Home Improved FPGA controlled artificial vascular system for plethysmographic measurements
Article Open Access

Improved FPGA controlled artificial vascular system for plethysmographic measurements

  • Daniel Laqua EMAIL logo , Carina Brieskorn , Jan Hannes Koch , Markus Rothmayer , Steve Zeiske , Marcel Böttrich and Peter Husar
Published/Copyright: September 30, 2016
Download Article (PDF)
Become an author with De Gruyter Brill
Author Information Explore this Subject
Current Directions in Biomedical Engineering
From the journal Current Directions in Biomedical Engineering Volume 2 Issue 1

Abstract

The fetal oxygen saturation is an important parameter to determine the health status of a fetus, which is until now mostly acquired invasively. The transabdominal, fetal pulse oximetry is a promising approach to measure this non-invasively and continuously. The fetal pulse curve has to be extracted from the mixed signal of mother and fetus to determine its oxygen saturation. For this purpose efficient algorithms are necessary, which have to be evaluated under constant and reproducable test conditions. This paper presents the improved version of a phantom which can generate artificial pulse waves in a synthetic tissue phantom. The tissue phantom consists of several layers that mimic the different optical properties of the fetal and maternal tissue layers. Additionally an artificial vascular system and a dome, which mimics the bending of the belly of a pregnant woman, are incorporated. To obtain data on the pulse waves, several measurement methods are included, to help understand the behavior of the signals gained from the pulse waves. Besides pressure sensors and a transmissive method we integrated a capacitive approach, that makes use of the so called “Pin Oscillator” method. Apart from the enhancements in the tissue phantom and the measurements, we also improved the used blood substitute, which reproduces the different absorption characteristics of fetal and maternal blood. The results show that the phantom can generate pulse waves similar to the natural ones. Furthermore, the phantom represents a reference that can be used to evaluate the algorithms for transabdominal, fetal pulse oximetry.

Keywords: artificial pulse wave; artificial tissue phantom; artificial vessel system; fetal pulse oximetry

1 Introduction

The fetal oxygen saturation is an important parameter to determine the health of the fetus during labor or delivery. Current measurement methods are mostly invasive and non-continuous. They come along with several risks for mother and fetus. Therefore, it is desirable to develop non-invasive procedures for measuring the arterial oxygen saturation of the fetus. The transabdominal fetal pulse oximetry offers this possibility.

As we measure a mixed signal, which contains maternal and fetal components, a separation has to be performed [1]. To achieve this, complex algorithms need to be developed. To test them we need controlled and constant test conditions, as well as measurements to determine the signal behavior of the generated pulse waves. In [2] we presented an artificial vascular system, which models an arterial vascular system of mother and fetus and allows the generation and measurement of reproduced pulse waves.

To accomplish this, a pump builds up pressure in a pre-pressure system. To generate a pulsation of the artificial vascular system, proportional valves are rhythmically opened. The measurements are conducted in a synthetic tissue phantom, which is built of several layers of silicone, to mimic the different optical properties of mother, amniotic fluid and fetus. Several means of measuring the pulse waves are integrated into this phantom. The whole setup is controlled by a FPGA-system, that also records the data.

However, the former phantom [2] does not model the curvature of the belly during pregnancy. To reproduce this condition, the part with the artificial tissue was redesigned and is now incorporating a spherical part. Additionally, a capacitive sensor, molded into the artificial tissue, allows to measure the mechanical dilatation of the artificial vessel continuously. As third improvement two synthetic blood substitutes were developed which emulate the light absorption properties of fetal and maternal blood. These improvements, as well as results, are reported in the following sections.

Figure 1 System overview of the complete artificial vascular system with the main controlling unit NI cRIO-9074; The hydraulic system includes all mechanical parts and the data acquisition connects all sensors.
Figure 1

System overview of the complete artificial vascular system with the main controlling unit NI cRIO-9074; The hydraulic system includes all mechanical parts and the data acquisition connects all sensors.

2 Material and methods

The artificial tissue phantom is a simplified model of the abdomen of a pregnant woman and a part of the complete phantom. A sketch of it is depicted in Figure 2. It consists of three plane tissue layers and one bone layer, which mimic the optical properties of the maternal and fetal tissue [3]. Furthermore, the tissue phantom is separated into two sections. In the front section, there is an additional dome (5) placed on top of the tissue layers. The geometry of the dome is based on the convex shape of the abdomen of a pregnant woman. The rear section has a plane surface and contains three sensor boards for capacitive and photoplethysmographic measurements. Different kinds of tissue, like muscles, fat etc. are combined to a maternal (4) and a fetal layer (2). Furthermore the amniotic fluid is simulated by an additional layer (3) and embedded between the maternal and fetal layer. The tissue layers mainly consist of RTV-2 silicone, used as the host material. RTV-2 is an addition-vulcanising two-component silicone that vulcanizes at room temperature. It is transparent and has an elasticity similar to human tissue. By adding different additives to the RTV-2 silicone its properties can be modulated to comply with the optical properties of the tissue substitutes. The scattering and absorption properties are adjusted by using TiO2 and cosmetic powder. Each tissue layer contains different additive concentrations as shown in Table 1.

