Miniaturized Wireless Sensing System for Real-Time Breath Activity Recording
ABSTRACT A portable, non-invasive and easy to operate wireless system has been developed for monitoring the breathing activity of patient. The system is composed of a capacitive microsensor (airflow-humidity sensor) integrated on a silicon chip and of a Negative Temperature Coefficient thermistor; both are connected to a wireless network to allow efficient healthcare at home as well as in hospitals. The capacitive sensitive part of the microsensor is an array of interdigitated metallic electrodes covered by 100-nm-thick dense anodized aluminum oxide layer. The breath water vapor is adsorbed over the interdigitated electrodes and changes the sensor characteristic capacitance by up to two orders of magnitude. This modulated signal is then digitized and either stored in a memory or directly transmitted to a monitor through a short distance radio frequency (RF) link. Results show that the wireless platform can be powered by two AAA batteries and deployed in a mesh or star configuration as wireless sensor network. Full size of the microsensor is less than 1 cm2 and is conveniently implemented in a classical adhesive bandage or in nasal prongs. This microsystem is proposed for monitoring sleep-disordered breathing as well as breathing rhythm of athletes during effort.
Conference Proceeding: Training of line echo canceller with PRBS signals[show abstract] [hide abstract]
ABSTRACT: The paper addresses the problem of convergence time reduction for the line echo cancellation problem in the context of VoIP applications. Training signals can be used for this purpose. Intuitively speaking, any decorrelated signal, such as white noise, can be used as a training signal. C. Antweiler and H.-G. Symanzik (see Proc. ICASSP-1995, p.3031-4, 1995) have shown that a certain signal, called perfect sequence, can be such a training signal. The method for generating such signals is not easy to use, neither can it be extended to arbitrary lengths. The authors propose another candidate signal, called maximum length pseudo random binary sequence (mlPRBS), to be a perfect sequence. The conditions on such a signal are further analyzed and highlighted. It is shown that the proposed training signal fulfils such requirements. The claims are backed by simulation results. The simulation elements used are available in the public domain.Networking and Communication Conference, 2004. INCC 2004. International; 07/2004
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ABSTRACT: This paper presents an ultra low power pulse generator based on special design of a voltage controlled ring oscillator (VCRO). This pulse generator can be used as a capacitive sensor interface for MEMS applications with the advantage of using short pulse width to achieve lower power consumption and high sensitivity for low capacitance. The pulse frequency can be controlled by voltage bias. The design is made using 2 mum MEMS compatible silicon-on-insulator CMOS technology. The power consumption is estimated to be in the range of 2 muW when the pulse frequency is set to 300 kHz.01/2009;
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ABSTRACT: In-home healthcare and smart nursing are highly promoted recently by progress and advances in micro electromechanical systems (MEMS) and wireless sensor network (WSN) technology. In this work, a piezoelectric lead zirconate titanate (PZT) thin film actuated and sensed single crystal silicon disk resonator with excellent system integration capability, low driving voltage and great mechanical quality factor (Q-factor) was successfully developed for trace amount of chemicals detection as well as for recognition of gas molecular from human breath. The Q-factor dependence on geometries of the disk and the PZT pattern was investigated and discussed both in air and under reduced pressure. The equivalent capacitance and resistance of the PZT film at resonant frequency were measured. Applications in on-chip human healthcare are expected after system integration with CMOS and other MEMS components.