Photoplethysmography and its application in clinical physiological measurement

http://www.kresttechnology.com/krest-academic-projects/krest-major-projects/ECE/B-Tech%20Papers/67.pdf

ECG signal denoising and baseline wander correction based on the empirical mode decomposition

Oscillating-water-column wave energy converters and air turbines: A review

McDonaldʼs Blood Flow in Arteries

Photoplethysmography (PPG) is a noninvasive optical technique for detecting microvascular blood volume changes in tissues. Its ease of use, low cost and convenience make it an attractive area of research in the biomedical and clinical communities. Nevertheless, its single spot monitoring and the need to apply a PPG sensor directly to the skin limit its practicality in situations such as perfusion mapping and healing assessments or when free movement is required. The introduction of fast digital cameras into clinical imaging monitoring and diagnosis systems, the desire to reduce the physical restrictions, and the possible new insights that might come from perfusion imaging and mapping inspired the evolution of the conventional PPG technology to imaging PPG (IPPG). IPPG is a noncontact method that can detect heart-generated pulse waves by means of peripheral blood perfusion measurements. Since its inception, IPPG has attracted significant public interest and provided opportunities to improve personal healthcare. This study presents an overview of the wide range of IPPG systems currently being introduced along with examples of their application in various physiological assessments. We believe that the widespread acceptance of IPPG is happening, and it will dramatically accelerate the promotion of this healthcare model in the near future.

/pdf/photoplethysmography-revisited-from-contact-to-noncontact-2jla840amb.pdf

Photoplethysmography Revisited: From Contact to Noncontact, From Point to Imaging

The objective of this work was to develop and validate a rapid, highly sensitive ultra performance\nliquid chromatography-tandem mass spectrometry (UPLC-ESI-MS/MS) method for the quantification\nof 2-isopropyl-4-(chloromethyl)thiazole in ritonavir. Chromatographic conditions of this impurity\nwere achieved on an AQUITY UPLC column HSS (high strength silica) T3 column (100 mm long, 2.1\nmm internal diameter, 1.8 μm diameter) using a gradient elution with 0.1% formic acid in water and\nmethanol at a flow rate of 0.3 mL/min. LCMS/MS was operated under the multiple reaction mode\n(MRM) using electrospray ionization technique in positive ion mode and the transitions of m/z\n176.1[M+H]+→140.1 for quantifier, 176.1[M+H]+→71.0 for qualifier were used to measure the\nimpurity, respectively. The total chromatographic run time was 10 min. Full validation of the analytical\nmethod was carried out, including its system precision, selectivity, linearity, accuracy, recovery,\nruggedness, stability and robustness. A linear response function was achieved in the concentration\nrange of 0.12-1.86 μg/g with r > 0.99. The detection limit and quantitation limit of this impurity were\n0.06 and 0.12 μg/g, respectively. Consistent recoveries were obtained during intra- and inter-day\nprecision experiments in validation ranged from 80-120%. The developed method could be helpful\nnot only for quality control and also for risk management of potential genotoxicity of this impurity in\nritonavir drug substance.

Development and Validation of UPLC-ESI-MS/MS Technique for theDetermination of 2-Isopropyl-4-(chloromethyl)thiazole in Ritonavir

A virtual instrumentation based scheme is developed for the characterization of magnetic materials. The principle used for measurement is derived from the comparison method of testing instrument transformers. A prototype has been developed by suitably modifying an instrument transformer test set. Characterization of magnetic materials at single frequency and multiple frequencies have been carried out. Typical test results obtained are presented in the paper. The developed instrument substantially reduces the testing time associated with magnetic characterization.

/pdf/characterizing-magnetic-materials-using-virtual-4crup5v3yj.pdf

Characterizing magnetic materials using virtual instrumentation

Measurement of current and voltage in high voltage systems employing optical fibre sensors is becoming increasingly popular as the problem of insulation is practically eliminated. Vibrations, physical and acoustic, perturb the polarisation-preserving sensing fibre and cause added noise much in excess of the signal. The present paper discusses a method for reconstructing such a signal. The method, namely, signal-averaging digital phase sensitive detection (DPSD) recovers the signal of any arbitrary wave shape buried in noise. The only requirements are that the signal should be periodic and a local reference should be made available, conditions easily met in HV systems. The efficacy of the scheme is demonstrated by experimental results on a fibre optic current sensor with non-sinusoidal current.

