Jahr Name
2022

Simulation framework for reflective PPG signal analysis depending on sensor placement and wavelength

M. Reiser, A. Breidenassel, O. Amft

IEEE-EMBS International Conference on Wearable and Implantable Body Sensor Networks, 27. – 30. September 2022, Ioannina, Griechenland

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We analyse the influence of reflective photoplethysmography (PPG) sensor positioning relative to blood vessels. A voxel based Monte Carlo simulation framework was developed and validated to simulate photon-tissue interactions. An anatomical model comprising a multi-layer skin description with a blood vessel is presented to simulate PPG sensor positioning at the volar wrist. The simulation framework was validated against standard test cases reported in literature. The blood vessel was considered in regular and dilated states. Simulations were performed with 10 8 photon packets and repeated five times for each condition, including wavelength, relative position of PPG sensor and vessel, and vessel dilation state. Statistical weights were associated to photon packets to represent absorption and scattering effects. A symmetrical arrangement of the PPG sensor around the blood vessel showed the maximum AC …

 

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2022

Proximity-based Eating Event Detection in Smart Eyeglasses with Expert and Data Models

A. Saphala, R. Zhang, O. Amft

ACM International Symposium on Wearable Computers, 11. – 15. September 2022, Atlanta & Cambridge, USA

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We compare performances of an expert model-based approach and a data-based baseline for eating event detection using proximity sensor data of smart eyeglasses. Proximity sensors in smart eyeglasses can provide dynamic distance estimates of cyclic temporalis muscle contraction during chewing without skin contact. Our expert model is based on proximity signal preprocessing and two-threshold grid search. In contrast, baseline data models were based on One-class Support-Vector-Machines. We evaluate both models with in-lab and free-living data from 15 participants. Free-living data were obtained across one day of wearing smart eyeglasses with temple-integrated proximity sensors in unconstrained settings. Overall, the retrieval performance F1 score of the two-threshold-based algorithm for free-living data ranged between 0.6 and 0.7, and outperformed all tested SVM model configurations. While SVM …

 

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2022

Non-contact temporalis muscle monitoring to detect eating in free-living using smart eyeglasses

A. Saphala, R. Zhang, T. Nam Thái, O. Amft

IEEE-EMBS International Conference on Wearable and Implantable Body Sensor Networks, 27. – 30. September 2022, Ioannina, Griechenland

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We investigate non-contact sensing of temporalis muscle contraction in smart eyeglasses frames to detect eating activity. Our approach is based on infra-red proximity sensors that were integrated into sleek eyeglasses frame temples. The proximity sensors capture distance variations between frame temple and skin at the frontal, hair-free section of the temporal head region. To analyse distance variations during chewing and other activities, we initially perform an in-lab study, where proximity signals and Electromyography (EMG) readings were simultaneously recorded while eating foods with varying texture and hardness. Subsequently, we performed a free-living study with 15 participants wearing integrated, fully functional 3Dprinted eyeglasses frames, including proximity sensors, processing, storage, and battery, for an average recording duration of 8.3hours per participant. We propose a new chewing sequence …

 

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2022

Feasibility And Acceptability Of Wearable Sensor Placement For Young Children.: 744

E. A Willis, D. Hales, F. Smith, R. Burney, M. C Rzepka, O. Amft, R. Barr, K. R Evenson, M. R Kosorok, D. S Ward

Proceedings of the: Feasibility And Acceptability Of Wearable Sensor Placement For Young Children.: 744

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PURPOSE: To examine parent perceptions of young children’s acceptability of different methods for wearable sensor placement and the feasibility of a free-living 3 to 7-day wear protocol.
METHODS: This study was conducted in three phases. During phase 1, parents of 3 to 8-year-old children (n= 105) and child care providers (n= 56) completed an online survey to rate aspects of fitting and likelihood of wear for 7 methods (headband, eyeglasses, skin adhesive patch, shirt clip/badge, mask, necklace, vest). During phase 2, parent/child (3-8 years old) dyads (n= 30) were asked to wear one of the top 5 prototypes of each wearable for three days (n= 6 children per method; no active sensor). During phase 3, parent/child (3-8 years old) dyads (n= 22) were recruited to wear prototypes of the top 3 wearables (from phase 2; n=~ 7 children per method; no active sensor) for 7 days. In phases 2 and 3, parents completed wear …

 

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2022

The Quest towards Automated Dietary Monitoring & Intervention in Free-living

O. Amft

International Workshop on Multimedia Assisted Dietary Management, 10. Oktober 2022, Lisbon, Portugal

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In the first part of this talk, I will review the hunt for sensors that started of the field of automated dietary monitoring (ADM) and continues to play a role in shaping current research. Moreover, I will describe the eyeglasses-based sensors that we currently develop and their perspectives for free-living monitoring. Moving on, in part two, I will discuss digital twin-based co-simulation as a novel system design approach for wearable devices and their relevance for supporting machine learning algorithm development. Finally, in part three, I will extend the scope into technology-based dietary intervention, i.e., how ADM can support users in their daily life when targeting a diet change or body weight reduction. I will show examples from our work to create digital twins that model individual behavior, identify behavior changes, and interaction strategies to integrate in everyday life.

