Fabian Braun

Fabian Braun
Centre Suisse d'Electronique et de Microtechnique | CSEM SA

PhD

About

74
Publications
18,372
Reads
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501
Citations

Publications

Publications (74)
Article
Full-text available
Optical fibres enable to design of new textile-based sensors for an unobtrusive, continuous, and long-term acquisition of photoplethysmography (PPG) signals. However, no research has been done about the accuracy of measuring blood oxygen saturation (SpO 2 ) and the feasibility of PPG-based blood pressure measurement. This proof-ofconcept study exam...
Conference Paper
Fetal electrocardiography (fECG) has gotten widespread interest in the last years as technology for fetal monitoring. Compared to cardiotocography (CTG), the current state of the art, it can be designed in smaller formfactor and is thus suited for long-term and unsupervised monitoring. In the present study we evaluated a wearable system which is ba...
Conference Paper
This work presents a method to minimize the inadvertent cutting of tissues in surgeries involving bone drilling. We present electrical impedance measurements as an assistive technology to image-guided surgery to achieve online guidance. Proposed concept is to identify and localize the landmarks via impedance measurements and then use this informati...
Chapter
This chapter gives an overview of medical imaging methods that are used for generation of pulmonary images and it assesses their suitability for implementation into wearable instruments. It focuses on the noninvasive radiation-free method of electrical impedance tomography (EIT) which exhibits a high potential for clinical use in a wearable design....
Chapter
In this chapter, we review recent developments of wearable and mobile sensor devices used for monitoring of the respiratory system. The chapter is organized by the organs assessed, starting with the lungs, moving to the airways, and then extending to respiration-related functions of the cardiovascular system. In this chapter, we will discover how p...
Conference Paper
Peripheral oxygen saturation (SpO2) plays a key role in diagnosing sleep apnea. It is mainly measured via transmission pulse oximetry at the fingertip, an approach less suited for long-term monitoring over several nights.In this study we tested a more patient-friendly solution via a reflectance pulse oximetry device. Having previously observed issu...
Article
Respiration is an important parameter in critical and pediatric care since its monitoring allows medical staff to detect many life-threatening diseases. One of the existing monitoring methods is based on remote photoplethysmography (rPPG). This technique consists of extracting a signal related to blood volume variations using a camera. This signal...
Chapter
This chapter is dedicated to a novel family of sensors used for cardiovascular monitoring. Based on the so-called photoplethysmographic technology, optical cardiovascular monitors open the door to the comfortable and continuous monitoring of health status during daily life. Either integrated within a wrist-worn device, an arm band, or a chest patch...
Article
Full-text available
Pulmonary hypertension is a hemodynamic disorder defined by an abnormal elevation of pulmonary artery pressure (PAP). Current options for measuring PAP are limited in clinical practice. The aim of this study was to evaluate if electrical impedance tomography (EIT), a radiation-free and non-invasive monitoring technique, can be used for the continuo...
Article
Full-text available
Previous animal experiments have suggested that electrical impedance tomography (EIT) has the ability to noninvasively track changes in cardiac stroke volume (SV). The present study intended to reproduce these findings in patients during a fluid challenge. In a prospective observational study including critically ill patients on mechanical ventilat...
Conference Paper
The state-of-the-art non-invasive measurement of peripheral oxygen saturation (SpO2) during sleep is mainly based on pulse oximetry at the fingertip. Although this approach is noninvasive, it can still be obtrusive and cumbersome to apply, in particular for ambulatory monitoring over several nights.We developed a wrist-worn reflectance pulse oximet...
Conference Paper
Atrial fibrillation (AF) affects millions of people worldwide and needs to be diagnosed in its early stage to provide proper treatment. However, the numerous wearable devices available today are not yet able to discriminate AF episodes from other cardiac arrhythmias and merely detect normal vs abnormal rhythms.In this study we investigated the perf...
Article
Full-text available
Current oxygen delivery modes lack monitoring and can be cumbersome for patients with chronic respiratory diseases. Integrating a pulse oximeter and nasal oxygen cannulas into eyeglasses would reduce the burden of current solutions. An ear pulse oximeter (OxyFrame) was evaluated on 16 healthy volunteers and 20 hypoxemic patients with chronic respir...
Article
Background: Intraoperative hypotension is associated with postoperative complications and death. Oscillometric brachial cuffs are used to measure arterial pressure (AP) in most surgical patients but may miss acute changes in AP. We hypothesized that pulse oximeter waveform analysis may help to detect changes in systolic AP (SAP) and mean AP (MAP)...
