ABSTRACT In order to measure muscle physiological parameters such as pH and oxygen partial pressu... more ABSTRACT In order to measure muscle physiological parameters such as pH and oxygen partial pressure (PO2) by continuous wave (CW) diffuse reflectance near-infrared spectroscopy (NIRS), light must penetrate through skin and subcutaneous fat layers overlying muscle. In this study, the effect of skin and subcutaneous fat layer and on the spatial sensitivity profile of CW diffuse reflectance near-infrared spectra is investigated through Monte Carlo simulations. The simulation model uses a semi-infinite medium consisting of skin, fat and muscle. The optical properties of each layer are taken from the reported optical data at 750 nm. The skin color is either Caucasian or Negroid and the fat thickness is varied from 0 ~ 20 mm. The spatial sensitivity profile, penetration depth, and sensitivity ratio as functions of optical fiber source-detector separation (SD, 2.5 mm, 5.0 mm, 10.0 mm, 20.0 mm, 30.0 mm and 40.0 mm), skin color and fat thicknesses are predicted by the simulations. It is shown that skin color only slightly influenced the spatial sensitivity profile, while the presence of the fat layer greatly decreased the detector sensitivity. It is also shown that probes with longer SD separations can detect light from deeper inside the medium. The simulation results are used to design a fiber optic probe which ensures that enough light is propagated inside the muscle in NIRS measurement on a leg with a fat layer of normal thickness.
Smart Medical and Biomedical Sensor Technology IV, 2006
It is estimated that 750,000 cases of severe sepsis occur in the United States annually, at least... more It is estimated that 750,000 cases of severe sepsis occur in the United States annually, at least 225,000 of which are fatal, resulting in significant utilization of healthcare resources and expenses. Significant progress in the understanding of pathophysiology and treatment of ...
We have previously demonstrated the correlation of continuous-wave near infrared (CW-NIR) tissue ... more We have previously demonstrated the correlation of continuous-wave near infrared (CW-NIR) tissue measurements, to blood and tissue metabolic parameters using Partial Least Squares (PLS) regression. The practical use of this non-invasive measurement technique ...
ABSTRACT Multivariate Optical Computing (MOC) devices have the potential of greatly simplifying a... more ABSTRACT Multivariate Optical Computing (MOC) devices have the potential of greatly simplifying as well as reducing the cost of applying the mathematics of multivariate regression to problems of chemical analysis in the real world. These devices utilize ...
The application of multivariate calibration models, specifically those using partial least square... more The application of multivariate calibration models, specifically those using partial least squares (PLS) regression to relate near infrared (NIR) spectral data to analyte concentrations, relies upon accurate knowledge of the concentrations during model building. In a physiologic system, ...
In vivo, noninvasive measurement of muscle pH during exercise using near infrared spectroscopy. [... more In vivo, noninvasive measurement of muscle pH during exercise using near infrared spectroscopy. [Proceedings of SPIE 6007, 60070N (2005)]. Olusola Soyemi, Michael Shear, Michelle Landry, Dulce Anunciacion, Babs Soller. Abstract. ...
Advanced Environmental and Chemical Sensing Technology, 2001
A new algorithm for the design of optical computing filters for chemical analysis otherwise known... more A new algorithm for the design of optical computing filters for chemical analysis otherwise known as Multivariate Optical Elements (MOEs), is described. The approach is based on the nonlinear correlation of the MOE layer thicknesses to the standard error in sample prediction for the chemical species of interest using a modified version ofthe Gauss-Newton nonlinear optimization algorithm. The design algorithm can either be initialized by random layer thicknesses or by a pre-existing design. The algorithm has been successfully tested by using it to design a MOE for the determination of copper uroporphynn in a quaternary mixture of uroporphyrin (freebase), nickel uroporphyrin, copper uroporphynn, and tin uroporphyrin.
