0000000000264745
AUTHOR
Edgars Kviesis-kipge
showing 26 related works from this author
Optical Studies of the Capillary Refill Kinetics in Fingertips
2009
A new methodology for temporal analysis of the capillary refill processes by means of photoplethysmography (PPG) contact probe operating in the blue region of spectrum has been developed. A corresponding prototype device for finger measurements has been created and clinically tested. Results demonstrated that both AC and DC components of the blue PPG bio-signals are sensitive to the capillary occlusion and refill. Real-time measurements of the skin capillary refill kinetics by this technology can be used for noninvasive diagnostics of the peripheral perfusion disorders.
Wearable photoplethysmography device prototype for wireless cardiovascular monitoring
2014
The aim of the study was to develop a prototype system of the smart garment for real time telemetric monitoring of human cardiovascular activity. Two types of photoplethysmography (PPG) sensors for low noise and artefact free signal recording from various sites of the human body that were suitable for integration into smart textile were investigated. The reflectance sensors with single and multiple photodiodes based on "pulse-duration-based signal conversion" signal acquisition principle were designed and evaluated. The technical parameters of the system were measured both on bench and in vivo. Overall, both types of PPG sensors showed acceptable signal quality SNR 86.56±3.00 dB, dynamic ra…
Real-time analysis of skin capillary-refill processes using blue LED
2010
A method for analysis of skin capillary-refill processes in real time by means of reflection photoplethysmography (PPG) contact probe operating in the blue (438nm ± 30 nm) and infrared (938 nm ± 20 nm) regions of spectrum is proposed. The corresponding prototype hardware and software for measurements have been developed and tested in laboratory. Realtime measurements of finger capillary refill kinetics by this technology have been taken and analyzed. Results demonstrated that both AC and DC components of the blue PPG biosignal are sensitive to capillary occlusion and refill.
Wearable wireless photoplethysmography sensors
2008
Wearable health monitoring sensors may support early detection of abnormal conditions and prevention of their consequences. Recent designs of three wireless photoplethysmography monitoring devices embedded in hat, glove and sock, and connected to PC or mobile phone by means of the Bluetooth technology, are described. First results of distant monitoring of heart rate and pulse wave transit time using the newly developed devices are presented.
Effect of probe contact pressure on the photoplethysmographic assessment of conduit artery stiffness
2013
Currently, photoplethysmography (PPG) is a frequently studied optical blood pulsation detection tech- nique among biophotonic and biomedical researchers due to the fact that it shows high potential for estimating the arterial stiffness (AS). The extraction of diagnostically useful information requires standardized measurement pro- cedure with good repeatability. However, the effects of a crucially important factor—the optimal contact pressure (CP) of the probe—are often ignored. Also, CP values are not reported to evaluate those effects. It is hypothesized that AS estimated from PPG pulse wave 2nd derivative parameter b∕a is strongly inconsistent when recorded at nonoptimal probe CP. Our pi…
Portable remote photoplethysmography device for monitoring of blood volume changes with high temporal resolution
2016
The compact remote photoplethysmography device for monitoring of blood volume pulsations from human skin were developed. The prototype device comprises electronics board with twelve circullary oriented bright near-infrared LED illuminators, which are precisely controlled, high-speed video camera and battery charging circuit. Device was tested in laboratory and could be used for non-contact monitoring of human blood volume changes in palm.
