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3. Assessment of skin impedance in radiofrequency therapy : a study utilizing unique electrode form for cutaneous Leishmaniasis treatment

Author

Häusler, Ian Caetano, Paparo, Davide, Fehr, Daniel, Hagen, Raphael, Velez Mestre, Marta Sofia, Bonmarin, Mathias, Häusler, Ian Caetano, Paparo, Davide, Fehr, Daniel, Hagen, Raphael, Velez Mestre, Marta Sofia, and Bonmarin, Mathias

Abstract

This study aims to investigate the impact of electrode shape and positioning on skin impedance measurements, with a focus on a specific radiofrequency therapy device developed in-house for treating cutaneous Leishmaniasis. The study involved 22 volunteers of mixed genders, whose skin impedance was measured in the frequency range of 1~MHz to 10~MHz using the device's uniquely shaped, dry-applied electrodes. Additional measurements were conducted to record skin moisture, surface temperature, and personal parameters of the subjects, which were later used in correlation analysis. While the resistivity values from this study were found to be in alignment with those reported in the existing literature, it is positioning of the electrodes that significantly impacted the skin impedance measurements. Correlations were identified between the skin moisture and average phase shift in facial and forearm measurements and between the average magnitude and phase shift depending on the measurement site. Furthermore, a correlation was observed between the Cole series resistances of the facial and forearm skin. The study does not find a significant influence of gender, age, skin color, ethnicity, or Body Mass Index on the impedance measurements within the tested frequency range. This research enhances our understanding of skin impedance measurements using unique electrode designs and contributes to refining the design of radiofrequency therapy systems.

Published
2024

5. SLM: Bridge the Thin Gap Between Speech and Text Foundation Models

Author

Wang, Mingqiu, primary, Han, Wei, additional, Shafran, Izhak, additional, Wu, Zelin, additional, Chiu, Chung-Cheng, additional, Cao, Yuan, additional, Chen, Nanxin, additional, Zhang, Yu, additional, Soltau, Hagen, additional, Rubenstein, Paul K., additional, Zilka, Lukas, additional, Yu, Dian, additional, Pundak, Golan, additional, Siddhartha, Nikhil, additional, Schalkwyk, Johan, additional, and Wu, Yonghui, additional

Published
2023
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22. Tuning Parameters in the Genetic Algorithm Optimization of Electrostatic Electron Lenses

Author

Hesam Mahmoudi Nezhad, N. (author), Ghaffarian Niasar, M. (author), Hagen, C.W. (author), Kruit, P. (author), Hesam Mahmoudi Nezhad, N. (author), Ghaffarian Niasar, M. (author), Hagen, C.W. (author), and Kruit, P. (author)

Abstract

The design of electrostatic electron lenses involves the choice of many geometrical parameters for the lens electrodes as well as the choice of voltages applied to the electrodes. The purpose of the design is to focus the electrons at a specific point and to minimize the aberrations of the lens. In a previous study, genetic algorithm optimization was introduced to aid the designer. For speeding up the electrostatic field calculations, new methods for analytical approximations of the field near the optical axis were introduced. In this paper, the influence of the main tuning parameters of the Genetic Algorithms is analyzed. The analysis is performed on a typical electrostatic lens systems including 6 electrodes. Different combinations of population sizes and number of generations are taken and the quality of the optimized lens system is compared. It is seen that within a constant computational effort (time or total number of system evaluations), a lower population size with a larger number of generations can achieve better results compared to having larger population size and fewer generations. The combination of Crossover Heuristic with Mutation Gaussian showed significantly better results compared to all other combinations of Mutations and Crossovers. Crossover Fraction is also evaluated to find the most suited values of this parameter., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., ImPhys/Hagen group, High Voltage Technology Group, ImPhys/Hoogenboom group

Published
2023
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23. Portable multi-wavelength fluorescence measurement device : empirical evaluation

Author

Hagen, Raphael, Fehr, Daniel, Spano, Fabrizio, Babity, Samuel, Brambilla, Davide, Bonmarin, Mathias, Hagen, Raphael, Fehr, Daniel, Spano, Fabrizio, Babity, Samuel, Brambilla, Davide, and Bonmarin, Mathias

Abstract

Monitoring-based preventive medicine relies heavily on minimal or noninvasive, portable, and cost-effective measurement solutions. In this study, we present a handheld multiwavelength fluorescence measurement system for detection of dermally injected fluorescent tracers. The circular detection area of the device is positioned on the sample containing the fluorescent marker. The marker is excited at regular intervals by a pulse of light. The optical output power is controlled by a laser diode driver, which receives direct feedback on the emitted light intensity from the monitor photodiode integrated into the laser diode package. An optical diffuser is located in front of each laser diode to ensure uniform illumination of the measurement area. Pulsed excitation of the fluorescent tracer allows alternate measurement of foreground and background light intensity. By subtracting the background from the foreground and using a switched-input photocurrent measurement technique, the measured photocurrent represents the actual light emission from the marker. The instrument has interchangeable modules that contain the excitation electronics and emission filter. These modules allow the instrument to be configured for a variety of different fluorescent markers. In vitro measurements show that the device is capable of performing fluorescence measurements for its intended use as a point-of-care device in preventive medicine.