Iterative target transformation factor analysis (ITTFA) was used to determine the spectra of the ... more Iterative target transformation factor analysis (ITTFA) was used to determine the spectra of the individual species generated during the oxidative p-doping of films of poly(para-phenyleneethynylene) (PPE). UV-visible spectra of PPE films on transparent electrodes were obtained in-situ during an anodic sweep. ITTFA identified 4 species present during the oxidation, which we assign as neutral polymer, polaron species, bipolaron species, and a species formed by further bipolaron reaction. The region of electrochemical stability for each of these species was identified and their potential-dependent profiles were obtained. This work is the first deconvolution of conjugated polymer spectroelectrochemistry.
We have demonstrated simultaneous correction for the optical interference of skin and fat in tiss... more We have demonstrated simultaneous correction for the optical interference of skin and fat in tissue spectra by using a two-distance fiber-optic probe. We obtained the correction by orthogonalizing the spectra collected at a long source-detector distance (SD) to the spectra collected at a short SD and mapped to the long SD space. The method was validated in tissuelike three-layer phantoms as well as preliminarily in human tissue. After the correction, a partial-least-squares model of the phantoms showed enhanced prediction performance.
The influence of fat thickness on the diffuse reflectance spectra of muscle in the near infrared ... more The influence of fat thickness on the diffuse reflectance spectra of muscle in the near infrared (NIR) region is studied by Monte Carlo simulations of a two-layer structure and with phantom experiments. A polynomial relationship was established between the fat thickness and the detected diffuse reflectance. The influence of a range of optical coefficients (absorption and reduced scattering) for fat and muscle over the known range of human physiological values was also investigated. Subject-to-subject variation in the fat optical coefficients and thickness can be ignored if the fat thickness is less than 5 mm. A method was proposed to correct the fat thickness influence.
Optical Fibers and Sensors for Medical Applications IV, 2004
ABSTRACT A visible-near IR (500-1,000nm) fiber optic sensor is under development that is intended... more ABSTRACT A visible-near IR (500-1,000nm) fiber optic sensor is under development that is intended to non-invasively assess muscle metabolism through the measurement of tissue pH and oxygen partial pressure. These parameters are calculated from the spectra of hemoglobin and myoglobin in muscle. The sensor consists of transmit (illumination) fibers and receive (detection) fibers that are coupled to a spectrometer. Light from the probe must penetrate below the surface of the skin and into a 5-10mm thick layer of muscle. A study was conducted to quantify the relationship between transmit and receive fiber separation and sensor penetration depth below the surface of the skin. A liquid phantom was created to replicate the absorption (mua) and reduced scatter coefficient (mus') profiles typically found in human blood and tissue. The phantom consisted of a solution of Intralipid and India ink in the appropriate concentrations to achieve desired reduced scatter coefficient and absorption profiles. The reduced scatter coefficient of the liquid phantom was achieved to an accuracy of +/-10% compared to previously published data. A fixed illumination fiber and translatable detector fiber were placed in the liquid phantom, and the fiber separation was varied from 3-40mm. Values of mua and mus' varied from 0.03-0.40 cm-1 and 5.0-15.0 cm-1 respectively. Results from the experiment demonstrate a strong correlation between penetration depth and fiber separation. Additionally, it was found that penetration depth was not substantially influenced by absorption and scatter concentration. As signal-to-noise is an important parameter in many non-invasive biomedical applications, the relative signal as a function of fiber separation was determined to follow an exponential relationship.
ABSTRACT Quantitative multivariate spectroscopic methods seek spectral patterns that correspond t... more ABSTRACT Quantitative multivariate spectroscopic methods seek spectral patterns that correspond to analyte concentrations even in the presence of interferents. By embedding a spectral pattern that corresponds to a target analyte in an interference filter in a ...