 

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2022

IMUAngle: Joint Angle Estimation with Inertial Sensors in Daily Activities

L. Uhlenberg, S. Hassan Gangaraju, O. Amft

ACM International Symposium on Wearable Computers, 11.09. – 15.09.2022, Atlanta & Cambridge, USA

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We present a framework for IMU-based joint angle estimation during activities of daily living (ADL). Personalised musculoskeletal models were created from anthropometric data. Three sensor fusion algorithms were optimised to estimate orientation from IMU data and used as input for the simulation framework. Four ADLs, involving upper and lower limbs were simulated. Joint kinematics of IMU-based simulations were compared to optical marker-based simulations. Results for IMU-based simulations showed median RMSE of 0.8 − 15.5 ° for lower limbs and 1.5 − 33.9 ° for upper limbs. Median RMSE were 4.4 °, 5.8 °, 6.9 °, 6.5 ° for ankle plantarflexion, knee-, hip flexion, and hip rotation, respectively. For upper limbs, elbow flexion showed best median RMSE  ∼ 3.7 °, whereas elevation angles (∼ 24.5 °) and shoulder rotation (∼ 12.5 °) performed worst. Increased RMSE at upper limbs was attributed to the degrees of freedom at the shoulder region compared to the hip. Overall, transversal plane movements (rotations) showed higher median RMSE compared to sagittal plane movements  (flexion/extension). Optimisation of orientation estimators improved performance considerably depending on ADL (up to ∼ 20 °). Comparing sensor fusion algorithms, Madgwick and Mahony produced comparable joint kinematics, whereas the Extended Kalman Filter performance showed larger variability depending on the ADL. Our approach offers a realistic representation of joint kinematics and can be supported by optimising parameters of sensor fusion algorithms.

 

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2022

Reflecting on Approaches to Monitor User’s Dietary Intake

J. Keppel, U. Gruenefeld, M. Strauss, L. Ignacio Lopera Gonzalez, O. Amft, S. Schneegass

ACM International Conference on Mobile Human-Computer Interaction, 28.09. – 01.10.2022, Vancouver, Kanada

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Monitoring dietary intake is essential to providing user feedback and achieving a healthier lifestyle. In the past, different approaches for monitoring dietary behavior have been proposed. In this position paper, we first present an overview of the state-of-the-art techniques grouped by image-and sensor-based approaches. After that, we introduce a case study in which we present a Wizard-of-Oz approach as an alternative and non-automatic monitoring method.

 

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2022

Comparison of Surface Models and Skeletal Models for Inertial Sensor Data Synthesis

L. Uhlenberg, O. Amft

IEEE-EMBS International Conference on Wearable and Implantable Body Sensor Networks, 27. – 30. September 2022, Ioannina, Griechenland

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We present a modelling and simulation framework to synthesise body-worn inertial sensor data based on personalised human body surface and biomechanical models. Anthropometric data and reference images were used to create personalised body surface mesh models. The mesh armature was aligned using motion capture reference pose and afterwards mesh and armature were parented. In addition, skeletal models were created using an established musculoskeletal dynamic modelling framework. Four activities of daily living (ADL), including upper and lower limbs were simulated with surface and skeletal models using motion capture data as stimuli. Acceleration and angular velocity data were simulated for 12 body areas of surface models and 8 body areas of skeletal models. We compared simulated inertial sensor data of both models against physical IMU measurements that were obtained simultaneously …

 

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2023

Review on Excess Noise Measurements of Resistors

Daniela Walter, André Bülau and André Zimmermann

MDPI Sensors MDPI Sensors

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Increasing demands for precision electronics require individual components such as resistors
to be specified, as they can be the limiting factor within a circuit. To specify quality and longterm
stability of resistors, noise measurements are a common method. This review briefly explains
the theoretical background, introduces the noise index and provides an insight on how this index
can be compared to other existing parameters.