Multi-spectral photoplethysmography technique for parallel monitoring of pulse shapes at different tissue depths
2011
A photoplethysmography (PPG) signal can provide very useful information about a subject's hemodynamic status in a hospital or home environment. A newly developed portable multi-spectral photoplethysmography device has been used for studies of 11 healthy subjects. Multi-spectral photoplethysmography (MS-PPG) biosensor intended for analysis of peripheral blood volume pulsations at different vascular depths has been designed and experimentally tested. Multi-spectral monitoring was performed by means of a three–wavelengths (405 nm, 660 nm and 780 nm) laser diode and a single photodiode with multi-channel signal output processing. The proposed methodology and potential clinical applications are …
Reliability of Hemodynamic Parameters Measured by a Novel Photoplethysmography Device
2011
Three channel photoplethysmography (PPG) signal pulse wave studies of the leg’s conduit arteries during rest conditions were performed. The obtained data of each channel showed similar values, proving arterial PPG as a reliable and repeatable method to assess arterial waveform parameters. A validation experiment was carried out by acquiring signals from three identical IR PPG sensors, which were placed on different sites over the leg’s conduit arteries during rest conditions. Coefficients of variation (CV) were calculated at a 95% confidence interval by comparing results of each subject during multiple attempts. This data processing leads us to certain criteria of improvements in our method…
Multimodal Device for Real-Time Monitoring of Skin Oxygen Saturation and Microcirculation Function
2019
The present study introduces a recently developed compact hybrid device for real-time monitoring of skin oxygen saturation and temperature distribution. The prototype involves a snapshot hyperspectral camera, multi-wavelength illuminator, thermal camera, and built-in computer with custom-developed software. To validate this device in-vivo we performed upper arm vascular occlusion on eight healthy volunteers. Palm skin oxygen saturation maps were analyzed in real-time using k-means segmentation algorithm and two-layer optical diffuse model. The prototype system demonstrated a satisfying performance of skin hyperspectral measurements in the spectral range of 507&ndash
Multi-spectral photoplethysmography biosensor
2011
A photoplethysmography (PPG) signal can provide very useful information about a subject's hemodynamic status in a hospital or home environment. A newly developed portable multi-spectral photoplethysmography device has been used for studies of 11 healthy subjects. The developed optical fiber biosensor comprises one multi-wavelength laser diode (405nm, 660nm and 780nm) and a single photodiode with multi-channel signal output processing and built in Li-ion accumulator; special software was created for visualization and measuring of the MS-PPG signals. ARM7TDMI-S LPC2148, NXP (founded by Philips) 32 bit processor with clock frequency of 60 MHz performs measurement and analysis of the signal.
Remote photoplethysmography device with adaptive illumination for skin microcirculation assessment
2020
Measuring blood perfusion is important in medical care. However, currently available devices to measure blood perfusion are bulky, expensive and not easy-to-use. In this work a compact and portable low-cost prototype device for remote monitoring of palm skin microcirculation has been developed. Presented device consists of precisely controlled near-infrared illuminators (760nm peak wavelength) and video camera. The device with the custom designed software provides stable uniform illumination of curved skin surfaces, using feedback algorithm. Verification tests of this device showed improvements in the quality of skin blood perfusion maps in the case when the feedback system was used.
Clinical measurements analysis of multi-spectral photoplethysmograph biosensors
2014
The developed portable multi-spectral photoplethysmograph (MS-PPG) optical biosensor device, intended for analysis of peripheral blood volume pulsations at different vascular depths, has been clinically verified. Multi-spectral monitoring was performed by means of a four – wavelengths (454 nm, 519 nm, 632 nm and 888 nm) light emitted diodes and photodiode with multi-channel signal output processing. Two such sensors can be operated in parallel and imposed on the patient’s skin. The clinical measurements confirmed ability to detect PPG signals at four wavelengths simultaneously and to record temporal differences in the signal shapes (corresponding to different penetration depths) in normal a…
Riga Group’s recent results on laser applications for skin diagnostics
2021
Abstract The laser-related activities are reviewed of the Biophotonics Laboratory at UL Institute of Atomic Physics and Spectroscopy following the previous ICSQE-2018 conference. Four recent research projects are considered, including one EC Horizon-2020 project, two European Regional Development Fund (ERDF) projects and one project funded by the Latvian Council of Science (LCS). The projects are generally aimed at developing new optical methods and technologies for non-invasive in-vivo skin assessment to facilitate the early diagnostics of skin malformations (including cancers). Most of the projects explore novel approaches of camera-based biomedical imaging to the clinical diagnostics and…
Snapshot hyperspectral system for noninvasive skin blood oxygen saturation monitoring
2018
The present study introduces recently developed compact hyperspectral snapshot system (device and software) for skin oxygen saturation monitoring. This prototype device involves compact snapshot hyperspectral camera, multi-wavelength illuminator, optical filter and crossed polarizers. The device was validated using reference color samples and and in-vivo during finger arterial occlusion tests. The prototype system demonstrated good performance of skin hyperspectral measurements in spectral range of 500-630nm. The results confirmed reliability of developed system for in-vivo assessment of skin blood oxygen saturation.