ABSTRACT In order to measure muscle physiological parameters such as pH and oxygen partial pressu... more ABSTRACT In order to measure muscle physiological parameters such as pH and oxygen partial pressure (PO2) by continuous wave (CW) diffuse reflectance near-infrared spectroscopy (NIRS), light must penetrate through skin and subcutaneous fat layers overlying muscle. In this study, the effect of skin and subcutaneous fat layer and on the spatial sensitivity profile of CW diffuse reflectance near-infrared spectra is investigated through Monte Carlo simulations. The simulation model uses a semi-infinite medium consisting of skin, fat and muscle. The optical properties of each layer are taken from the reported optical data at 750 nm. The skin color is either Caucasian or Negroid and the fat thickness is varied from 0 ~ 20 mm. The spatial sensitivity profile, penetration depth, and sensitivity ratio as functions of optical fiber source-detector separation (SD, 2.5 mm, 5.0 mm, 10.0 mm, 20.0 mm, 30.0 mm and 40.0 mm), skin color and fat thicknesses are predicted by the simulations. It is shown that skin color only slightly influenced the spatial sensitivity profile, while the presence of the fat layer greatly decreased the detector sensitivity. It is also shown that probes with longer SD separations can detect light from deeper inside the medium. The simulation results are used to design a fiber optic probe which ensures that enough light is propagated inside the muscle in NIRS measurement on a leg with a fat layer of normal thickness.
Smart Medical and Biomedical Sensor Technology IV, 2006
It is estimated that 750,000 cases of severe sepsis occur in the United States annually, at least... more It is estimated that 750,000 cases of severe sepsis occur in the United States annually, at least 225,000 of which are fatal, resulting in significant utilization of healthcare resources and expenses. Significant progress in the understanding of pathophysiology and treatment of ...
We have previously demonstrated the correlation of continuous-wave near infrared (CW-NIR) tissue ... more We have previously demonstrated the correlation of continuous-wave near infrared (CW-NIR) tissue measurements, to blood and tissue metabolic parameters using Partial Least Squares (PLS) regression. The practical use of this non-invasive measurement technique ...
ABSTRACT Multivariate Optical Computing (MOC) devices have the potential of greatly simplifying a... more ABSTRACT Multivariate Optical Computing (MOC) devices have the potential of greatly simplifying as well as reducing the cost of applying the mathematics of multivariate regression to problems of chemical analysis in the real world. These devices utilize ...
The application of multivariate calibration models, specifically those using partial least square... more The application of multivariate calibration models, specifically those using partial least squares (PLS) regression to relate near infrared (NIR) spectral data to analyte concentrations, relies upon accurate knowledge of the concentrations during model building. In a physiologic system, ...
ABSTRACT In order to measure muscle physiological parameters such as pH and oxygen partial pressu... more ABSTRACT In order to measure muscle physiological parameters such as pH and oxygen partial pressure (PO2) by continuous wave (CW) diffuse reflectance near-infrared spectroscopy (NIRS), light must penetrate through skin and subcutaneous fat layers overlying muscle. In this study, the effect of skin and subcutaneous fat layer and on the spatial sensitivity profile of CW diffuse reflectance near-infrared spectra is investigated through Monte Carlo simulations. The simulation model uses a semi-infinite medium consisting of skin, fat and muscle. The optical properties of each layer are taken from the reported optical data at 750 nm. The skin color is either Caucasian or Negroid and the fat thickness is varied from 0 ~ 20 mm. The spatial sensitivity profile, penetration depth, and sensitivity ratio as functions of optical fiber source-detector separation (SD, 2.5 mm, 5.0 mm, 10.0 mm, 20.0 mm, 30.0 mm and 40.0 mm), skin color and fat thicknesses are predicted by the simulations. It is shown that skin color only slightly influenced the spatial sensitivity profile, while the presence of the fat layer greatly decreased the detector sensitivity. It is also shown that probes with longer SD separations can detect light from deeper inside the medium. The simulation results are used to design a fiber optic probe which ensures that enough light is propagated inside the muscle in NIRS measurement on a leg with a fat layer of normal thickness.
Smart Medical and Biomedical Sensor Technology IV, 2006
It is estimated that 750,000 cases of severe sepsis occur in the United States annually, at least... more It is estimated that 750,000 cases of severe sepsis occur in the United States annually, at least 225,000 of which are fatal, resulting in significant utilization of healthcare resources and expenses. Significant progress in the understanding of pathophysiology and treatment of ...
We have previously demonstrated the correlation of continuous-wave near infrared (CW-NIR) tissue ... more We have previously demonstrated the correlation of continuous-wave near infrared (CW-NIR) tissue measurements, to blood and tissue metabolic parameters using Partial Least Squares (PLS) regression. The practical use of this non-invasive measurement technique ...
