Fariba Karimi


Last Name

Karimi

First Name

Fariba

ORCID

0000-0002-2209-7590

Organisational unit

03741 - Vörös, Janos / Vörös, Janos

Filters

2023 - 20252
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Publications 1 - 2 of 2
  • Traceable Assessment of the Absorbed Power Density of Body Mounted Devices at Frequencies Above 10 GHz
    Item type: Journal Article
    Chitnis, Ninad; Karimi, Fariba; Kühn, Sven; et al. (2025)
    Bioelectromagnetics
    In this study, a comprehensive approach for the experimental assessment of the absorbed power density (APD) is developed. The method includes several novel components: (i) a specialized probe, (ii) a composite phantom, (iii) a reconstruction technique, (iv) a calibration method, and (v) a validation process. The described solution has been developed for the frequency range from 24 to 30 GHz, but can be extended to all frequency bands between 10 and 45 GHz. A novel composite phantom emulates the reflection and transmission coefficients of human skin for propagating and evanescent modes, while its increased penetration depth, in comparison to dermis tissue, enables the measurement of the induced electromagnetic fields (EMFs) with a new miniaturized dosimetric broadband probe. The implementation has a wide dynamic range and sufficient spatial resolution to use it for type approval of mobile devices. Its probe is calibrated with low uncertainty in a novel, traceable setup. A set of reference antennas with known numerical target values for the APD has been compiled to validate the measurement system. The validation demonstrates that the deviation is within the expanded uncertainty of 1.6 dB for pAPD and (Formula presented.) 1.5 dB for psAPD.
  • Theory for a non-invasive diagnostic biomarker for craniospinal diseases
    Item type: Journal Article
    Karimi, Fariba; Neufeld, Esra; Fallahi, Arya; et al. (2023)
    NeuroImage: Clinical
    Monitoring intracranial pressure (ICP) and craniospinal compliance (CC) is frequently required in the treatment of patients suffering from craniospinal diseases. However, current approaches are invasive and cannot provide continuous monitoring of CC. Dynamic exchange of blood and cerebrospinal fluid (CSF) between cranial and spinal compartments due to cardiac action transiently modulates the geometry and dielectric properties of the brain. The resulting impedance changes can be measured and might be usable as a non-invasive CC surrogate. A numerically robust and computationally efficient approach based on the reciprocity theorem was developed to compute dynamic impedance changes resulting from small geometry and material property changes. The approach was successfully verified against semi-analytical benchmarks, before being combined with experimental brain pulsation data to study the information content of the impedance variation. The results indicate that the measurable signal is dominated by the pulsatile displacement of the cortical brain surface, with minor contributions from the ventricular surfaces and from changes in brain perfusion. Different electrode setups result in complementary information. The information content from the investigated three electrode pairs was employed to successfully infer subject-specific brain pulsation and motion features. This suggests that non-invasive CC surrogates based on impedance monitoring could be established.
Publications 1 - 2 of 2