Figure 2 The sketch of the artificial tissue phantom shows the following component parts: (1) bottom layer, (2) fetal layer, (3) amniotic fluid, and (4) maternal tissue with the (5) dome.
Figure 2

The sketch of the artificial tissue phantom shows the following component parts: (1) bottom layer, (2) fetal layer, (3) amniotic fluid, and (4) maternal tissue with the (5) dome.

Table 1

Additive concentration of the tissue layers in relation to their total mass.

LayerAdditive concentration c in %
TiO2powder
fetal tissue0.72680.1085
amniotic fluid0.0210
maternal tissue0.74730.0695
dome0.74730.0695

To simulate the vascular system there are transparent silicone tubes embedded in the maternal and fetal layer. These tubes are connected to an artificial vascular system and a pressure system, which generates the pulse waves of the mother and the fetus. The pulse waves can be measured by detecting the change of the tube diameter, caused by variation of the internal pressure. The bottom layer (1) of the tissue phantom represents a large areal bone similar to the fetal head. In order to improve the signal quality during the reflective photoplethysmographic measurement, a total reflecting metal plate is used as the bone layer. The dome of the phantom has a curvature-radius of 118.3 mm. It is designed for a maximal sensor-detector distance of 100 mm. The thickness of the maternal tissue, which is composed of the dome and the plane layer, adds to 24 mm at the contact points of sensor and detector.

Besides appropriate substitutes for the tissue phantom, there was also the need of a synthetic blood fluid, which reproduces the optical properties of human blood. These are dependent on the different blood components, like plasma or cells, which exhibit varying optical attributes across the light spectrum. As it is very difficult to fully mimic these characteristics, the light-absorbing behavior of blood is mostly reproduced for one specific wavelength. One main topic of this work is the development of two blood surrogates with different absorption coefficients for the fetal and the maternal circuit. The absorption was realized by a mixture of distilled water and black ink. Two different mixtures were produced. One mixture mimics fetal blood with an oxygen saturation of 60%, whereas the second mixture simulates an oxygen saturation of 98% for maternal blood.

The formula used to calculate the concentration of the ink for a wavelength of λ = 633 nm was as follows:

(1)μaT⁢u=μaT⁢u%⋅cT⁢u

μaT⁢u corresponds to the total absorption coefficient of the blood surrogate, which is composed of the normalized absorption coefficient μaT⁢u% and the required concentration of black ink cTu. The absorption coefficients of human blood with oxygen saturations of 60% and 98% were taken from [4]. A value for the normalized absorption coefficient μaT⁢u% was presented in [5]. The resulting ink concentrations for the different optical properties of the human blood are shown in Table 2. The scattering characteristics of arterial blood can be emulated by mixing the blood substitute with additives such as milk or intralipids, as was reported in [6], [7], [8]. However, the absorption is the most important property for our first investigations, so we did not model the scattering.

Table 2

Optical properties of human blood, ink and calculated ink concentrations.

oxygen saturationμaT⁢uμaT⁢u%cTu
60%15.326.8440.57%
98%7.726.8440.27%
Figure 3 Principle of the “Pin Oscillator” method [9].
Figure 3

Principle of the “Pin Oscillator” method [9].

The former phantom used pressure sensors and transmissive light measurements to gain data on the pulse waves as reference. As a further improvement a capacitive measurement method was now implemented. The principle technique is the so called “Pin Oscillator” method [9] (s. Figure 3). An oscillator is built of a conductive sensor element and a specially designed μC. The oscillation frequency of the system depends on the capacity value of the sensor element, which is directly related to the dilation of the artificial vessel. The microcontroller counts the oscillation cycles, which represent the response time of the sensor. The measurement starts with an interrupt, which is generated by the FPGA-system and sent via a pin of the digital I/O-module. Data transmission is realized by a UART-protocol with the same module. Fetal and maternal vessels are measured separately. In Figure 1 all possibilities for data acquisition of the new phantom are depicted.

3 Results

The development of the new artificial tissue phantom, including the new measurement method, comes along with several benefits. The dome allows measuring conditions that are closer to the anatomy of a pregnant woman. The improved phantom allows the acquisition of further data for evaluating signal processing strategies to separate the fetal and maternal pulse curves gained with transabdominal fetal pulse oximetry.

Figure 4 Capacitive and pressure measurements of the maternal circuit.
Figure 4

Capacitive and pressure measurements of the maternal circuit.