ABSTRACT Multivariate Optical Computing (MOC) devices have the potential of greatly simplifying a... more ABSTRACT Multivariate Optical Computing (MOC) devices have the potential of greatly simplifying as well as reducing the cost of applying the mathematics of multivariate regression to problems of chemical analysis in the real world. These devices utilize ...
The application of multivariate calibration models, specifically those using partial least square... more The application of multivariate calibration models, specifically those using partial least squares (PLS) regression to relate near infrared (NIR) spectral data to analyte concentrations, relies upon accurate knowledge of the concentrations during model building. In a physiologic system, ...
In vivo, noninvasive measurement of muscle pH during exercise using near infrared spectroscopy. [... more In vivo, noninvasive measurement of muscle pH during exercise using near infrared spectroscopy. [Proceedings of SPIE 6007, 60070N (2005)]. Olusola Soyemi, Michael Shear, Michelle Landry, Dulce Anunciacion, Babs Soller. Abstract. ...
Advanced Environmental and Chemical Sensing Technology, 2001
A new algorithm for the design of optical computing filters for chemical analysis otherwise known... more A new algorithm for the design of optical computing filters for chemical analysis otherwise known as Multivariate Optical Elements (MOEs), is described. The approach is based on the nonlinear correlation of the MOE layer thicknesses to the standard error in sample prediction for the chemical species of interest using a modified version ofthe Gauss-Newton nonlinear optimization algorithm. The design algorithm can either be initialized by random layer thicknesses or by a pre-existing design. The algorithm has been successfully tested by using it to design a MOE for the determination of copper uroporphynn in a quaternary mixture of uroporphyrin (freebase), nickel uroporphyrin, copper uroporphynn, and tin uroporphyrin.
Iterative target transformation factor analysis (ITTFA) was used to determine the spectra of the ... more Iterative target transformation factor analysis (ITTFA) was used to determine the spectra of the individual species generated during the oxidative p-doping of films of poly(para-phenyleneethynylene) (PPE). UV-visible spectra of PPE films on transparent electrodes were obtained in-situ during an anodic sweep. ITTFA identified 4 species present during the oxidation, which we assign as neutral polymer, polaron species, bipolaron species, and a species formed by further bipolaron reaction. The region of electrochemical stability for each of these species was identified and their potential-dependent profiles were obtained. This work is the first deconvolution of conjugated polymer spectroelectrochemistry.
We have demonstrated simultaneous correction for the optical interference of skin and fat in tiss... more We have demonstrated simultaneous correction for the optical interference of skin and fat in tissue spectra by using a two-distance fiber-optic probe. We obtained the correction by orthogonalizing the spectra collected at a long source-detector distance (SD) to the spectra collected at a short SD and mapped to the long SD space. The method was validated in tissuelike three-layer phantoms as well as preliminarily in human tissue. After the correction, a partial-least-squares model of the phantoms showed enhanced prediction performance.
The influence of fat thickness on the diffuse reflectance spectra of muscle in the near infrared ... more The influence of fat thickness on the diffuse reflectance spectra of muscle in the near infrared (NIR) region is studied by Monte Carlo simulations of a two-layer structure and with phantom experiments. A polynomial relationship was established between the fat thickness and the detected diffuse reflectance. The influence of a range of optical coefficients (absorption and reduced scattering) for fat and muscle over the known range of human physiological values was also investigated. Subject-to-subject variation in the fat optical coefficients and thickness can be ignored if the fat thickness is less than 5 mm. A method was proposed to correct the fat thickness influence.
