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Myocardial blood flow (MBF) measurement is possible using stationary cardiac SPECT cameras. Limited spatial resolution and blood vessels in the myocardium produce mixing of the blood and myocardial time-activity curves used for kinetic analysis. Our purpose was to evaluate the effect of correction for both spillover into the myocardium from blood and into the blood from myocardium on the accuracy of SPECT MBF estimation. Images from 31 patients who had dynamic one-day rest-stress myocardial SPECT studies using 99mTc-tetrofosmin were retrospectively processed both with attenuation correction (AC) and without (NC), and using a single spillover correction (SSO = blood to myocardium) and a dual spillover correction (DSO). Kl values from kinetic analysis with a 1-tissue compartment model were fit to a Renkin-Crone extraction fraction model (EF=1-exp(-α-β/MBF)) using 50 repeats of 2-fold cross validation to determine the method-specific K1-to-MBFconversion function. True MBF was measured using the clinical standard of PET imaging, with either 82Rb or 13N-ammonia, in the same patients. The model fit of SPECT K1 to PET MBF was not improved with dual spillover correction. With SSO, the Renkin-Crone model parameters were α=0.140, β =0.282 (AC, R2=0.71) and α = 0.187, β = 0.400 (NC, R2=0.75). With DSO, the parameters were α = 0.110, β = 0.265 (AC, R2=0.63) and α = 0.161, β = 0.352 (NC, R2=0.67). The limits of greement for the global relative MBF difference (SPECT – PET MBF/mean) were similar for DSO and SSO, both with AC ([-0.74 – 0.77] vs [-0.62– 0.64]) and without ([-0.67 – 0.71] vs [-.55 – 0.59]). Dual spillover correction alters the K1-to-MBF conversion function but does not improve the accuracy or precision of SPECT MBF measurements.

This paper addresses the issue of the mechanical reliability of MEMS piezoelectric vibration harvesters aimed at powering tire pressure monitoring systems. These harvesters generate sufficient power for the targeted application. However, for bringing them to the automotive market, their mechanical reliability has to be optimized, particularly in terms of shock resilience. Experimentally verified methods for improving the mechanical reliability of such devices are showcased in this article. These methods concern both the design of the harvesters (introduction of stoppers in the package) and their manufacturing process (release method of the MEMS structure).

Micro-system technology has enabled the development of energy harvesting at the micro-scale. However, in their approximate 15 years of existence, they have generated more attention than power. One of the reasons is the hype that is linked to this technology, leading to common misconceptions. After discussing these, we will present real facts and figures of micro-scale energy harvesting and some of the envisioned applications. We will focus on autonomous TPMS (tire pressure monitoring systems), enabled by vibration energy harvesting. We will discuss Electrostatic and Piezoelectric Energy Harvesters, and present some of the issues related to their fabrication and implementation. In case of a successful introduction, this application will pave the road to a whole range of devices powered by energy harvesting.

This paper presents the design, fabrication and characterization of a MEMS vibration energy harvester for tire pressure monitoring applications (TPMS). It is based on a SiO2-Si3N4 electret compatible with CMOS processing, thus allowing low cost production for large volumes. The device has a footprint of about 1 cm2. When excited by a sinusoidal vibration, the device generates a maximum AC power of 160 μW. This is one of the highest reported values for MEMS fabricated vibration energy harvester based on an electrostatic transduction mechanism. When excited by a vibration with characteristics similar to that measured in a tire, the maximum raw power is between 10 and 50 μW, which is sufficient to power a simple TPMS module. Furthermore, in contrast to most of electrostatic harvesters, our device exhibits a linear electromechanical behavior, due to its particular design. This simplifies greatly the modeling, optimization and experimental characterization of the device.

In this work we report shock induced measurement and simulations on AlN based piezoelectric vibration energy harvesters. We compare the result with sinusoidal input vibrations, where we obtain a record power of 489 µW. The vacuum packaged harvesters have high quality factors and high sensitivity. We validate the potential of piezoelectric vibration harvesters for car tire applications by measurements and simulations.