2022

Untersuchungen zu flüssigkeitsbasierten, kapazitiven Neigungswinkelsensoren

Adrian Schwenck

OPUS - Online Publikationen der Universität Stuttgart

2022

European Digital Innovation Hubs & their activities for SMEs

Rainer Günzler

Smart Systems Integration 2022, 26. – 28. April, Grenoble, Frankreich

2022

Effective MEMS Manufacturing Using Vapor HF Etch Processing Illustrated by Means of a Sterilization Cycle Counter

N. Baum, R. Vora, G. Endress, I. Spies, D. Hoffmann, H. Trautner, C. Blattert, A. Dehé, D. Anderson, T. O‘Hara

9. GMM Fachtagung Mikro-Nano-Integration, 21. – 22. November 2022, Aachen

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In the aftermath of COVID-19 and with an increased awareness of health issues, the use of precisely targeted technological
methodologies for the solution of specific healthcare problems is becoming increasing important in medical applications. The use of MEMS technology for the development of an efficient sterilisation cycle counter by Hahn-Schickard is a simple but very effective example of such an application. Surface micromachining is applied utilizing vapor HF (vHF) etching and subsequent polymer anti-stiction coating as an efficient technique to remove sacrificial buried oxide layers and to release micro structure without stiction. The vHF etching process has been optimized and reaches etch rates of 900 nm/min for the buried oxide with a uniformity of more than 95 % across a 100 mm wafer.

 

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2022

Lichtqualität rauf, Stromverbrauch runter. Neuartige HCL-Steuerung

D. Schillinger, M. Kunzer, T. Hehn, N. Wörner

Markt & Technik Nr. 12/2022, 26-28


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2022

Novel Fabrication Technology for Thermoelectric Infrared Sensors Using Surface Micromachining

P. Raimann, S. Billat, I. Spies, J. Dietrich, D. Hoffmann, S. Keller, A. Dehé

Smart Systems Integration, 27.-28. April 2022, Grenoble, Frankreich

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In this paper a novel fabrication technology for thermoelectric infrared sensors is presented. For the first time, the thermal insulation of the absorber structure is achieved by self-assembling multilayer thermocouples. After removal of a sacrificial oxide layer by vapor hydrogen fluoride (vHF) etching, the thermocouples lift off due to residual stress gradients. This provides the necessary distance between the absorber and the substrate. Compared to state-of-the-art sensors, this implementation does not require extensive bulk processing such as grinding and cavity etching to achieve a thermally isolated absorber structure. The deflection of the realized structures has shown high agreement with an analytical model which is also presented in this paper.

 

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2022

Intelligenter optischer Drehwinkelsensor (INOSENS)

J. Seybold

Abschlussbericht

2022

Digitaler Retrofit von Maschinen und Produktionsanlagen

Karl-Peter Fritz, Henning Strauß, Christoph Rathfelder, André Bülau, Daniel Gaida

ISSN: Vogel Fachuch 978-3-8343-3481-7


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2021

Autonomer mikromechanischer Sterilisationszyklenzähler (AuSter)

D. Hoffmann

Schlussbericht AuSter IGF-Vorhaben 20710BG

2021

Entwurf einer CMOS-integrierten, rauscharmen Stromausleseschaltung mit niedriger Eingangskapazität für die medizinische Diagnostik via biologischer Nanoporen

M. Amayreh, S. Elsaegh, N. Butz, M. Kuderer, Y. Manoli

MikroSystemTechnik Kongress 2021, 08.11.2021 - 10.11.2021, Stuttgart-Ludwigsburg, Deutschland


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2021

A Mechanism for Seamless Cryptographic Rekeying in Real-Time Communication Systems

H. Bühler, A. Walz, A. Sikora

2021 17th IEEE International Workshop on Factory Communication Systems (WFCS), 09.-11.06.2021, Linz, Austria

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Cryptographic protection of messages requires frequent updates of the symmetric cipher key used for encryption and decryption, respectively. Protocols of legacy IT security, like TLS, SSH, or MACsec implement rekeying under the assumption that, first, application data exchange is allowed to stall occasionally and, second, dedicated control messages to orchestrate the process can be exchanged. In real-time automation applications, the first is generally prohibitive, while the second may induce problematic traffic patterns on the network. We present a novel seamless rekeying approach, which can be embedded into cyclic application data exchanges. Although, being agnostic to the underlying real-time communication system, we developed a demonstrator emulating the widespread industrial Ethernet system PROFINET IO and successfully use this rekeying mechanism.

 

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2021

Delta-Kodierung zur Reduzierung der Datenrate in neuronalen Sonden mit In-Situ Delta-Sigma Analog-Digital-Wandler Front-End

D. Wendler, J. Koerber, D. De Dorigo, R. Willaredt, Y. Manoli

MikroSystemTechnik Kongress, 08.-10. November 2021, Ludwigsburg