Feature-based differentiation of malignant melanomas, lesions and healthy skin in multiphoton tomography skin images. - In: Current directions in biomedical engineering, ISSN 2364-5504, Bd. 8 (2022), 2, S. 45-48
https://doi.org/10.1515/cdbme-2022-1013
Evaluation of spatio-temporal electrocutaneous warning signals. - In: Current directions in biomedical engineering, ISSN 2364-5504, Bd. 8 (2022), 2, S. 313-316
Acoustic or visual warning signals for workers in hazardous situations might fail under loud and/or lowvisibility work situations. A warning system that uses electrocutaneous stimulation can overcome this problem. The aim of this pilot study was to find spatio-temporal stimulation patterns for appropriate electrical warning. Eight electrode pairs were attached to the upper right arm of 16 participants. The stimulation was conducted with bi-phasic rectangular pulses of 150 μs and an amplitude of up to 25 mA. Pulse intervals that generate a single pulse, pulsating, vibrating, and continuous perception as well as varying spatial patterns (e.g. alternating between electrode pairs or circumferentially around the arm) were investigated and evaluated with regard to alertness, discomfort, and urgency. The pilot study revealed that a stimulation signal that generates a vibrating perception and is applied as a circumferential signal around the arm showed the highest values of alertness and is therefore considered a potential warning pattern for future studies with larger study groups.
https://doi.org/10.1515/cdbme-2022-1080
Bad channel detection in EEG recordings. - In: Current directions in biomedical engineering, ISSN 2364-5504, Bd. 8 (2022), 2, S. 257-260
Electroencephalography (EEG) is widely used in clinical applications and basic research. Dry EEG opened the application area to new fields like self-application during gaming and neurofeedback. While recording, the signals are always affected by artefacts. Manual detection of bad channels is the gold standard in both gel-based and dry EEG but is timeconsuming. We propose a simple and robust method for automatic bad channel detection in EEG. Our method is based on the iterative calculation of standard deviations for each channel. Statistical measures of these standard deviations serve as indications for bad channel detection. We compare the new method to the results obtained from the manually identified bad channels for EEG recordings. We analysed EEG signals during resting state with eyes closed and datasets with head movement. The results showed an accuracy of 99.69 % for both gel-based and dry EEG for resting state EEG. The accuracy of our new method is 99.38 % for datasets with the head movement for both setups. There was no significant difference between the manual gold standard of bad channel identification and our iterative standard deviation method. Therefore, the proposed iterative standard deviation method can be used for bad channel detection in resting state and movement EEG recordings.
https://doi.org/10.1515/cdbme-2022-1066
Novel replaceable EEG electrode system. - In: Current directions in biomedical engineering, ISSN 2364-5504, Bd. 8 (2022), 2, S. 249-252
Due to the direct contact between electrode and scalp, dry EEG electrodes are exposed to increased mechanical wear compared to conventional gel-based electrodes. However, state-of-the-art commercial cap systems commonly use permanently fixated electrodes which can lead to downtime of the EEG cap during professional repair and replacement as well as reduced overall lifetime. An easily replaceable EEG electrode would furthermore improve hygiene, especially for newborn and infant applications. We propose a novel replaceable electrode system, consisting of an electrode holder, a snap top, a contact ring fixated inside the electrode holder, and a replaceable electrode. The production process consists of 3D printing, silicone molding, resin casting, and electroless plating. The replaceable electrode system is integrated into a multichannel EEG cap system. A verification study is conducted with 30 volunteers. The operators experienced that the new electrode holder eases adjustment of the electrode to have proper contact with the scalp. During the study, defective electrodes can be replaced without a soldering process. Furthermore, all electrodes stayed in the holder and did not fall off the cap for the whole session. In conclusion, the novel replaceable electrode system is suitable for EEG measurements.
https://doi.org/10.1515/cdbme-2022-1064
TH-201 : transferability of cathodal tDCS effects from the primary motor to the dorsolateral prefrontal cortex: a multimodal TMS-EEG study. - In: Clinical neurophysiology, ISSN 1872-8952, Bd. 141 (2022), S. S146-S147
https://doi.org/10.1016/j.clinph.2022.07.387
WE-123 : a 256-channel dry electrode cap for rapid high-density EEG. - In: Clinical neurophysiology, ISSN 1872-8952, Bd. 141 (2022), S. S63-S64
https://doi.org/10.1016/j.clinph.2022.07.167
Joint model order estimation for multiple tensors with a coupled mode and applications to the joint decomposition of EEG, MEG Magnetometer, and Gradiometer tensors. - In: 2022 IEEE International Conference on Acoustics, Speech, and Signal Processing, (2022), S. 1186-1190
The efficient estimation of an approximate model order is essential for applications with multidimensional data if the observed low-rank data is corrupted by additive noise. Certain signal processing applications such as biomedical studies, where the data are collected simultaneously through heterogeneous sensors, share some common features, i.e., coupled factors among multiple tensors. The exploitation of this coupling can lead to a better model order estimation, especially in case of low SNRs. In this paper, we extend the rank estimation techniques, designed for a single tensor, to noise-corrupted coupled low-rank tensors that share one of their factor matrices. To this end, we consider the joint effect of the global eigenvalues (calculated from the coupled HOSVD) and exploit the exponential behavior of the resulting coupled global eigenvalues. We show that the proposed method outperforms the classical criteria and can be successfully applied to EEG, MEG Magnetometer, and Gradiometer measurements. Our real data simulation results show that the estimated rank is highly reliable in terms of dominant components extraction.
https://doi.org/10.1109/ICASSP43922.2022.9747735
Neuronal sources of visually evoked potentials using selective color opponent channel stimulation. - In: Acta ophthalmologica, ISSN 1755-3768, Bd. 100 (2022), S267, insges. 1 S.
https://doi.org/10.1111/j.1755-3768.2022.064
Determination of the tonographic effect in the human eye using a pneumatic pressure modulator. - In: Acta ophthalmologica, ISSN 1755-3768, Bd. 100 (2022), S267, insges. 1 S.
https://doi.org/10.1111/j.1755-3768.2022.076
Light-field fundus imaging under astigmatism - an eye model study. - In: Acta ophthalmologica, ISSN 1755-3768, Bd. 100 (2022), S267, insges. 1 S.
https://doi.org/10.1111/j.1755-3768.2022.100