Optical Fibers and Sensors for Medical Applications IV, 2004
ABSTRACT A visible-near IR (500-1,000nm) fiber optic sensor is under development that is intended... more ABSTRACT A visible-near IR (500-1,000nm) fiber optic sensor is under development that is intended to non-invasively assess muscle metabolism through the measurement of tissue pH and oxygen partial pressure. These parameters are calculated from the spectra of hemoglobin and myoglobin in muscle. The sensor consists of transmit (illumination) fibers and receive (detection) fibers that are coupled to a spectrometer. Light from the probe must penetrate below the surface of the skin and into a 5-10mm thick layer of muscle. A study was conducted to quantify the relationship between transmit and receive fiber separation and sensor penetration depth below the surface of the skin. A liquid phantom was created to replicate the absorption (mua) and reduced scatter coefficient (mus') profiles typically found in human blood and tissue. The phantom consisted of a solution of Intralipid and India ink in the appropriate concentrations to achieve desired reduced scatter coefficient and absorption profiles. The reduced scatter coefficient of the liquid phantom was achieved to an accuracy of +/-10% compared to previously published data. A fixed illumination fiber and translatable detector fiber were placed in the liquid phantom, and the fiber separation was varied from 3-40mm. Values of mua and mus' varied from 0.03-0.40 cm-1 and 5.0-15.0 cm-1 respectively. Results from the experiment demonstrate a strong correlation between penetration depth and fiber separation. Additionally, it was found that penetration depth was not substantially influenced by absorption and scatter concentration. As signal-to-noise is an important parameter in many non-invasive biomedical applications, the relative signal as a function of fiber separation was determined to follow an exponential relationship.
ABSTRACT Quantitative multivariate spectroscopic methods seek spectral patterns that correspond t... more ABSTRACT Quantitative multivariate spectroscopic methods seek spectral patterns that correspond to analyte concentrations even in the presence of interferents. By embedding a spectral pattern that corresponds to a target analyte in an interference filter in a ...
ABSTRACT In order to measure muscle physiological parameters such as pH and oxygen partial pressu... more ABSTRACT In order to measure muscle physiological parameters such as pH and oxygen partial pressure (PO2) by continuous wave (CW) diffuse reflectance near-infrared spectroscopy (NIRS), light must penetrate through skin and subcutaneous fat layers overlying muscle. In this study, the effect of skin and subcutaneous fat layer and on the spatial sensitivity profile of CW diffuse reflectance near-infrared spectra is investigated through Monte Carlo simulations. The simulation model uses a semi-infinite medium consisting of skin, fat and muscle. The optical properties of each layer are taken from the reported optical data at 750 nm. The skin color is either Caucasian or Negroid and the fat thickness is varied from 0 ~ 20 mm. The spatial sensitivity profile, penetration depth, and sensitivity ratio as functions of optical fiber source-detector separation (SD, 2.5 mm, 5.0 mm, 10.0 mm, 20.0 mm, 30.0 mm and 40.0 mm), skin color and fat thicknesses are predicted by the simulations. It is shown that skin color only slightly influenced the spatial sensitivity profile, while the presence of the fat layer greatly decreased the detector sensitivity. It is also shown that probes with longer SD separations can detect light from deeper inside the medium. The simulation results are used to design a fiber optic probe which ensures that enough light is propagated inside the muscle in NIRS measurement on a leg with a fat layer of normal thickness.
Smart Medical and Biomedical Sensor Technology IV, 2006
It is estimated that 750,000 cases of severe sepsis occur in the United States annually, at least... more It is estimated that 750,000 cases of severe sepsis occur in the United States annually, at least 225,000 of which are fatal, resulting in significant utilization of healthcare resources and expenses. Significant progress in the understanding of pathophysiology and treatment of ...
We have previously demonstrated the correlation of continuous-wave near infrared (CW-NIR) tissue ... more We have previously demonstrated the correlation of continuous-wave near infrared (CW-NIR) tissue measurements, to blood and tissue metabolic parameters using Partial Least Squares (PLS) regression. The practical use of this non-invasive measurement technique ...
ABSTRACT Multivariate Optical Computing (MOC) devices have the potential of greatly simplifying a... more ABSTRACT Multivariate Optical Computing (MOC) devices have the potential of greatly simplifying as well as reducing the cost of applying the mathematics of multivariate regression to problems of chemical analysis in the real world. These devices utilize ...
The application of multivariate calibration models, specifically those using partial least square... more The application of multivariate calibration models, specifically those using partial least squares (PLS) regression to relate near infrared (NIR) spectral data to analyte concentrations, relies upon accurate knowledge of the concentrations during model building. In a physiologic system, ...
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