Figure 4 shows exemplary capacitive and pressure measurements of the maternal circuit. As can be seen, the unfiltered signal shows a noise-like behavior. For better evaluation we applied a moving average filter with the length of 10 samples to mitigate this property. A much smoother signal curve is the result. A comparison between the pressure and the capacitive signal shows a very good congruence among the main peaks. This proves the validity of the capacitive measurement. Due to the high sensitivity of the measurements, the dicrote wave is more distinct.

The two blood substitutes realize different absorption characteristics close to the natural ones and create more realistic measuring conditions. The phantom therefore may be a first step towards a synthetic reference for calibration of pulse oximetry systems. As the measuring time could be expanded to approximately 4 minutes a sufficient amount of data can be acquired, which allows profound statements on the gathered data.

4 Conclusion

In this paper we presented the improved version of a phantom that is capable of producing and measuring artificial pulse waves for the test of algorithms for transabdominal fetal pulse oximetry. In addition to the improved measurement time of several minutes with two different blood surrogates, the capacitive measurement provides us with an extended data base, to improve the evaluation of the reflectively measured data.

Further improvements can be made regarding the scattering characteristics of the blood surrogate. However this is of minor urgency, as it seems that the properties are sufficient in their present state. The phantom with its hydraulic part may also be utilized in other fields of research by adapting the tissue phantom. A potential application could be microwave imaging, however there are also other possibilities imaginable.

Author’s Statement

Research funding: The author state no funding involved. Conflict of interest: Authors state no conflict of interest. Informed consent: Informed consent is not applicable. Ethical approval: The conducted research is not related to either human or animals use.

References

[1] Böttrich M, Ley S, Husar P. Simulation study on the effect of tissue geometries to fluence composition for non-invasive fetal pulse oximetry. 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) 2015. p. 5122–5125.10.1109/EMBC.2015.7319544Search in Google Scholar PubMed

[2] Laqua D, Brieskorn C, Koch JH, Rothmayer M, Zeiske S, Bóttrich M, et al. FPGA controlled artificial vascular system. Curr Dir Biomed Eng. 2015;1.10.1515/cdbme-2015-0107Search in Google Scholar

[3] Gan KB, Zahedi E, Mohd Ali MA. Investigation of optical detection strategies for transabdominal fetal heart rate detection using three-layered tissue model and Monte Carlo simulation. Appl Opt. 2011;41:885–896.Search in Google Scholar

[4] Roggan A, Friebel M, Dórschel K, Hahn A, Müller G. Optical properties of circulating human blood in the wavelength range 400–2500 nm. J Biomed Opt. 1999;4:36–46.10.1117/1.429919Search in Google Scholar PubMed

[5] Ley S, Stadthalter M, Link D, Laqua D, Husar P. Phantom materials mimicking the optical properties in the near infrared range for non-invasive fetal pulse oximetry. 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. Chicago, IL, USA 2014. p. 1432–1435. IEEE.10.1109/EMBC.2014.6943869Search in Google Scholar PubMed

[6] Pogue BW, Patterson MS. Review of tissue simulating phantoms for optical spectroscopy, imaging and dosimetry. J Biomed Opt. 2006;11:041102.10.1117/1.2335429Search in Google Scholar PubMed

[7] Stuban N, Niwayama M, Santha H. Phantom with pulsatile arteries to investigate the influence of blood vessel depth on pulse oximeter signal strength. Sensors. 2012;12:895–904.10.3390/s120100895Search in Google Scholar PubMed PubMed Central

[8] van Staveren HJ, Moes CJ, van Marie J, Prahl S, van Gemert MJ. Light scattering in Intralipid-10% in the wavelength range of 400–1100 nm. Appl Opt. 1991;30:4507–14.10.1364/AO.30.004507Search in Google Scholar PubMed

[9] Texas Instruments. MSP430 Low Cost PinOsc Capacitive Touch Overview. Available from: http://processors.wiki.ti.com/index.php/MSP430_Low_Cost_PinOsc_Capacitive_Touch_Overview.Search in Google Scholar

Published Online: 2016-9-30
Published in Print: 2016-9-1

©2016 Daniel Laqua et al., licensee De Gruyter.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Articles in the same Issue