This paper describes the experimental characterization of piezoelectric harvesters with different dimensions. We present a record level of generated power of 85 µW obtained from an unpacked device. We have developed a wafer-scale vacuum package which shows a 100–200 fold increase in power output compared with packaged devices under atmospheric pressure. A wireless sensor node was fully powered by a piezoelectric harvester. The average power consumption was less than 10 µW while it was operating at 15 seconds duty cycle.

Vibration energy harvesters are an attractive option for powering low consumption wireless applications. Piezoelectric inertial devices based on a resonant behaviour are adapted to this type of applications for frequencies of the mechanical input in the range of hundreds of Hertz. However, in the case of human body applications, frequencies of a few Hertz are observed. For this reason, we developed an alternative approach based on the impact of a missile on piezoelectric beams. A model of such a harvester is first presented. Then, a prototype is experimentally characterized: 600µW were obtained for a 10Hz frequency and 10cm amplitude linear motion.

Current PET instrumentation and performance metrics have been developed primarily to optimize whole-body imaging with 18FDG. Dynamic 3D-mode PET imaging for quantification of myocardial blood flow (MBF) with 82Rb requires high count-rate capability and correction accuracy maintained over a wide range of activity. Therefore, we propose a new method to evaluate dynamic range for 3D cardiac PET imaging and evaluate the performance of a high count-rate PET system (GEHC Discovery Rx) for single-scan simultaneous quantification of MBF and left ventricular ejection fraction (EF) using list-mode PET imaging. Dynamic imaging was performed over a wide range of activities using 82Rb and 13NH 3 in a heart phantom, within and without an anthropomorphic torso, by FORE-FBP and a 12 mm 3D Hann filter. Time-activity curves (TAC) in the liver, myocardium and ventricle were analyzed to determine the operating range where quantitative accuracy is maintained in the reconstructed images. Dynamic rest-stress list-mode imaging was also performed in 21 patients with 82Rb PET to compare MBF and EF quantification between 2D and 3D-modes. Based on the phantom results, injected activity was targeted at 10 MBq/kg to permit accurate measurement of the bolus first-pass activity in the LV cavity. The phantom studies indicated that activity concentrations were measured accurately (≪15% deviation) with prompt count rates ≪10 Mcps and dead-time losses ≪35%. There was no count-rate-dependent loss of resolution observed in the myocardium:liver TACs, even above these limits. Residual scatter in the ventricle cavity:liver was 3.4% and consistent across the whole dynamic range. For the patient studies, pseudo-NEC rates were 30% higher in 3D (p≪0.001), resulting in improved image quality. There were no significant differences in segmental myocardium uptake distribution, LVEF or MBF between 2D and 3D-modes (P=NS). Conclusion: Quantitative 3D cardiac imaging appears to be accurate with 82Rb activity administered in the range of 9±1.5 MBq/kg used in this study. If the dynamic range of the PET system was increased further, higher injected activity and improved ECG-gated image quality may be obtained, while still retaining the quantitative accuracy of the first-pass data for accurate MBF quantification.

We demonstrate single-chip analog sensor-conditioning with integrated electrically-adjustable passive resistors, allowing adjustment by the sensor-system assembler, without the drawbacks of digital conditioning. Adding a rudimentary bulk-silicon cavity-etch to a standard 1mum CMOS process enables a group of innovations for thermally-isolated adjustable resistors, called RejustorsTM.

Piezoelectric converters designed for harvesting energy from mechanical vibrations have been fabricated by micromachining technologies. The manufactured piezoelectric energy harvesters have been characterized by applying a sinusoidal oscillation as mechanical input and by using a simple resistive load to measure the output power of the system. A maximum output power of 40 muW has been measured for an input vibration having a frequency of 1.8 kHz and an amplitude of 180 nm. A model aimed at estimating the output power of the fabricated piezoelectric structures has been developed and theoretical estimations have been compared with experimental results.