An Optical Fibre Sensor for Non-sinusoidal Current

A sensitive and rapid HPLC method was developed and validated for the determination of potential genotoxic impurities i.e (Bromomethyl)biphenyl methyl ester and (Dibromomethyl)biphenyl methylester at trace level in Telmisartan drug substance by applying the concept of threshold of toxicological concern (TTC). The HPLC method was developed and optimized on Symmetry Shield RP18, 3.5  (150mm × 4.6mm) column with oven temperature maintaining at 40°C and 0.02M Phosphate buffer pH 2.5 was chosen as mobile phase A and mixture of acetonitrile and Phosphate buffer (55:45) was selected as mobile phase B in gradient reverse phase mode in isocratic mode of composition. Chromatographic parameters i.e flow rate: 1.0 ml/min, wavelength detection: 205 nm, injection volume: 20μl and run time: 25 min were applied in this methodology. Based on validation data, the method is found to be specific, sensitive, accurate and precise. The established limits of Limit of detection and Limit of quantification for subjected impurities are found to be 2.4 μg/g and 4.7 μg/g respectively for each impurity. The recovery at LOQ level obtained was 98.2% for (Bromomethyl) biphenyl methyl ester and 99.2% for (Dibromomethyl) biphenyl methyl ester. This method can be used as good quality control tool for quantization of these impurities at low level. The experimental results are discussed in detail in this research paper.

http://ajptr.com/assets/upload/publish_article/AJPTR113003.pdf

Low Level Quantification of Potential Genotoxic Impurities In Telmisartan Drug Substance by HPLC

Objective. Noninvasive measurement of oxygen saturation (SpO 2) using transmissive photoplethysmography (tPPG) is clinically accepted and widely employed. However, reflective photoplethysmography (rPPG)—currently present in smartwatches—has not become equally accepted, partially because the pathlengths of the red and infrared PPGs are patient-dependent. Thus, even the most popular ‘Ratio of Modulation’ (R) method requires patient-dependent calibration to reduce the errors in the measurement of SpO 2 using rPPGs. Approach. In this paper, a correction factor or ‘pathlength ratio’ β is introduced in an existing calibration-free algorithm that compensates the patient-dependent pathlength variations, and improved accuracy is obtained in the measurement of SpO 2 using rPPGs. The proposed pathlength ratio β is derived through the analytical model of a rPPG signal. Using the new expression and data obtained from a human hypoxia study wherein arterial oxygen saturation values acquired through Blood Gas Analysis were employed as a reference, β is determined. Main results. The results of the analysis show that a specific combination of the β and the measurements on the pulsating part of the natural logarithm of the red and infrared PPG signals yields a reduced root-mean-square error (RMSE). It is shown that the average RMSE in measuring SpO 2 values reduces to 1 %. Significance. The human hypoxia study data used for this work, obtained in a previous study, covers SpO 2 values in the range from 70 % to 100 %, and thus shows that the pathlength ratio β proposed here works well in the range of clinical interest. This work demonstrates that the calibration-free method applicable for transmission type PPGs can be extended to determine SpO 2 using reflective PPGs with the incorporation of the correction factor β. Our algorithm significantly reduces the number of parameters needed for the estimation, while keeping the RMSE below the clinically accepted 2 %.

V. Jagadeesh Kumar

Papers

Development and Validation of UPLC-ESI-MS/MS Technique for theDetermination of 2-Isopropyl-4-(chloromethyl)thiazole in Ritonavir

Characterizing magnetic materials using virtual instrumentation

An Optical Fibre Sensor for Non-sinusoidal Current

Low Level Quantification of Potential Genotoxic Impurities In Telmisartan Drug Substance by HPLC

Accuracy enhancement in reflective pulse oximetry by considering wavelength-dependent pathlengths