Markus Lüken

Markus Lüken
RWTH Aachen University · Helmholtz Institute of Biomedical Engineering

Master of Science

About

34
Publications
3,036
Reads
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153
Citations
Citations since 2017
24 Research Items
145 Citations
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Publications

Publications (34)
Article
Full-text available
In today’s neonatal intensive care units, monitoring vital signs such as heart rate and respiration is fundamental for neonatal care. However, the attached sensors and electrodes restrict movement and can cause medical-adhesive-related skin injuries due to the immature skin of preterm infants, which may lead to serious complications. Thus, unobtrus...
Article
Full-text available
Introduction Aging is accompanied by changes in muscle mass, strength and loss of sensory, visual and auditive functions. However, these changes do not occur linearly, most spatiotemporal gait parameters change with aging. Age simulation suits have been invented to give young people an impression of the implications of being older and may be a usef...
Article
Full-text available
Lyapunov exponent is a promising parameter to ascertain the stability of the human gait. In this work, we use a time-series model based on a second-order delay-system with inertial measurement units placed on the foot and wrist. Stability is analyzed in a localized sense, with the Lyapunov exponent computed in the temporal region between two heel-s...
Conference Paper
In this work, we evaluated the possibility to use synthesized IMU data for training a deep neural network to generate a more complex, full-body description of the human gait in terms of joint angle trajectories from a sparse sensor setup. In this context, a sparse sensor setup consists of a few sensors attached to human body segments in an unobtrus...
Conference Paper
Gait behavior is considered an important indicator for the assessment of the general health status and provides a diagnostic observation for neuro-degenerative and musculo-skeletal diseases. Individual changes in gait behavior often reflect a deterioration of the current health status in a general sense and therefore provide significant information...
Conference Paper
Step Length is an important metric that can be used for the analysis and assessment of the gait. Proper dynamical models are not available in current literature associated with the wrist that can adequately determine the step length using recursive estimation techniques. This study presents a method to estimate the step length using angular velocit...
Article
The determination of step length, an important gait parameter, has been a challenging task. Although unobtrusive sensors (inertial measurement units) have been developed recently, they cannot facilitate the automatic estimation of step length. In this article, we use a model-based technique to determine the step length using the Unscented Kalman Fi...
Chapter
In this work, we present an approach for non-contact automatic extraction of respiration in infants using infrared thermography video sequences, which were recorded in a neonatal intensive care unit. The respiratory signal was extracted in real-time on low-cost embedded GPUs by analyzing breathing-related temperature fluctuations in the nasal regio...
Article
Full-text available
The detection of muscle contraction and the estimation of muscle force are essential tasks in robot-assisted rehabilitation systems. The most commonly used method to investigate muscle contraction is surface electromyography (EMG), which, however, shows considerable disadvantages in predicting the muscle force, since unpredictable factors may influ...
Article
Full-text available
Premature infants are among the most vulnerable patients in a hospital. Due to numerous complications associated with immaturity, a continuous monitoring of vital signs with a high sensitivity and accuracy is required. Today, wired sensors are attached to the patient’s skin. However, adhesive electrodes can be potentially harmful as they can damage...
Article
Capacitive electrocardiogram (cECG) has been proposed for various applications to extend cardiac monitoring to everyday life. While offering unobtrusive measurement of an electrocardiogram, cECG measurements experience severe motion artifacts with higher amplitudes and longer durations, which results in gaps in the signal availability and deteriora...
Article
Full-text available
The step length is an important parameter in gait analysis. Long-term monitoring applications for gait analysis are often based on inertial measurement units (IMUs) due to their low-cost and unobtrusive nature. Spatial gait parameters, such as step or stride length, are therefore not directly accessible. In this contribution, we focus on model-base...
Chapter
Monitoring a patient's vital signs daily is of increasing interest to handle the economic challenges in our health-care systems. Comfort, ease of use, and reliability of these systems are necessary for the patient's compliance. Therefore, wearable or textile-integrated sensors are desirable. Unobtrusive measurement techniques are preferred by the p...
Article
Full-text available
Body sensor networks (BSNs) represent an important research tool for exploring novel diagnostic or therapeutic approaches. They allow for integrating different measurement techniques into body-worn sensors organized in a network structure. In 2011, the first Integrated Posture and Activity Network by MedIT Aachen (IPANEMA) was introduced. In this w...
Article
Stride time variability is an important indicator for the assessment of gait stability. An accurate extraction of the stride intervals is essential for determining stride time variability. Peak detection is a commonly used method for gait segmentation and stride time estimation. Standard peak detection algorithms often fail due to additional moveme...
Research
Observation of the human knee stiffness is known to be an important issue in rehabilitation robotics in order to consider biomechanical knee parameters of the individual patient. As in-vivo identification often is a complicated task, modeling of biomechanical processes always comes with uncertainties. Therefore, we present a new model-based estimat...
Article
Full-text available
We address the estimation of biomechanical parameters with wearable measurement technologies. In particular, we focus on the estimation of sagittal plane ankle joint stiffness in dorsiflexion/plantar flexion. For this estimation, a novel nonlinear biomechanical model of the lower leg was formulated that is driven by electromyographic signals. The m...
Article
Full-text available
Electrical impedance tomography (EIT) provides global and regional information about ventilation by means of relative changes in electrical impedance measured with electrodes placed around the thorax. In combination with lung function tests, e.g. spirometry and body plethysmography, regional information about lung ventilation can be achieved. Imped...
Conference Paper
Für die Regelung eines Exoskeletts oder einer aktiven Or-these ist es wichtig, dass eine ausreichend genaue Model-lierung von Last (Mensch) und Exoskelett vorliegt. Die un-terstützenden Aktoren müssen nicht nur gegen die Trägheitoder Schwerkraft arbeiten, sondern unter Umständen auchgegen Kräfte, die vom Nutzer aufgebracht werden. EineMöglichkeit,...
Conference Paper
Observation of the human knee stiffness is known to be an important issue in rehabilitation robotics in order to consider biomechanical knee parameters of the individual patient. As in-vivo identification often is a complicated task, modeling of biomechanical processes always comes with uncertainties. Therefore, we present a new model-based estimat...
Article
Objective: We consider the problem of stiffness estimation for the human knee joint during motion in the saggital plane. Methods: The new stiffness estimator uses a nonlinear reduced-order biomechanical model and a body sensor network (BSN). The developed model is based on a two-dimensional knee kinematics approach to calculate the angle-depende...
Article
Observation of the human knee stiffness is known to be an important issue in rehabilitation robotics in order to consider biomechanical knee parameters of the individual patient. As in-vivo identification often is a complicated task, modeling of biomechanical processes always comes with uncertainties. Therefore, we present a new model-based estimat...
Article
Full-text available
We present a new calibration procedure for low-cost nine degrees-of-freedom (9DOF) magnetic, angular rate and gravity (MARG) sensor systems, which relies on a calibration cube, a reference table and a body sensor network (BSN). The 9DOF MARG sensor is part of our recently-developed "Integrated Posture and Activity Network by Medit Aachen" (IPANEMA)...
Article
Spasticity is a common disorder of the skeletal muscle with a high incidence in industrialised countries. A quantitative measure of spasticity using body-worn sensors is important in order to assess rehabilitative motor training and to adjust the rehabilitative therapy accordingly. We present a new approach to spasticity detection using the Integra...
Article
Spasticity is a common disorder of the skeletal muscle with a high incidence in industrialised countries, occurring for example after multiple sclerosis or stroke and is associated with brain or spinal cord damage. A quantitative measure of spasticity using body-worn sensors is desirable in order to assess rehabilitative motor training and prevent...

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