Article
Objective: Development of wearable medical technology for remote monitoring of patients suffering from chronic lung diseases may improve the care, therapy and outcome of these patients. Approach: A multimodal system using wearable sensors for the acquisition of multiple biosignals (electrical bioimpedance of the chest for electrical impedance to...
Chapter
Full-text available
Pulse wave analysis, or PWA, is a technique based on the morphological analysis of blood pressure waveforms, whose shape reflects crucial information on the properties of the arterial wall and blood pressure itself. Although the first historical developments of PWA date back to the nineteenth century, the technique started to prosper with the devel...
Article
Objective: In EIT applications to the thorax,a single electrode plane has typically been used to reconstruct a transverse 2D "slice".However, such images can be misleading as EITis sensitive to contrasts above and below the electrodeplane, and ventilation and aeration inhomogeneitiescan be distributed in complex ways.Using two (or more) electrode...
Data
Zip file containing documented Matlab and COMSOL files. The COMSOL and Matlab files used for the modelling aspects of the paper. A detailed “read me” document describing the individual Matlab files is also supplied. (ZIP)
Data
Supporting information to the article. Additional schematic explanations, initial isotopologue/isotopocule concentration calculation, final isotopic composition calculation, tables summarising parameters used for the simulations as well as a selection of simulation results and corresponding NSE and NME, experimental methods and results, and differe...
Article
Full-text available
Predicting the fate of chloroethenes in groundwater is essential when evaluating remediation strategies. Such predictions are expected to be more accurate when incorporating isotopic parameters. Although secondary chlorine isotope effects have been observed during reductive dechlorination of chloroethenes, development of modelling frameworks and si...
Article
This paper presents a wearable sensor architecture for frequency-multiplexed electrical impedance tomography (EIT) and synchronous multilead electrocardiogram (ECG) data acquisition. The system is based on a novel electronic sensing architecture, called cooperative sensors, that significantly reduces the cabling complexity and enables flexible EIT...
Conference Paper
Full-text available
Routine monitoring of blood pressure during general anesthesia relies on intermittent measurements with a non-invasive brachial cuff inflated every two to five minutes. While all these patients are equipped by a fingertip pulse oximeter, the acquired optical signals currently only provide SpO2 estimates. Our running clinical trial (NCT02651558) pre...
Conference Paper
Full-text available
Background and Goal of Study: Obtaining accurate continuous blood pressure (BP) monitoring is mandatory in critically-ill, anesthetized patients or during complex surgical procedures. The gold standard for continuous BP measurement invasive arterial catheter- is complex and associated with morbidity. To allow non-invasive beat-to-beat BP measuremen...
Conference Paper
Full-text available
Obtaining accurate continuous blood pressure monitoring is mandatory in critically-ill, anesthetized patients or during long and challenging surgical procedures. The gold standard for continuous BP measurement (invasive arterial catheter) is complex and associated with morbidity. This study presents a simple way to measure non-invasive BP continuo...
Conference Paper
Full-text available
While hypertension globally affects two out of five adults worldwide, there exists no easily-scalable technology to measure blood pressure out of the clinics. The idea of using smartphone sensors to estimate blood pressure was already tackled in the past, but failed because of low accuracy. Based on data from a previous study (NCT02651558), we rece...
Article
Full-text available
Cardiac output (CO) and stroke volume (SV) are parameters of key clinical interest. Many techniques exist to measure CO and SV, but are either invasive or insufficiently accurate in clinical settings. Electrical impedance tomography (EIT) has been suggested as a noninvasive measure of SV, but inconsistent results have been reported. Our goal is to...
Data
Temporal evolution of SVRef, heart rate and EIT-based features for subject S01. See caption of Fig 9 for details. (PDF)
Data
Temporal evolution of SVRef, heart rate and EIT-based features for subject S02. See caption of Fig 9 for details. (PDF)
Data
Temporal evolution of SVRef, heart rate and EIT-based features for subject S08. See caption of Fig 9 for details. (PDF)
Data
Temporal evolution of SVRef, heart rate and EIT-based features for subject S10. See caption of Fig 9 for details. (PDF)
Data
Absolute SV via subject-independent calibration on healthy volunteers. Subject-specific and overall performance for a selection of eight features (a) to (h) and hypothesis (H1) absolute SV via subject-independent calibration. The performance between SVEIT and SVRef is evaluated in terms of absolute error ϵAbs and correlation coefficient r. The (†)...
