Contact-less, Multi-Spectral Imaging of Dermal Perfusion
12 May 2008-pp 793-796
TL;DR: A variation of the accepted PPG technique is described, to provide a contact-less and non-invasive method of characterizing dermal perfusion, which employs a 3-CCD, multi-spectral camera, to image the selected area.
Abstract: Photoplethysmography (PPG) has come to be accepted as a common, non-invasive method for measuring the level of oxygen saturation in arterial blood. This paper describes a variation of the accepted PPG technique, to provide a contact-less and non-invasive method of characterizing dermal perfusion. It employs a 3-CCD, multi-spectral camera, to image the selected area. The acquired images are analysed by making use of the fact that the absorption co-efficient of oxygenated blood is more in the infra-red (IR) region of the spectrum, when compared to the red region. This fact is utilised to characterize the extent of dermal perfusion in the selected area of the skin.
Citations
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Patent•
07 Sep 2009
TL;DR: The invention relates to a system of PPG type of signal detection from a biological tissue, comprising a bearing zone to a portion of the tissue and means for forming a PPG signal from the array of receivers output signals.
Abstract: The invention relates to a system (1) of PPG type of signal detection from a biological tissue, comprising: a) a bearing zone (2 ') to a portion of the tissue, b) a die (2) nxm elementary optical receivers, and means for forming an output signal from each sensor, based on radiation received from a fabric bearing on the bearing region and a function of time, c) - means for forming a PPG signal from the array of receivers output signals.
Patent•
06 Sep 2010
TL;DR: In this paper, a system for detection of signaux du type PPG provenant d'un tissu biologique is presented. Butteau et al. porte sur un systeme (e.g., a zone de support) for a partie du tissu, a matrice, a set of nxm recepteurs optiques elementaires, and moyens de formation of a signal de sortie de chaque recepteur elementaire, en fonction du rayonnement qu'il recoit d'one tissu
Abstract: L'invention porte sur un systeme (1) de detection de signaux du type PPG provenant d'un tissu biologique, comprenant : a) une zone de support (2') pour une partie du tissu, b) une matrice (2) de nxm recepteurs optiques elementaires et des moyens de formation d'un signal de sortie de chaque recepteur elementaire, en fonction du rayonnement qu'il recoit d'un tissu reposant sur la zone de support et en fonction du temps, c) des moyens de formation d'un signal PPG a partir des signaux de sortie des recepteurs de la matrice.
Patent•
29 Sep 2010
TL;DR: In this article, a procede destine a faciliter l'obtention d'un premier signal (42, 50a-n) for analyse en vue de caracteriser au moins une composante periodique de celui-ci, consiste a obtenir a moins de two seconds signaux (18-20) representatifs des intensites du rayonnement electromagnetique capture, correspondant chacun a une plage de frequence de rayonnes differente respective.
Abstract: Un procede destine a faciliter l'obtention d'un premier signal (42; 50a-n) pour analyse en vue de caracteriser au moins une composante periodique de celui-ci, consiste a obtenir au moins deux seconds signaux (18-20) representatifs des intensites du rayonnement electromagnetique capture, correspondant chacun a une plage de frequence de rayonnement differente respective. Le premier signal (42; 50a-n) peut etre derive d'au moins un signal de sortie (31) qu'il est possible d'obtenir par application d'une transformation (22, 26, 30) aux seconds signaux (18-20; 55-57) de telle sorte que n'importe quelle valeur du signal de sortie (31) repose sur des valeurs obtenues a partir de chaque second signal respectif (18-20; 55-57) a des moments precis correspondants. Le procede consiste en outre a obtenir au moins une valeur d'au moins une variable qui determine les influences d'au moins des composantes des seconds signaux respectifs (18-20; 55-57) sur le signal de sortie (31) lorsque les signaux qui correspondent aux seconds signaux (18-20; 55-57) sont captures et la transformation (22, 26, 30) appliquee, au moins au moyen de : (i) analyse des seconds signaux (18-20; 55-57), et/ou d'un signal de sortie (31) obtenu par application de la transformation (22, 26, 30) aux seconds signaux (18-20) et/ou d'un premier signal (42; 50a-n) derive du signal de sortie (31) et utilisation de l'analyse de maniere a selectionner au moins une valeur d'au moins un parametre (54) qui correspond a une variable respective des variables; et/ou (ii) calcul des valeurs d'au moins un facteur qui varie dans le temps qui correspond a une variable respective des variables, chaque valeur de facteur reposant sur au moins une valeur de second signal, et application de chaque facteur dans une operation dans au moins une sequence d'un certain nombre de sequences d'operations paralleles qui comprennent au moins une telle operation, et consideration d'un signal correspondant a un signal respectif des seconds signaux (55-57) comme entree.
Patent•
29 Sep 2010
TL;DR: In this article, a method for obtaining a first signal (42, 50a-n) for analysis to characterize at least one periodic component thereof, including obtaining at least two second signals (18-20) representative of intensities of captured electromagnetic radiation, each corresponding to a respective different radiation frequency range.