Published
2023

25. Portable multi-wavelength fluorescence measurement device : empirical evaluation

Author

Raphael Hagen, Daniel Fehr, Fabrizio Spano, Samuel Babity, Davide Brambilla, and Mathias Bonmarin

Subjects
Multi-wavelength, Handheld, Fluorometer, Electrical and Electronic Engineering, Ratiometric fluorescent tattoo, Instrumentation, 620: Ingenieurwesen, Fluorescence meter, Portable
Abstract

Monitoring-based preventive medicine relies heavily on minimal or noninvasive, portable, and cost-effective measurement solutions. In this study, we present a handheld multiwavelength fluorescence measurement system for detection of dermally injected fluorescent tracers. The circular detection area of the device is positioned on the sample containing the fluorescent marker. The marker is excited at regular intervals by a pulse of light. The optical output power is controlled by a laser diode driver, which receives direct feedback on the emitted light intensity from the monitor photodiode integrated into the laser diode package. An optical diffuser is located in front of each laser diode to ensure uniform illumination of the measurement area. Pulsed excitation of the fluorescent tracer allows alternate measurement of foreground and background light intensity. By subtracting the background from the foreground and using a switched-input photocurrent measurement technique, the measured photocurrent represents the actual light emission from the marker. The instrument has interchangeable modules that contain the excitation electronics and emission filter. These modules allow the instrument to be configured for a variety of different fluorescent markers. In vitro measurements show that the device is capable of performing fluorescence measurements for its intended use as a point-of-care device in preventive medicine.

Published
2023

34. Software-defined LiFi - RF network for Industry 4.0 applications

Author

Paraskevopoulos, Anagnostis, primary, Schlosser, Michael, additional, Pluemakarapunya, Warunee, additional, Schulz, Dominic, additional, Hellwig, Peter, additional, Hohmann, Julian, additional, Bohge, Mathias, additional, Menzel, Thomas, additional, Woesner, Hagen, additional, and Jungnickel, Volker, additional

Published
2022
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35. CNN-Based Classification of Craniosynostosis Using 2D Distance Maps

Author

Matthias, Schaufelberger, Reinald Peter, Ktihle, Christian, Kaiser, Andreas, Wachter, Frederic, Weichel, Niclas, Hagen, Friedemann, Ringwald, Urs, Eisenmann, Christian, Freudlsperger, and Werner, Nahml

Subjects
Craniosynostoses, Humans, Infant, Neural Networks, Computer, Tomography, X-Ray Computed, Bone and Bones
Abstract

Craniosynostosis is a condition associated with the premature fusion of skull sutures affecting infants. 3D photogrammetric scans are a promising alternative to computed tomography scans in cases of single suture or nonsyndromic synostosis for diagnostic imaging, but oftentimes diagnosis is not automated and relies on additional cephalometric measure-ments and the experience of the surgeon. We propose an alternative representation of the infant's head shape created from 3D photogrammetric surface scans as 2D distance maps. Those 2D distance maps rely on ray casting to extract distances from a center point to the head surface, arranging them into a 2D image grid. We use the distance map for an original convolutional neural network (CNN)-based classification approach, which is evaluated on a publicly available synthetic dataset for benchmarking and also tested on clinical data. Qualitative differences of different head shapes can be ob-served in the distance maps. The CNN-based classifier achieves accuracies of 100 % on the publicly available synthetic dataset and 98.86 % on the clinical test set. Our distance map approach demonstrates the diagnostic value of 3D photogrammetry and the possibility of automatic, CNN-based diagnosis. Future steps include the improvement of the mapping method and testing the CNN on more pathologies.

Published
2022

37. Portable Multi-Wavelength Fluorescence Measurement Device

Author

Hagen, Raphael, Fehr, Daniel, Spano, Fabrizio, Brambilla, Davide, and Bonmarin, Mathias

Subjects
610.28: Biomedizin, Biomedizinische Technik
Abstract

​© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., Monitoring-based preventive medicine relies heavily on minimal or noninvasive, portable and cost-effective measurement solutions. This work presents a portable multi-wavelength fluorescence measurement system. The pinhole collimator, Fresnel focusing lens and PIN photo diode provide a cost-effective fluorescent light detection path. The with matte black filament 3D printed housing reduces unwanted reflections along the detection path. The integrated laser diode drivers ensure constant optical output power during operation. This is achieved by utilizing a laser diode package which incorporates both a laser and monitor diode. The monitor diode's output photocurrent is proportional to the optical output power, and thus provides, a feedback path for the driver. An optical diffuser is pre-mounted on each laser diode, providing a uniform illumination of the measurement area. The device adapts to a wide variety of fluorescent dyes by offering exchangeable laser diode modules and support of standard-sized optical thin film filters. The precision integrator transimpedance amplifier applies a switched-input photocurrent measurement technique that ensures the level of sensitivity required for clinical usage. Experimental validation indicates sensitivity in the pico-ampere range. Ex vivo and in vivo measurements, performed by the Faculty of Pharmacy at the Université de Montréal, confirm that the instrument matches its intended application.

Published
2022

41. CNN-Based Classification of Craniosynostosis Using 2D Distance Maps

Author

Schaufelberger, Matthias, primary, Ktihle, Reinald Peter, additional, Kaiser, Christian, additional, Wachter, Andreas, additional, Weichel, Frederic, additional, Hagen, Niclas, additional, Ringwald, Friedemann, additional, Eisenmann, Urs, additional, Freudlsperger, Christian, additional, and Nahml, Werner, additional

Published
2022
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