  1. Synthesis and characterization of PIL/pNIPAAm hybrid hydrogels
  2. Novel blood protein based scaffolds for cardiovascular tissue engineering
  3. Cell adhesion and viability of human endothelial cells on electrospun polymer scaffolds
  4. Effects of heat treatment and welding process on superelastic behaviour and microstructure of micro electron beam welded NiTi
  5. Long-term stable modifications of silicone elastomer for improved hemocompatibility
  6. The effect of thermal treatment on the mechanical properties of PLLA tubular specimens
  7. Biocompatible wear-resistant thick ceramic coating
  8. Protection of active implant electronics with organosilicon open air plasma coating for plastic overmolding
  9. Examination of dielectric strength of thin Parylene C films under various conditions
  10. Open air plasma deposited antimicrobial SiOx/TiOx composite films for biomedical applications
  11. Systemic analysis about residual chloroform in PLLA films
  12. A macrophage model of osseointegration
  13. Towards in silico prognosis using big data
  14. Technical concept and evaluation of a novel shoulder simulator with adaptive muscle force generation and free motion
  15. Usability evaluation of a locomotor therapy device considering different strategies
  16. Hypoxia-on-a-chip
  17. Integration of a semi-automatic in-vitro RFA procedure into an experimental setup
  18. Fabrication of MEMS-based 3D-μECoG-MEAs
  19. High speed digital interfacing for a neural data acquisition system
  20. Bionic forceps for the handling of sensitive tissue
  21. Experimental studies on 3D printing of barium titanate ceramics for medical applications
  22. Patient specific root-analogue dental implants – additive manufacturing and finite element analysis
  23. 3D printing – a key technology for tailored biomedical cell culture lab ware
  24. 3D printing of hydrogels in a temperature controlled environment with high spatial resolution
  25. Biocompatibility of photopolymers for additive manufacturing
  26. Biochemical piezoresistive sensors based on pH- and glucose-sensitive hydrogels for medical applications
  27. Novel wireless measurement system of pressure dedicated to in vivo studies
  28. Portable auricular device for real-time swallow and chew detection
  29. Detection of miRNA using a surface plasmon resonance biosensor and antibody amplification
  30. Simulation and evaluation of stimulation scenarios for targeted vestibular nerve excitation
  31. Deep brain stimulation: increasing efficiency by alternative waveforms
  32. Prediction of immediately occurring microsleep events from brain electric signals
  33. Determining cardiac vagal threshold from short term heart rate complexity
  34. Classification of cardiac excitation patterns during atrial fibrillation
  35. An algorithm to automatically determine the cycle length coverage to identify rotational activity during atrial fibrillation – a simulation study
  36. Deriving respiration from high resolution 12-channel-ECG during cycling exercise
  37. Reducing of gradient induced artifacts on the ECG signal during MRI examinations using Wilcoxon filter
  38. Automatic detection and mapping of double potentials in intracardiac electrograms
  39. Modeling the pelvic region for non-invasive pelvic intraoperative neuromonitoring
  40. Postprocessing algorithm for automated analysis of pelvic intraoperative neuromonitoring signals
  41. Best practice: surgeon driven application in pelvic operations
  42. Vasomotor assessment by camera-based photoplethysmography
  43. Classification of morphologic changes in photoplethysmographic waveforms
  44. Novel computation of pulse transit time from multi-channel PPG signals by wavelet transform
  45. Efficient design of FIR filter based low-pass differentiators for biomedical signal processing
  46. Nonlinear causal influences assessed by mutual compression entropy
  47. Comparative study of methods for solving the correspondence problem in EMD applications
  48. fNIRS for future use in auditory diagnostics
  49. Semi-automated detection of fractional shortening in zebrafish embryo heart videos
  50. Blood pressure measurement on the cheek
  51. Derivation of the respiratory rate from directly and indirectly measured respiratory signals using autocorrelation
  52. Left cardiac atrioventricular delay and inter-ventricular delay in cardiac resynchronization therapy responder and non-responder
  53. An automatic systolic peak detector of blood pressure waveforms using 4th order cumulants
  54. Real-time QRS detection using integrated variance for ECG gated cardiac MRI