Abstract: A method of facilitating obtaining a first signal (42; 50a-n) for analysis to characterize at least one periodic component thereof, includes obtaining at least two second signals (18-20) representative of intensities of captured electromagnetic radiation, each corresponding to a respective different radiation frequency range. The first signal (42; 50a-n) is at least derivable from an output signal (31) obtainable by applying a transformation (22,26,30) to the second signals (18-20; 55-57) such that any value of the output signal (31) is based on values from each respective second signal (18-20; 55-57) at corresponding points in time. The method further includes obtaining at least one value of at least one variable determining influences of at least components of respective second signals (18-20; 55-57) on the output signal (31) when the signals corresponding to the second signals (18-20; 55-57) are captured and the transformation (22,26,30) is applied, by at least one of: (i) analyzing at least one of the second signals (18-20; 55-57), an output signal (31) obtained by applying the transformation (22,26,30) to the second signals (18-20) and a first signal (42; 50a-n) derived from the output signal (31) and using the analysis to select at least one value of at least one parameter (54) corresponding to a respective one of the variables; and (ii) calculating values of at least one time- varying factor corresponding to a respective one of the variables, each factor value based on at least one second signal value, and applying each factor in an operation in at least one of a number of parallel sequences of operations comprising at least one such operation and taking a signal corresponding to a respective one of the second signals (55-57) as input.
Patent•
27 Jul 2012
References
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01 May 2007
TL;DR: In this article, a singular value decomposition (SVD) based method is proposed to reduce motion artifacts from corrupted PPG signals, which is shown to achieve stable and reliable SpO2 measurement even when PPGs are distorted by motion artifacts.
Abstract: Artifact free photoplethysmographic (PPG) signals, obtained with red and infrared (IR) optical sources and detectors are necessary for non-invasive estimation of oxygen saturation (SpO2) in arterial blood. Movement of a patient corrupts the PPGs with motion artifacts, resulting in large errors in the computation of SpO2. This paper presents a novel singular value decomposition (SVD) based method to reduce motion artifacts from corrupted PPG signals. Test results on a prototype incorporating the proposed SVD technique show that stable and reliable SpO2 measurement is achieved even when PPGs are distorted by motion artifacts, thus establishing the efficacy of the proposed method.
83 citations
"Contact-less, Multi-Spectral Imagin..." refers background in this paper
...Research has also been carried out to desensitize a PPG to patient-dependent parameters [2, 3]....
[...]
24 Apr 2006
TL;DR: The design and development of a virtual instrument for the measurement of haemodynamic parameters namely, pulse rate and oxygen saturation in arterial blood based on the popular photoplethysmographic (PPG) principle is presented.
Abstract: This paper presents the design and development of a virtual instrument for the measurement of haemo-dynamic parameters namely, pulse rate and oxygen saturation in arterial blood based on the popular photoplethysmographic (PPG) principle. A clip-on sensor, housing red and infrared (IR) light emitting diodes and suitable photo detectors is developed. The sensor is interfaced to a PC utilizing the audio channel of the sound card, thus dispensing with expensive analog to digital converter hardware. Since the frequency response of the audio channel is not suitable for the PPG waveforms of red and IR, FM modulation and demodulation are employed. An empirical relationship is developed for the computation of the oxygen saturation in arterial blood using the red and IR PPG data and the well-known and well-established extinction coefficients of haemoglobin with and without oxygen. Data acquisition and processing are accomplished under LabVIEW virtual environment.
27 citations
"Contact-less, Multi-Spectral Imagin..." refers background in this paper
...Recent advances in PPG technology have led to the development of a Virtual Instrument based Pulse Oximeter [1] and reliable and robust algorithms for artifact reduction....
[...]
16 Oct 2002
TL;DR: It is shown that reflectance measurements can be used to determine the amount of blood O/sub 2/ saturation of a wound, and an algorithm designed to calculate the blood oxygen saturation from narrow band reflectance images at 760 and 800 nm was used.
Abstract: Reflectance spectroscopy is a common technique used to analyze blood oxygen saturation in biological tissues. This study describes a non-invasive method for mapping blood oxygen saturation in wounds using reflectance measurements obtained from a hyperspectral imaging system. The maps illustrate changes in blood oxygen saturation with high spatial resolution. This allows observation into local blood oxygen supplies of tissue as opposed to common point measurement techniques such as pulse oximetry and optical fiber probing. To demonstrate this, an algorithm designed to calculate the blood oxygen saturation from narrow band reflectance images at 760 and 800 nm was used. The algorithm incorporates the contributions of absorption by oxy-(HbO/sub 2/) and deoxy-hemoglobin (Hb) at the oxygen (O/sub 2/) sensitive and O/sub 2/ insensitive wavelength. Results of the algorithms performance are presented to demonstrate that reflectance measurements can be used to determine the amount of blood O/sub 2/ saturation of a wound.
25 citations