Wearable PPG Sensor Matrix for Cardiovascular Assessment
2014
Wearable biomonitoring systems and smart textiles for healthcare are gaining more importance and significance in the R&D sphere due to their potentials in healthcare and sports. Such biomonitoring systems offer a number of advantages in comparison to the conventional equipment proving mobility of the wearer during a long-term monitoring of vital parameters. There are different options to set up the physiological monitoring using wireless and wearable technologies. One of the scenarios is addressing textiles as a carrier of electronics. Moreover, those differ by their functional applications, registered physiological parameters and technology solutions. Still, the most demanded biomonitoring…
Multimodal imaging device for skin diagnostics: improvements and tests
2018
In our work we have demonstrated our developed skin diagnostic imaging device and its hardware and software improvements. The device was tested in laboratory, to determine the stability of light uniformity and stability, as well as the performance of data processing. The improvements were focused to fulfill all requirements of doctors-dermatologists who use this device. Results showed that light field uniformity and stability were acceptable to get chromophore concentration maps of skin malformations.
A photoplethysmography device for multipurpose blood circulatory system assessment
2011
A novel method for photoplethysmography (PPG) signal detection has been proposed and implemented in a three channel prototype device. The current design is simple, low cost and does not require sophisticated analogue circuits. The prototype was evaluated by physiological measurements and recorded PPG signals from conduit arteries of human subject.
Wireless photoplethysmography finger sensor probe
2010
A sensitive, digital, wireless sensor probe has been developed for photoplethysmography (PPG) measurements. It uses standard light emitting source and detector. The main advantage of this approach is to measure discharge time of the photodiode as amplitude of PPG signal. It reduces the cost, dimensions, power consumption and filtering of the device. First results of distant monitoring of heart rate using the newly developed sensor probe are presented.
Miniature wireless photoplethysmography devices: integration in garments and test measurements
2012
Wireless PPG devices were developed and embedded in everyday clothes (bandage, scarf, cycling glove and wrist strap) to monitor cardiovascular state of free-moving persons. The corresponding software for measurements also has been developed and tested in laboratory. Real-time measurements of PPG signals were taken in parallel with a professional ECG reference device, and high correlation was demonstrated.
Express RGB mapping of three to five skin chromophores
2017
Skin melanin, oxy- and deoxy-hemoglobin were snapshot-mapped under simultaneous 448-532-659 nm laser illumination by a smartphone RGB camera. Experimental prototypes for double-snapshot RGB mapping of four (melanin, bilirubin, oxy- and deoxy-hemoglobin) and five (melanin, bilirubin, lipids, oxy- and deoxy-hemoglobin) skin chromophores with reduced laser speckle artefacts have been developed and tested. A set of 405-448-532-659 nm lasers were used for four chromophores mapping, and a set of 405-448-532-659-842 nm lasers for five chromophores mapping. Clinical tests confirmed functionality of the developed devices.