  55. Preprocessing of unipolar signals acquired by a novel intracardiac mapping system
  56. In-vitro experiments to characterize ventricular electromechanics
  57. Continuous non-invasive monitoring of blood pressure in the operating room: a cuffless optical technology at the fingertip
  58. Application of microwave sensor technology in cardiovascular disease for plaque detection
  59. Artificial blood circulatory and special Ultrasound Doppler probes for detecting and sizing gaseous embolism
  60. Detection of microsleep events in a car driving simulation study using electrocardiographic features
  61. A method to determine the kink resistance of stents and stent delivery systems according to international standards
  62. Comparison of stented bifurcation and straight vessel 3D-simulation with a prior simulated velocity profile inlet
  63. Transient Euler-Lagrange/DEM simulation of stent thrombosis
  64. Automated control of the laser welding process of heart valve scaffolds
  65. Automation of a test bench for accessing the bendability of electrospun vascular grafts
  66. Influence of storage conditions on the release of growth factors in platelet-rich blood derivatives
  67. Cryopreservation of cells using defined serum-free cryoprotective agents
  68. New bioreactor vessel for tissue engineering of human nasal septal chondrocytes
  69. Determination of the membrane hydraulic permeability of MSCs
  70. Climate retainment in carbon dioxide incubators
  71. Multiple factors influencing OR ventilation system effectiveness
  72. Evaluation of an app-based stress protocol
  73. Medication process in Styrian hospitals
  74. Control tower to surgical theater
  75. Development of a skull phantom for the assessment of implant X-ray visibility
  76. Surgical navigation with QR codes
  77. Investigation of the pressure gradient of embolic protection devices
  78. Computer assistance in femoral derotation osteotomy: a bottom-up approach
  79. Automatic depth scanning system for 3D infrared thermography
  80. A service for monitoring the quality of intraoperative cone beam CT images
  81. Resectoscope with an easy to use twist mechanism for improved handling
  82. In vitro simulation of distribution processes following intramuscular injection
  83. Adjusting inkjet printhead parameters to deposit drugs into micro-sized reservoirs
  84. A flexible standalone system with integrated sensor feedback for multi-pad electrode FES of the hand
  85. Smart control for functional electrical stimulation with optimal pulse intensity
  86. Tactile display on the remaining hand for unilateral hand amputees
  87. Effects of sustained electrical stimulation on spasticity assessed by the pendulum test
  88. An improved tracking framework for ultrasound probe localization in image-guided radiosurgery
  89. Improvement of a subviral particle tracker by the use of a LAP-Kalman-algorithm
  90. Learning discriminative classification models for grading anal intraepithelial neoplasia
  91. Regularization of EIT reconstruction based on multi-scales wavelet transforms
  92. Assessing MRI susceptibility artefact through an indicator of image distortion
  93. EyeGuidance – a computer controlled system to guide eye movements
  94. A framework for feedback-based segmentation of 3D image stacks
  95. Doppler optical coherence tomography as a promising tool for detecting fluid in the human middle ear
  96. 3D Local in vivo Environment (LivE) imaging for single cell protein analysis of bone tissue
  97. Inside-Out access strategy using new trans-vascular catheter approach
  98. US/MRI fusion with new optical tracking and marker approach for interventional procedures inside the MRI suite
  99. Impact of different registration methods in MEG source analysis
  100. 3D segmentation of thyroid ultrasound images using active contours
  101. Designing a compact MRI motion phantom
  102. Cerebral cortex classification by conditional random fields applied to intraoperative thermal imaging
  103. Classification of indirect immunofluorescence images using thresholded local binary count features
  104. Analysis of muscle fatigue conditions using time-frequency images and GLCM features
  105. Numerical evaluation of image parameters of ETR-1
  106. Fabrication of a compliant phantom of the human aortic arch for use in Particle Image Velocimetry (PIV) experimentation
  107. Effect of the number of electrodes on the reconstructed lung shape in electrical impedance tomography
  108. Hardware dependencies of GPU-accelerated beamformer performances for microwave breast cancer detection
  109. Computer assisted assessment of progressing osteoradionecrosis of the jaw for clinical diagnosis and treatment