The INTEGRAL satellite was launched on October 17, 2002. All on-board instruments are operating successfully. In this paper, we focus on radiation effects on the Cadmium Telluride camera ISGRI. The spectral response of the camera is affected by cosmic particles depositing huge amount of energy, greater than the high threshold of the electronics. Our study raises the contribution of cosmic ray protons. Solutions are proposed to limit the degradation of spectral response of large pixel gamma cameras operating in space. We also address the effects of trapped electrons on the detector stability.

The present work concerns the concept and the modeling of a device for transforming a part of the mechanical energy originating from human limb motion into electrical energy. The device is formed by a frame containing a free moving mass. Useful electrical power is generated by the impact of this mass on piezoelectric cantilevers positioned at the end of the frame. In order to evaluate device performances a detailed analysis of the dynamics of the system is coupled to a model of the piezoelectric transducer. It is found that an optimized device, when mounted on the human wrist, can theoretically generate up to 40 /spl mu/W/cm/sup 3/.

A novel three state frequency detector (FD) is proposed and analysed. It complements a linear phase detector (PD). The parallel combination of these two detectors gives a new Phase-frequency detector (PFD), in which the frequency detection turns off when the phase difference is below 180 degrees. Thus, mismatches in the FD cannot affect the phase accuracy. This feature allows the designer to create a high-speed, no dead-zone wide capture range PLL, with low noise generation or sensitivity, and low power consumption. The enhanced linear PD has a higher gain at /spl plusmn/180 degrees and a better transfer function at high frequency than previous proposals. Those advantages give a better behaviour nearby /spl plusmn/180 degrees or at high frequencies, when the PD is used with the FD, in PLLs, or without the FD, like in Delay Locked Loops (DLL). It can detect phase differences between various signals selected from a broad class of waveform types. Results presented in this paper show that the proposed PD can cover a wide range of frequencies that easily reaches up to 4 GHz when implemented with TSMC 0.18 micron CMOS. The detector remains accurate and linear up to the highest experimented frequencies. Thus, it can be useful for precise analog clock skew measurements. Its simple topology uses only 24 MOS transistors that can be mostly of minimum size.

A new phase detector is proposed and analyzed. Its linear differential structure leads to significant advantages such as the absence of a dead zone, an insensitivity to common mode noise on input signals, a low switching activity that reduces noise and power dissipation, and finally, a good acquisition behaviour. The proposed detector can detect phase differences between various signals selected from a broad class of clock signal waveform types. Moreover it has a very low phase offset, in spite of process variations. Results presented in this paper show that the proposed detector can cover a wide range of frequencies that reaches up to 2 GHz when implemented with TSMC 0.35 micron CMOS. The detector remains accurate up to the highest experimental frequencies. Its simple topology uses only 26 MOS transistors, most of which can be of minimum size.

This paper deals with the problem of finding the time-optimal motion along a predefined path that satisfies the non-holonomic rolling without slipping constraint for a class of wheeled mobile robots described by their dynamical model. Admissible paths are first described. Then, an algorithm is proposed that gives the optimal motion.

We have evidenced co- and counter-propagating dark pulses in the laser mode of gain clamped semiconductor optical amplifiers (GCSOA)s perturbed by an intense ultrafast pulse. They decay into a long-lived two mode beating. The resulting gain modulation may be a limiting factor for applications.

This paper gives an overview of the results of SOA and clamped gain SOA gate arrays operating at 1.55 /spl mu/m as well as their performances in routing and switching applications and their potential for large-scale space switches.

All-optical 2R regeneration in an SOA-based Mach-Zehnder interferometer is demonstrated at 40 Gbit/s. The regenerative capabilities combined with an input power dynamic range of 16 dB demonstrate the feasibility of this technique at very high bit rates.

All-optical 2R regeneration, with wavelength conversion, at 40 Gbit/s is demonstrated in an all-active Mach-Zehnder interferometer showing the capability of improving the signal-to-noise ratio by more than 20 dB.