Michal Boltrukiewicz

Novel approach to processing of a PPG signal

The subject of the paper is devoted to optoelectronic acquisition and processing of the pulse waveform of arterial blood, which contributes as the major component to peripheral photoplethysmographic signal. Considered questions concern problems with reliable processing of noninvasively acquired biooptical signals that are influenced by noises, artifacts and other disturbances. The proposed procedures of signal conditioning make possible effective acquisition of useful parameters of a raw noisy PPG signal. Novel design of the adherence circuit that allows eliminating the disturbing low-frequency trend has been presented. Results of verifying studies, where real signals acquired with transmission sensor were processed using this and circuit and classical linear circuit, are discussed.

Computer-Assisted Acquisition and Statistical Evaluation of Multifocal Visual Evoked Potentials

The subject of this paper concerns the electro-physiological examination of the visual organ, the acquisition and statistical evaluation of the multifocal visual evoked potentials (M-VEP), in particular. The results presented are related to the real multifocal VEP waveforms, obtained during the examination of numerous patients in clinical conditions. The statistical evaluation of the results obtained during the examination of numerous healthy eyes enables the determination of electrical potential tolerance intervals and latency in the scope of the entire visual path of a healthy eye. Due to the lack of standardized values of the M-VEP test, the intervals may represent reference data in the valuation of various visual tract diseases. The data included therein, upon being exported to Microsoft Excel, enable the calculation of the average and standard deviation, and the tolerance intervals based on them

Utilization of human-computer interaction in wireless transmission of arterial pulse waveforms

The shape of the arterial pulsations depends upon the thickness of the blood vessels and contractility of the heart as well as the state of the vascular smooth muscle in the vessel wall. Photoplethysmography (PPG) is by definition an optoelectronic method for measuring and recording changes in volume of a body part. The shape and stability of the PPG waveform can be used as an indication of possible motion artifacts or low perfusion conditions. Furthermore, the photoplethysmogram reveals circulatory depression and arrhythmia. In the paper, we propose a system that allows wireless transmitting of peripheral arterial pulse waveforms with use of a GPRS network. Selected examples of results, which were obtained during investigations made on a number of real PPG signals, are presented.

Modeling of arterial pulse waveforms for virtual reconstruction and measurements

The subject of this paper is concerned with utilization of virtual reality in biomeasurements. Biomedical signals carry information that is often enclosed in a signal shape. Problems connected with modeling and simulations of the arterial blood pulse waveform are considered. This waveform is a major component of a given plethysmographic signal that may be acquired form various body sites with noninvasive sensors. Basing on selective biooptical properties of human tissues, using optoelectronic sensors allows acquiring photoplethysmographic (PPG) signals. The PPG signal may be considered as the response of a given dynamic system to an input cyclical signal that is quasi-periodical. The known descriptions of PPG attributes are mostly non-parametrical. On the contrary, a way of parametrical description using the methods, which are utilized to identify dynamic systems, is presented in this paper. The ARMAX structure has been utilized as a base of mathematical modeling. The maximum likelihood method was used in identification of investigated PPG signals. Efficiency of the proposed reconstruction procedure has been tested on processing of real signals.

Conditioning of the signal to be acquired from a photoplethysmographic sensor

The subject of the paper is devoted to noninvasive acquisition of parameters specifying a photoplethysmographic signal (PPG) to which the pulse waveform contributes as the major component. Continuous monitoring ofphotoplethysmograms is of great importance in clinical practice. An optoelectronic sensor based either on reflection or transmission variant of lighttissue interaction can be used to detect the PPG signal, however, there are a lot of difficult measurement problems. Reliability of noninvasive optical sensing depends on specific factors, including physiological as well as technical interferences. In the paper, application of selected manners of digital filtration, which were used to process the raw signals acquired from an optoelectronic sensor placed on the fmgertip, is presented. The transmission variant oflight penetration is considered. The proposed procedures of signal conditioning allow making possible effective acquisition of useful parameters of a raw noisy PPG signal. Measurable quantitative changes caused by qualitative changes in a given pulse waveform shape and disturbances may be evaluated.

Accuracy analysis of a mathematical model of the pulse waveform

In the paper the accuracy of a mathematical model of the arterial blood pulse waveform is discussed. The valeus of square means error and correlation coefficient between a pulse waveform and response of its model are given. The methods of model accuracy improvement are considered. The results of numerical adjustment of pulse waveform model are presented.

Verification of a model of the system-generating PPG signals

The subject of this paper relates to the measurable effects of light behavior in biological materials. The modulations of biooptical signals, induced in tissues by arterial pulsations, are the basis of photoplethysmography (PPG), which by definition is an optoelectronic method for measuring and recording changes in volume of a body part. The PPG signal may be considered as the response of a given dynamic system to an input cyclical signal that is quasi-periodical. In the literature, the PPG attributes have been presented many times; however, the descriptions are mostly non-parametrical. On the contrary, a way of parametrical description using the methods that are utilized to identify dynamic systems is considered in this paper. A flow model and its mathematical description have been presented.

Simulation of microimages emitted by virtual array of testing oligonucleotides

This paper is concerned with utilization of virtual reality in biomeasurements. Presented questions have focused on predicting changes in the virtual optical response as a result of simulated changes in a considered DNA sequence composition. Relationships between thermodynamic and optical properties of a given sequence are taken in considering a light-directed library of testing oligonucleotides. The oligonucleotides embedded in the library volume make the array of short known sequences that are assumed as the testers. Simulated microimages entitled by a virtual array correspond to the sites where hybridization process is performed as a result of the DNA sequence base pairing characteristics. Presented simulation refers to changes in fluorescence signals to be sensed from the lighting array made by pixels, which intensities depend on parameters of the objects located in particular array sites.

Interpretation of the fluorescence image acquired for DNA sequencing

This paper is devoted to problems with reliability of the fluorescence analysis in investigating the DNA chains. Relationships between thermodynamic and optical properties of a given sequence are taken to consider modeling of a virtual light-directed library of oligonucleotides. Specificity of changes in optical density caused by specific interactions between pairs of DNA bases depends on the known nearest neighbor model which has been assumed here as the background. If to assume an integrated array of the known oligonucleotides (L-mers) which all have their own stable locations, after hybridization we may obtain a fluorescence result creating a matrix of micro-images; each one corresponds to the optical answer of a given oligonucleotide included in the investigated sequence spectrum. A presented concept of interpretation of fluorescence effects depends on relation between a given level of optical density and order of the bases included in oligonucleotides involved in hybridization procedure. The factors influencing fluorescence image attributes, including signal levels and stability as well as resolution and accuracy of sensing, are discussed. The obtained results of comparative computations made on a normal and simulated abnormal composition of a given human sequence are illustrated at the case that L = 6. Basing on consequences of changes in melting temperature, thermodynamic stability and levels of fluorescence light intensity, the optical spectra are presented as images made by sites of full hybridization put on a reference thermal map.