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Zürich, Switzerland

Daneshgar S.,Tyndall National Institute | De Feo O.,Solianis Monitoring AG | Kennedy M.P.,Tyndall National Institute
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2011

An intuitive approach to analyze the behavior of an LC Injection-Locked Frequency Divider was presented in Part I of this work; that paper provided insight into the locking behavior in the valid design area of the circuit. In this paper, we present a rigorous design methodology which provides a closed form equation showing where the locking range is wider. Theoretical predictions of the locked regions are verified by simulations of the circuit in Spectre RF using 0.35-μm CMOS technology models. © 2010 IEEE. Source

Daneshgar S.,University College Cork | Daneshgar S.,Tyndall National Institute | De Feo O.,Solianis Monitoring AG | Kennedy M.P.,University College Cork | Kennedy M.P.,Tyndall National Institute
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2010

The use of resonant injection-locked frequency dividers in frequency synthesizers has increased in recent years due to their lower power consumption compared to conventional digital prescalers. Numerous circuit ideas have been proposed, but there are few and sometimes contradictory estimates of the locking ranges (LRs) in these dividers. Despite several attempts, there is still no accurate analytical method to predict the LR. In this paper, we present a nonlinear approach based on the application of bifurcation theory to predict where the LR is wider rather than to say precisely how wide it is. The results presented have been derived by numerical bifurcation analysis using AUTO and have been verified by circuit simulations and experiments. In Part II, we will show how the insights developed in this paper lead to a rigorous design methodology. © 2010 IEEE. Source

Skipetrov S.E.,CNRS Physics and Models in Condensed Media Laboratory | Peuser J.,University of Fribourg | Cerbino R.,University of Fribourg | Cerbino R.,University of Milan | And 3 more authors.
Optics Express | Year: 2010

We study the noise of the intensity variance and of the intensity correlation and structure functions measured in light scattering from a random medium in the case when these quantities are obtained by averaging over a finite number N of pixels of a digital camera. We show that the noise scales as 1/N in all cases and that it is sensitive to correlations of signals corresponding to adjacent pixels as well as to the effective time averaging (due to the finite integration time) and spatial averaging (due to the finite pixel size). Our results provide a guide to estimation of noise levels in such applications as multi-speckle dynamic light scattering, time-resolved correlation spectroscopy, speckle visibility spectroscopy, laser speckle imaging etc. © 2010 Optical Society of America. Source

Caduff A.,Solianis Monitoring AG | Talary M.S.,Solianis Monitoring AG | Zakharov P.,Solianis Monitoring AG
Diabetes Technology and Therapeutics | Year: 2010

It is widely accepted that noninvasive glucose monitoring (NIGM) has the potential to revolutionize diabetes therapy. However, current approaches to NIGM studied to date have not yet demonstrated a level of acceptable functionality to allow real-time use, beyond restricted fields of application. A number of reviews have been devoted to the subject of NIGM with different focuses related to challenges and a description of the respective underlying problems. This review is aimed at addressing a fundamental topic in the application of NIGM that seems to have received less attention, by describing the perturbations that result in a reduced functionality of NIGM in daily use. Here we provide a short general introduction to glucose monitoring and a basic illustration of the electromagnetic spectrum with a description of the respective physical mechanisms underlying the measurement techniques. This allows for a better understanding of how these perturbing factors affect the measured properties. Cutaneous blood perfusion is one of the major perturbing factors to NIGM, along with variations in temperature, migration of water, and the effect of attachment of the sensor to the skin. An understanding of the mechanisms underlying perfusion variation over time and within the measured human skin tissue matrix is required to enable a discrimination between glucose-induced effects within the tissue and various biophysical impacts to be made. It is suggested that a plurality of probing frequencies is required to discriminate glucose-related changes from the perturbations. A system designed to perform the measurements in different regions of the electromagnetic spectrum with dedicated sensors (multisensor approach) has the potential to more efficiently and reliably discriminate glucose-related information from perturbations. This can be achieved by combining signals related to measurements with different physical underlying mechanisms of the interaction between the probing field propagation and the tissue to help account for the different sources of perturbations. Copyright 2010, Mary Ann Liebert, Inc. Source

Zakharov P.,Solianis Monitoring AG | Talary M.S.,Solianis Monitoring AG | Kolm I.,University of Zurich | Caduff A.,Solianis Monitoring AG
Physiological Measurement | Year: 2010

Changes in morphology of the skin are an important factor that can affect non-invasive measurements performed through this organ, in particular for glucose monitoring in e.g. patients with diabetes mellitus. A characterization technique for non-contact in vivo profiling of the superficial skin layers can be beneficial for evaluation of the performance of such measurement systems. We applied a full-field optical coherence tomography (OCT) system followed by the fully automatic processing for this task. With the developed procedure, non-invasive quantification of the skin morphology can be performed within a few minutes. The dorsal skin of the upper arm of 22 patients with Type 1 Diabetes Mellitus was investigated with an OCT system and with a commercially available dermatological laser scanning confocal microscope (CM) as a reference method. The estimates of epidermal thickness from OCT were compared with the results of expert-assisted analysis of confocal images. The highest correlation with the CM measurements has been obtained for the distance from the entrance peak to the first minimum of the OCT reflection profile (). In this specific patient group, we have observed a statistically significant correlation of the subjects' body mass index with the distance from the entrance peak to the dermal reflection peak in the OCT profile (p = 0.010). Furthermore, the same OCT parameter is negatively correlated with age with marginal statistical significance (p = 0.062). At the same time, no relation of diabetes-related parameters (duration of disease and concentration of glycated haemoglobin) to the skin morphology observed with the OCT and CM was found. © 2010 Institute of Physics and Engineering in Medicine. Source

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