Data
Relative SV via subject-specific calibration on healthy volunteers. Subject-specific and overall performance for a selection of eight features (a) to (h) and hypothesis (H4) relative SV via subject-specific calibration. The performance between ΔSVEIT and ΔSVRef is evaluated in terms of angular error ϵα and angular concordance rate CR. The (†) indic...
Data
Temporal evolution of SVRef, heart rate and EIT-based features for subject S04. See caption of Fig 9 for details. (PDF)
Data
Temporal evolution of SVRef, heart rate and EIT-based features for subject S05. See caption of Fig 9 for details. (PDF)
Data
Absolute SV via subject-specific calibration on healthy volunteers. Subject-specific and overall performance for a selection of eight features (a) to (h) and hypothesis (H2) absolute SV via subject-specific calibration. The performance between SVEIT and SVRef is evaluated in terms of absolute error ϵAbs and correlation coefficient r. The (†) indica...
Data
Relative SV via subject-independent calibration on healthy volunteers. Subject-specific and overall performance for a selection of eight features (a) to (h) and hypothesis (H3) relative SV via subject-independent calibration. The performance between ΔSVEIT and ΔSVRef is evaluated in terms of angular error ϵα and angular concordance rate CR. The (†)...
Data
Video of ECG-gated 3D EIT for each subject. Sequence of images showing the cardiosynchronous conductivity change on the five image planes L1 (highest) to L5 (lowest) for the nine volunteers (a) to (i), in supine position. For each subject (i.e. each column) the images were scaled to an individual color scale and show the average of the last minute...
Data
Temporal evolution of SVRef, heart rate and EIT-based features for subject S06. See caption of Fig 9 for details. (PDF)
Data
Temporal evolution of SVRef, heart rate and EIT-based features for subject S09. See caption of Fig 9 for details. (PDF)
Thesis
Full-text available
In clinical practice it is of vital importance to track the health of a patient's cardiovascular system via the continuous measurement of hemodynamic parameters. Cardiac output (CO) and the related stroke volume (SV) are two such parameters of central interest as they are closely linked with oxygen delivery and the health of the heart. Many techniq...
Article
Objective : Electrical impedance tomography (EIT) shows potential for radiation-free and non-invasive hemodynamic monitoring. However, many factors degrade the accuracy and repeatability of these measurements. Our goal is to estimate the impact of this variability on EIT-based monitoring of two important central hemodynamic parameters: stroke volum...
Conference Paper
Full-text available
Cuffless blood pressure monitoring at the chest requires accurate detection of the arrival time of arterial pressure pulses at chest skin. A clinical trial was designed (NCT02651558) in order to assess the performance of single-and multi-channel reflective PPG sensors when no pressure is applied onto optical probe. Experimental setup involved invas...
Conference Paper
Full-text available
The terminology of cuffless Blood Pressure (BP) measuring techniques currently lacks an appropriate consensus, leading to repeated misunderstandings among researchers, clinicians and investors. Numerous techniques designed to measure BP in a continuous and cuffless manner have been disclosed in the past. However, most developments focus either on t...
Conference Paper
Full-text available
The performance of estimating Systolic Blood Pressure (SBP) in anesthetized patients via Pulse Arrival Time (PAT) techniques was studied with respect to the minimum required time in between two recalibration procedures. Materials: a clinical trial [NCT02651558] involving 14 patients was conducted measuring PAT from an ECG and an arterial line inser...
Conference Paper
Until today, vital signs monitoring in neonatal intensive care units (NICUs) is based on wired sensors, known to cause discomfort and false alarms. In view of overcoming such issues we investigate a contactless method for respiration monitoring by means of a simple video camera. Unlike many other solutions proposed in the literature, our approach m...
Article
[ J. R. Soc. Interface 14 , 20170060 (Published online 8 March 2017) ([doi:10.1098/rsif.2017.0060][2])][2] [Figure 2][2] is presented incorrectly in the published paper due to swapped curve denotations. The correct figure is shown below: ![Figure 2.][3] Figure 2. Attenuation spectrum from
Conference Paper
Full-text available
The potential of imaging photoplethysmography for cardiovascular monitoring applications has been demonstrated recently. Various processing schemes have been proposed to extract heart rate (HR) from a defined region of interest (ROI) on the face. However, the reasons that motivate the choice of the ROI are often unclear. This study aimed at investi...
Conference Paper
Full-text available
Imaging photoplethysmography (iPPG) has gained a lot of popularity as a contactless heart rate (HR) monitoring technique. However, most of the existing approaches to estimate HR are based on block-wise processing schemes, which are not optimal for real-time applications. The aim of this study was to investigate robust HR estimation methods having a...