  110. Evaluation of reconstruction parameters of electrical impedance tomography on aorta detection during saline bolus injection
  111. Evaluation of open-source software for the lung segmentation
  112. Automatic determination of lung features of CF patients in CT scans
  113. Image analysis of self-organized multicellular patterns
  114. Effect of key parameters on synthesis of superparamagnetic nanoparticles (SPIONs)
  115. Radiopacity assessment of neurovascular implants
  116. Development of a desiccant based dielectric for monitoring humidity conditions in miniaturized hermetic implantable packages
  117. Development of an artifact-free aneurysm clip
  118. Enhancing the regeneration of bone defects by alkalizing the peri-implant zone – an in vitro approach
  119. Rapid prototyping of replica knee implants for in vitro testing
  120. Protecting ultra- and hyperhydrophilic implant surfaces in dry state from loss of wettability
  121. Advanced wettability analysis of implant surfaces
  122. Patient-specific hip prostheses designed by surgeons
  123. Plasma treatment on novel carbon fiber reinforced PEEK cages to enhance bioactivity
  124. Wear of a total intervertebral disc prosthesis
  125. Digital health and digital biomarkers – enabling value chains on health data
  126. Usability in the lifecycle of medical software development
  127. Influence of different test gases in a non-destructive 100% quality control system for medical devices
  128. Device development guided by user satisfaction survey on auricular vagus nerve stimulation
  129. Empirical assessment of the time course of innovation in biomedical engineering: first results of a comparative approach
  130. Effect of left atrial hypertrophy on P-wave morphology in a computational model
  131. Simulation of intracardiac electrograms around acute ablation lesions
  132. Parametrization of activation based cardiac electrophysiology models using bidomain model simulations
  133. Assessment of nasal resistance using computational fluid dynamics
  134. Resistance in a non-linear autoregressive model of pulmonary mechanics
  135. Inspiratory and expiratory elastance in a non-linear autoregressive model of pulmonary mechanics
  136. Determination of regional lung function in cystic fibrosis using electrical impedance tomography
  137. Development of parietal bone surrogates for parietal graft lift training
  138. Numerical simulation of mechanically stimulated bone remodelling
  139. Conversion of engineering stresses to Cauchy stresses in tensile and compression tests of thermoplastic polymers
  140. Numerical examinations of simplified spondylodesis models concerning energy absorption in magnetic resonance imaging
  141. Principle study on the signal connection at transabdominal fetal pulse oximetry
  142. Influence of Siluron® insertion on model drug distribution in the simulated vitreous body
  143. Evaluating different approaches to identify a three parameter gas exchange model
  144. Effects of fibrosis on the extracellular potential based on 3D reconstructions from histological sections of heart tissue
  145. From imaging to hemodynamics – how reconstruction kernels influence the blood flow predictions in intracranial aneurysms
  146. Flow optimised design of a novel point-of-care diagnostic device for the detection of disease specific biomarkers
  147. Improved FPGA controlled artificial vascular system for plethysmographic measurements
  148. Minimally spaced electrode positions for multi-functional chest sensors: ECG and respiratory signal estimation
  149. Automated detection of alveolar arches for nasoalveolar molding in cleft lip and palate treatment
  150. Control scheme selection in human-machine- interfaces by analysis of activity signals
  151. Event-based sampling for reducing communication load in realtime human motion analysis by wireless inertial sensor networks
  152. Automatic pairing of inertial sensors to lower limb segments – a plug-and-play approach
  153. Contactless respiratory monitoring system for magnetic resonance imaging applications using a laser range sensor
  154. Interactive monitoring system for visual respiratory biofeedback
  155. Development of a low-cost senor based aid for visually impaired people
  156. Patient assistive system for the shoulder joint
  157. A passive beating heart setup for interventional cardiology training
https://doi.org/10.1515/cdbme-2016-0150
Keywords for this article
artificial pulse wave; artificial tissue phantom; artificial vessel system; fetal pulse oximetry
Creative Commons
BY-NC-ND 4.0

