor of 1.6 /spl mu/g//spl radic/Hz at ambient atmosphere.

142 citations

Journal ArticleDOI
01 Dec 1998
TL;DR: System features such as active power management, the intramodule sensor bus, generic bus interface circuitry, and in-module sensor compensation based on bivariate polynomials are discussed.
Abstract: An open-architecture microsystem that can be populated with a variety of sensors and actuators is described. The microsystem is designed for low-power wireless applications where small size and high sensor accuracy are important. It consists of an in-module microcontroller connected to multiple front-end transducers through an intramodule sensor bus. An external interface allows internally processed data to be output through either a hard-wired input/output port or a radio-frequency transmitter. The present microsystem is configured for environmental monitoring and measured temperature, barometric pressure, relative humidity, and acceleration/vibration. It occupies less than 10 cc, consumes an average of 530 /spl mu/W from 6 V, and transmits data up to 50 m. System features such as active power management, the intramodule sensor bus, generic bus interface circuitry, and in-module sensor compensation based on bivariate polynomials are discussed.

113 citations

Journal ArticleDOI
TL;DR: In this article, a low-power sensor interface chip compatible with smart microsystems and a wide range of capacitive transducers is presented, which can communicate with an external microcontroller using a nine-line sensor bus standard, contains a switched-capacitor readout circuit, and includes a temperature sensor.
Abstract: This paper presents a generic low-power sensor interface chip compatible with smart microsystems and a wide range of capacitive transducers. The interface chip is highly programmable, can communicate with an external microcontroller using a nine-line sensor bus standard, contains a switched-capacitor readout circuit, supports sensor self-test, and includes a temperature sensor. The circuit can interface with up to six external sensors and contains three internal programmable reference capacitors in the range of 0.15–8 pF. The chip measures 3.2×3.2 mm in a standard 3-μm single-metal double-poly p-well process, dissipates less than 2.2 mW from a single 5 V supply, and can resolve input capacitance variations of less than 1 fF in 10 Hz bandwidth.

79 citations


Cited by
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Journal ArticleDOI
07 Apr 2000-Science
TL;DR: An extension to the soft lithography paradigm, multilayersoft lithography, with which devices consisting of multiple layers may be fabricated from soft materials is described, to build active microfluidic systems containing on-off valves, switching valves, and pumps entirely out of elastomer.
Abstract: Soft lithography is an alternative to silicon-based micromachining that uses replica molding of nontraditional elastomeric materials to fabricate stamps and microfluidic channels. We describe here an extension to the soft lithography paradigm, multilayer soft lithography, with which devices consisting of multiple layers may be fabricated from soft materials. We used this technique to build active microfluidic systems containing on-off valves, switching valves, and pumps entirely out of elastomer. The softness of these materials allows the device areas to be reduced by more than two orders of magnitude compared with silicon-based devices. The other advantages of soft lithography, such as rapid prototyping, ease of fabrication, and biocompatibility, are retained.

4,218 citations

PatentDOI
24 Sep 2003-Science
TL;DR: The fluidic multiplexor as discussed by the authors is a combinatorial array of binary valve patterns that exponentially increases the processing power of a network by allowing complex fluid manipulations with a minimal number of inputs.
Abstract: High-density microfluidic chips contain plumbing networks with thousands of micromechanical valves and hundreds of individually addressable chambers. These fluidic devices are analogous to electronic integrated circuits fabricated using large scale integration (LSI). A component of these networks is the fluidic multiplexor, which is a combinatorial array of binary valve patterns that exponentially increases the processing power of a network by allowing complex fluid manipulations with a minimal number of inputs. These integrated microfluidic networks can be used to construct a variety of highly complex microfluidic devices, for example the microfluidic analog of a comparator array, and a microfluidic memory storage device resembling electronic random access memories.

2,292 citations

Journal ArticleDOI
01 Dec 1998
TL;DR: Inertial sensors have seen a steady improvement in their performance, and today, microaccelerometers can resolve accelerations in the micro-g range, while the performance of gyroscopes has improved by a factor of 10/spl times/ every two years during the past eight years.
Abstract: This paper presents a review of silicon micromachined accelerometers and gyroscopes. Following a brief introduction to their operating principles and specifications, various device structures, fabrication, technologies, device designs, packaging, and interface electronics issues, along with the present status in the commercialization of micromachined inertial sensors, are discussed. Inertial sensors have seen a steady improvement in their performance, and today, microaccelerometers can resolve accelerations in the micro-g range, while the performance of gyroscopes has improved by a factor of 10/spl times/ every two years during the past eight years. This impressive drive to higher performance, lower cost, greater functionality, higher levels of integration, and higher volume will continue as new fabrication, circuit, and packaging techniques are developed to meet the ever increasing demand for inertial sensors.

1,816 citations

01 Jan 2004
TL;DR: An overview of this new and exciting field of wireless sensor networks is provided and a brief discussion on the factors pushing the recent flurry of sensor network related research and commercial undertakings is discussed.
Abstract: Sensor networks consist of a set of sensor nodes, each equipped with one or more sensors, communication subsystems, storage and processing resources, and in some cases actuators. The sensors in a node observe phenomena such as thermal, optic, acoustic, seismic, and acceleration events, while the processing and other components analyze the raw data and formulate answers to specific user requests. Recent advances in technology have paved the way for the design and implementation of new generations of sensor network nodes, packaged in very small and inexpensive form factors with sophisticated computation and wireless communication abilities. Although still at infancy, these new classes of sensor networks, generally referred to as wireless sensor networks (WSN), show great promise and potential with applications ranging in areas that have already been addressed, to domains never before imagined. In this article we provide an overview of this new and exciting field and a brief discussion on the factors pushing the recent flurry of sensor network related research and commercial undertakings. We also provide overview discussions on architectural design characteristics of such networks including physical components, software layers, and higher level services. At each step, we highlight special characteristics of WSNs and discuss why existing approaches and results from wireless communication networks are not necessarily suitable in WSN domains. We conclude by briefly summarizing the state of the art and the future research directions.

1,740 citations

Patent
01 Feb 1999
TL;DR: An adaptive interface for a programmable system, for predicting a desired user function, based on user history, as well as machine internal status and context, is presented for confirmation by the user, and the predictive mechanism is updated based on this feedback as mentioned in this paper.
Abstract: An adaptive interface for a programmable system, for predicting a desired user function, based on user history, as well as machine internal status and context. The apparatus receives an input from the user and other data. A predicted input is presented for confirmation by the user, and the predictive mechanism is updated based on this feedback. Also provided is a pattern recognition system for a multimedia device, wherein a user input is matched to a video stream on a conceptual basis, allowing inexact programming of a multimedia device. The system analyzes a data stream for correspondence with a data pattern for processing and storage. The data stream is subjected to adaptive pattern recognition to extract features of interest to provide a highly compressed representation that may be efficiently processed to determine correspondence. Applications of the interface and system include a video cassette recorder (VCR), medical device, vehicle control system, audio device, environmental control system, securities trading terminal, and smart house. The system optionally includes an actuator for effecting the environment of operation, allowing closed-loop feedback operation and automated learning.

1,182 citations