Optosko metožu un ierīču izstrāde kardiovaskulārā stāvokļa kontrolei reālā laikā
2013
ANOTĀCIJA Promocijas darbā izstrādātas divas jaunas optiskas metodes cilvēka veselības stāvokļa novērtēšanai reālā laikā - fotopletizmogrāfijas (PPG) signālu digitālās detektēšanas metode un metode rekapilarizācijas procesa izsekošanai pēc PPG signālu izmaiņām spektra zilajā daļā. Piedāvāti jauni tehniskie risinājumi arī bezvadu PPG, vairākkanālu PPG un multispektrālās PPG realizācijā. Jaunās un pilnveidotās metodes realizētas praksē, izstrādājot un eksperimentāli pārbaudot piecas oriģinālas mērierīces fizioloģisko parametru noteikšanai un monitoringam. PPG signālu bezvadu detektēšanas, apstrādes un pārraides iekārtās izmantota Bluetooth datu pārraide un mūsdienīgu raidītājmoduļu piedāvātās…
Novel hybrid technology for early diagnostics of sepsis
2017
Sepsis is a potentially fatal disease with mortality rate as high as 50% in patients with septic shock; mortality rate can increase by 7.6% per hour if appropriate treatment is not started. Internationally accepted guidelines for diagnosis of sepsis rely on vital sign monitoring and laboratory tests in order to recognize organ failure. This pilot study aims to explore the potential of hyperspectral and thermal imaging techniques to identify and quantify early alterations in skin oxygenation and perfusion induced by sepsis. The study comprises both physiological model experiments on healthy volunteers in a laboratory environment, as well as screening case series of patients with septic shock…
Imaging photoplethysmography for assessment of chronic pain patients
2019
In present pilot study application of multi-spectral imaging photoplethysmography for assessment of chronic pain patients during topical skin heating test was proposed. Photoplethysmography signal was recorded at 420nm, 530nm and 810nm illumination from the skin and corresponding perfusion indexes and perfusion maps were calculated. The novel parameter-PPGflare index was introduced and compared in neuropathic patients and healthy volunteers. Preliminary results suggest that neuropathic patients exhibited significantly lower PPGflare index, and that local heating substantially change PPG waveform at heat exposed skin region. Present study emphasizes advantages of imaging photoplethysmography…
Optisko metožu un ierīču izstrāde kardiovaskulārā stāvokļa kontrolei reālā laikā
2013
Elektroniskā versija nesatur pielikumus
Bezvadu fotopletizmogrāfijas izmantošana veselības monitoringam
2008
Maģistra darbā ir pētītas bezvadu fotopletizmogrāfijas (PPG) metodes izmantošanas iespējas veselības monitoringam. Darba izpildes laikā tika izgatavotas oriģinālas PPG signāla detektēšanas, apstrādes un pārraides ierīces. Tās balstītas uz biometrisko datu pārraidi nelielā attālumā (~10 m) izmantojot Bluetooth moduli. Ierīces mēģinātas iestrādāt dažādos ikdienā biežāk lietojamos apģērba gabalos (cimdā, zeķē, cepurē). Darbā sniegts pārskats par fotopletizmogrāfijas vēsturi, aprakstītas jaunradīto ierīču konstrukcijas, veikti mērījumu apkopojumi, izskaidroti bezvadu PPG signālu pārraides principi un iespējas. Rezultāti liecina, ka ar izstrādāto bezvadu mērīšanas ierīci var ērti mērīt un novēro…
Mālu slāņkopas uzbūve, sastāvs un veidošanās Lielauces atradnē
2006
Bakalaura darbā ir raksturota māla slāņkopas sastāvs un uzbūve Lielauces māla karjerā, kā arī izdarīti secinājumi par mālu veidošanās apstākļiem. Šīs atradnes mālainie nogulumi, izņemot atradnes izpētes darbus, nav tikuši visai detalizēti raksturoti. Svarīgi atzīmēt, ka Lielauces atradne ir viena no šobrīd retajām kvartāra māla iegulām, kur notiek ieguve, tādēļ pētījumiem ir pieejamas neapbirušas un neapaugušas sienas. Iepriekšējos gados ir iesākti Latvijas glaciolimnisko mālu tekstūru pētījumi, un šo pētījumu autori V. Kuršs, A. Stinkule u.c. ir rekomendējuši turpināt šos darbus. Darba mērķis ir noskaidrot pleistocēna glaciolimnisko mālu slāņkopas uzbūvi, sastāvu un veidošanās apstākļus Li…