Article
Knowledge of an individual's skin condition is important for pressure ulcer prevention. Detecting early changes in skin through perfusion, oxygen saturation values, and pressure on tissue and subsequent therapeutic intervention could increase patients' quality of life drastically. However, most existing sensing options create additional risk of ulc...
Article
Electrical impedance tomography (EIT) is an emerging technology for real-time monitoring of patients under mechanical ventilation. EIT has the potential to offer continuous medical monitoring while being non-invasive, radiation-free and low-cost. Due to their ill-posedness, image reconstruction typically uses regularization, which implies a hyperpa...
Article
We report on the production, characterization, and textile integration of polymer optical fibers (POF) to develop a flexible photonic sensor. Mono-component POFs were produced continuously by melt-extrusion. Advantageously for pressure sensing, the un-clad fibers are more susceptible to macro-bending. The fibers’ mechanical and optical properties a...
Article
Current monitoring modalities for patients with pulmonary hypertension (PH) are limited to invasive solutions. A novel approach for the non-invasive and unsupervised monitoring of pulmonary artery pressure (PAP) in patients with PH was proposed and investigated. The approach was based on the use of electrical impedance tomography (EIT), a non-invas...
Conference Paper
Full-text available
Routine monitoring of blood pressure during general anaesthesia relies on intermittent measurements with a non-invasive brachial cuff every five minutes. This manuscript provides first experimental evidence that a physiology-based pulse wave analysis algorithm applied to optical data (as provided by a standard fingertip pulse oximeter) is capable o...
Conference Paper
Full-text available
While elevated blood pressure affects one third of adults in developed countries, there is nowadays no comfortable and easy-to-deploy technology to assess blood pressure in daily life scenarios. The increasing use of smart devices has recently spread the availability of photoplethysmographic (PPG) sensors at everyone's wrist (smartwatches), or even...
Conference Paper
Full-text available
Current solutions for the monitoring of pulmonary artery pressure (PAP) in patients suffering from pulmonary hypertension are limited to invasive means. Non-invasive alternatives, such as Doppler echocardiography, are incompatible with continuous monitoring due to their dependency on qualified personnel to perform the measurements. In the present s...
Conference Paper
Pneumonia remains the worldwide leading cause of children mortality under the age of five, with every year 1.4 million deaths. Unfortunately, in low resource settings, very limited diagnostic support aids are provided to point-of-care practitioners. Current UNICEF/WHO case management algorithm relies on the use of a chronometer to manually count br...
Article
Monitoring of pulmonary artery pressure (PAP) in pulmonary hypertensive patients is currently limited to invasive solutions. We investigate a novel non-invasive approach for continuous monitoring of PAP, based on electrical impedance tomography (EIT), a safe, low-cost and non-invasive imaging technology. EIT recordings were performed in three healt...
Research
Full-text available
During the last 10 years CSEM has intensively worked on the development of an innovative catalog of technologies that enable the monitoring of blood pressure in a comfortable and continuous manner. Either located at the chest or the wrist, these technologies open the door to a new era of cuffless blood pressure monitoring: improving patient's comfo...
Article
Electrical impedance tomography (EIT) allows the measurement of intra-thoracic impedance changes related to cardiovascular activity. As a safe and low-cost imaging modality, EIT is an appealing candidate for non-invasive and continuous haemodynamic monitoring. EIT has recently been shown to allow the assessment of aortic blood pressure via the esti...
Article
Full-text available
Electrical impedance tomography (EIT) is a non-invasive imaging technique that can measure cardiac-related intra-thoracic impedance changes. EIT-based cardiac output estimation relies on the assumption that the amplitude of the impedance change in the ventricular region is representative of stroke volume (SV). However, other factors such as heart m...
Article
Cooperative sensors is a novel measurement architecture that allows the acquiring of biopotential signals on patients in a comfortable and easy-to-integrate manner. The novel sensors are defined as cooperative in the sense that at least two of them work in concert to measure a target physiological signal, such as a multi-lead electrocardiogram or a...
Article
Full-text available
Cardiac output is one of the most determining parameters to assess cardiac function and manage hemodynamically unstable patients. Its continuous and non-invasive estimation, however, remains a technical challenge. In that context, electrical impedance tomography (EIT), an emerging modality for a new class of safe and portable hemodynamic monitors,...
Article
Full-text available
Silicon photomultipliers are novel solid state photodetectors that recently became commercially available. The goal of this paper was to investigate their suitability for low light level detection in miniaturized functional near-infrared spectroscopy instruments. Two measurement modules with a footprint of 26×26 mm(2) were built, and the signal-to-...