Articles in the same Issue

  1. Synthesis and characterization of PIL/pNIPAAm hybrid hydrogels
  2. Novel blood protein based scaffolds for cardiovascular tissue engineering
  3. Cell adhesion and viability of human endothelial cells on electrospun polymer scaffolds
  4. Effects of heat treatment and welding process on superelastic behaviour and microstructure of micro electron beam welded NiTi
  5. Long-term stable modifications of silicone elastomer for improved hemocompatibility
  6. The effect of thermal treatment on the mechanical properties of PLLA tubular specimens
  7. Biocompatible wear-resistant thick ceramic coating
  8. Protection of active implant electronics with organosilicon open air plasma coating for plastic overmolding
  9. Examination of dielectric strength of thin Parylene C films under various conditions
  10. Open air plasma deposited antimicrobial SiOx/TiOx composite films for biomedical applications
  11. Systemic analysis about residual chloroform in PLLA films
  12. A macrophage model of osseointegration
  13. Towards in silico prognosis using big data
  14. Technical concept and evaluation of a novel shoulder simulator with adaptive muscle force generation and free motion
  15. Usability evaluation of a locomotor therapy device considering different strategies
  16. Hypoxia-on-a-chip
  17. Integration of a semi-automatic in-vitro RFA procedure into an experimental setup
  18. Fabrication of MEMS-based 3D-μECoG-MEAs
  19. High speed digital interfacing for a neural data acquisition system
  20. Bionic forceps for the handling of sensitive tissue
  21. Experimental studies on 3D printing of barium titanate ceramics for medical applications
  22. Patient specific root-analogue dental implants – additive manufacturing and finite element analysis
  23. 3D printing – a key technology for tailored biomedical cell culture lab ware
  24. 3D printing of hydrogels in a temperature controlled environment with high spatial resolution
  25. Biocompatibility of photopolymers for additive manufacturing
  26. Biochemical piezoresistive sensors based on pH- and glucose-sensitive hydrogels for medical applications
  27. Novel wireless measurement system of pressure dedicated to in vivo studies
  28. Portable auricular device for real-time swallow and chew detection
  29. Detection of miRNA using a surface plasmon resonance biosensor and antibody amplification
  30. Simulation and evaluation of stimulation scenarios for targeted vestibular nerve excitation
  31. Deep brain stimulation: increasing efficiency by alternative waveforms
  32. Prediction of immediately occurring microsleep events from brain electric signals
  33. Determining cardiac vagal threshold from short term heart rate complexity
  34. Classification of cardiac excitation patterns during atrial fibrillation
  35. An algorithm to automatically determine the cycle length coverage to identify rotational activity during atrial fibrillation – a simulation study
  36. Deriving respiration from high resolution 12-channel-ECG during cycling exercise
  37. Reducing of gradient induced artifacts on the ECG signal during MRI examinations using Wilcoxon filter
  38. Automatic detection and mapping of double potentials in intracardiac electrograms
  39. Modeling the pelvic region for non-invasive pelvic intraoperative neuromonitoring
  40. Postprocessing algorithm for automated analysis of pelvic intraoperative neuromonitoring signals
  41. Best practice: surgeon driven application in pelvic operations
  42. Vasomotor assessment by camera-based photoplethysmography
  43. Classification of morphologic changes in photoplethysmographic waveforms
  44. Novel computation of pulse transit time from multi-channel PPG signals by wavelet transform
  45. Efficient design of FIR filter based low-pass differentiators for biomedical signal processing
  46. Nonlinear causal influences assessed by mutual compression entropy
  47. Comparative study of methods for solving the correspondence problem in EMD applications
  48. fNIRS for future use in auditory diagnostics
  49. Semi-automated detection of fractional shortening in zebrafish embryo heart videos
  50. Blood pressure measurement on the cheek
  51. Derivation of the respiratory rate from directly and indirectly measured respiratory signals using autocorrelation
  52. Left cardiac atrioventricular delay and inter-ventricular delay in cardiac resynchronization therapy responder and non-responder
  53. An automatic systolic peak detector of blood pressure waveforms using 4th order cumulants
  54. Real-time QRS detection using integrated variance for ECG gated cardiac MRI
  55. Preprocessing of unipolar signals acquired by a novel intracardiac mapping system
  56. In-vitro experiments to characterize ventricular electromechanics
  57. Continuous non-invasive monitoring of blood pressure in the operating room: a cuffless optical technology at the fingertip
  58. Application of microwave sensor technology in cardiovascular disease for plaque detection
  59. Artificial blood circulatory and special Ultrasound Doppler probes for detecting and sizing gaseous embolism
  60. Detection of microsleep events in a car driving simulation study using electrocardiographic features
  61. A method to determine the kink resistance of stents and stent delivery systems according to international standards
  62. Comparison of stented bifurcation and straight vessel 3D-simulation with a prior simulated velocity profile inlet
  63. Transient Euler-Lagrange/DEM simulation of stent thrombosis
  64. Automated control of the laser welding process of heart valve scaffolds
  65. Automation of a test bench for accessing the bendability of electrospun vascular grafts
  66. Influence of storage conditions on the release of growth factors in platelet-rich blood derivatives
  67. Cryopreservation of cells using defined serum-free cryoprotective agents
  68. New bioreactor vessel for tissue engineering of human nasal septal chondrocytes
  69. Determination of the membrane hydraulic permeability of MSCs
  70. Climate retainment in carbon dioxide incubators
  71. Multiple factors influencing OR ventilation system effectiveness
  72. Evaluation of an app-based stress protocol
  73. Medication process in Styrian hospitals
  74. Control tower to surgical theater
  75. Development of a skull phantom for the assessment of implant X-ray visibility
  76. Surgical navigation with QR codes
  77. Investigation of the pressure gradient of embolic protection devices
  78. Computer assistance in femoral derotation osteotomy: a bottom-up approach
  79. Automatic depth scanning system for 3D infrared thermography
  80. A service for monitoring the quality of intraoperative cone beam CT images
  81. Resectoscope with an easy to use twist mechanism for improved handling
  82. In vitro simulation of distribution processes following intramuscular injection
  83. Adjusting inkjet printhead parameters to deposit drugs into micro-sized reservoirs
  84. A flexible standalone system with integrated sensor feedback for multi-pad electrode FES of the hand
  85. Smart control for functional electrical stimulation with optimal pulse intensity
  86. Tactile display on the remaining hand for unilateral hand amputees
  87. Effects of sustained electrical stimulation on spasticity assessed by the pendulum test
  88. An improved tracking framework for ultrasound probe localization in image-guided radiosurgery
  89. Improvement of a subviral particle tracker by the use of a LAP-Kalman-algorithm
  90. Learning discriminative classification models for grading anal intraepithelial neoplasia
  91. Regularization of EIT reconstruction based on multi-scales wavelet transforms
  92. Assessing MRI susceptibility artefact through an indicator of image distortion
  93. EyeGuidance – a computer controlled system to guide eye movements
  94. A framework for feedback-based segmentation of 3D image stacks
  95. Doppler optical coherence tomography as a promising tool for detecting fluid in the human middle ear
  96. 3D Local in vivo Environment (LivE) imaging for single cell protein analysis of bone tissue
  97. Inside-Out access strategy using new trans-vascular catheter approach
  98. US/MRI fusion with new optical tracking and marker approach for interventional procedures inside the MRI suite
  99. Impact of different registration methods in MEG source analysis
  100. 3D segmentation of thyroid ultrasound images using active contours
  101. Designing a compact MRI motion phantom
  102. Cerebral cortex classification by conditional random fields applied to intraoperative thermal imaging
  103. Classification of indirect immunofluorescence images using thresholded local binary count features
  104. Analysis of muscle fatigue conditions using time-frequency images and GLCM features
  105. Numerical evaluation of image parameters of ETR-1
  106. Fabrication of a compliant phantom of the human aortic arch for use in Particle Image Velocimetry (PIV) experimentation
  107. Effect of the number of electrodes on the reconstructed lung shape in electrical impedance tomography
  108. Hardware dependencies of GPU-accelerated beamformer performances for microwave breast cancer detection
  109. Computer assisted assessment of progressing osteoradionecrosis of the jaw for clinical diagnosis and treatment
  110. Evaluation of reconstruction parameters of electrical impedance tomography on aorta detection during saline bolus injection
  111. Evaluation of open-source software for the lung segmentation
  112. Automatic determination of lung features of CF patients in CT scans
  113. Image analysis of self-organized multicellular patterns
  114. Effect of key parameters on synthesis of superparamagnetic nanoparticles (SPIONs)
  115. Radiopacity assessment of neurovascular implants
  116. Development of a desiccant based dielectric for monitoring humidity conditions in miniaturized hermetic implantable packages
  117. Development of an artifact-free aneurysm clip
  118. Enhancing the regeneration of bone defects by alkalizing the peri-implant zone – an in vitro approach
  119. Rapid prototyping of replica knee implants for in vitro testing
  120. Protecting ultra- and hyperhydrophilic implant surfaces in dry state from loss of wettability
  121. Advanced wettability analysis of implant surfaces
  122. Patient-specific hip prostheses designed by surgeons
  123. Plasma treatment on novel carbon fiber reinforced PEEK cages to enhance bioactivity
  124. Wear of a total intervertebral disc prosthesis
  125. Digital health and digital biomarkers – enabling value chains on health data
  126. Usability in the lifecycle of medical software development
  127. Influence of different test gases in a non-destructive 100% quality control system for medical devices
  128. Device development guided by user satisfaction survey on auricular vagus nerve stimulation
  129. Empirical assessment of the time course of innovation in biomedical engineering: first results of a comparative approach
  130. Effect of left atrial hypertrophy on P-wave morphology in a computational model
  131. Simulation of intracardiac electrograms around acute ablation lesions
  132. Parametrization of activation based cardiac electrophysiology models using bidomain model simulations
  133. Assessment of nasal resistance using computational fluid dynamics
  134. Resistance in a non-linear autoregressive model of pulmonary mechanics
  135. Inspiratory and expiratory elastance in a non-linear autoregressive model of pulmonary mechanics
  136. Determination of regional lung function in cystic fibrosis using electrical impedance tomography
  137. Development of parietal bone surrogates for parietal graft lift training
  138. Numerical simulation of mechanically stimulated bone remodelling
  139. Conversion of engineering stresses to Cauchy stresses in tensile and compression tests of thermoplastic polymers
  140. Numerical examinations of simplified spondylodesis models concerning energy absorption in magnetic resonance imaging
  141. Principle study on the signal connection at transabdominal fetal pulse oximetry
  142. Influence of Siluron® insertion on model drug distribution in the simulated vitreous body
  143. Evaluating different approaches to identify a three parameter gas exchange model
  144. Effects of fibrosis on the extracellular potential based on 3D reconstructions from histological sections of heart tissue
  145. From imaging to hemodynamics – how reconstruction kernels influence the blood flow predictions in intracranial aneurysms
  146. Flow optimised design of a novel point-of-care diagnostic device for the detection of disease specific biomarkers
  147. Improved FPGA controlled artificial vascular system for plethysmographic measurements
  148. Minimally spaced electrode positions for multi-functional chest sensors: ECG and respiratory signal estimation
  149. Automated detection of alveolar arches for nasoalveolar molding in cleft lip and palate treatment
  150. Control scheme selection in human-machine- interfaces by analysis of activity signals
  151. Event-based sampling for reducing communication load in realtime human motion analysis by wireless inertial sensor networks
  152. Automatic pairing of inertial sensors to lower limb segments – a plug-and-play approach
  153. Contactless respiratory monitoring system for magnetic resonance imaging applications using a laser range sensor
  154. Interactive monitoring system for visual respiratory biofeedback
  155. Development of a low-cost senor based aid for visually impaired people
  156. Patient assistive system for the shoulder joint
  157. A passive beating heart setup for interventional cardiology training
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2025 De Gruyter Brill
Downloaded on 13.9.2025 from https://www.degruyterbrill.com/document/doi/10.1515/cdbme-2016-0150/html
Scroll to top button