Using Dielectric Properties of Solid Fraction and Water Content to Characterize Tissues at Different Health and Age Conditions
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DPs of any healthy tissue can be described by DPs of its solid fraction and water content values. The observed DPs of a tissue change with the level of tissue’s water content (increase or decrease) according to the condition of the tissue (i.e., pathology and age). For the existing study, DPs of solid fraction and water content of 19 different tissues from 61 pigs at different ages were measured and used to generate DPs of those tissues under different conditions using a simple mathematical model. The dry-weighing method was used to determine the water content of tissues and DPs of their solid fractions were measured. Then, DPs of those tissues were generated using the proposed method and found to be in a good agreement with some previously published data as well as with the measured data in this study. This study confirms the potential of using DPs of the solid fraction and water content to calculate DPs of tissues at any age or pathology.
Effect of Dehydration on Dielectric Measurements of Biological Tissue as Function of Time
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Additionally, it proposes a dehydration mitigating technique. The dielectric properties of porcine liver samples were measured during a 35 minute measurement interval at different temperatures. A first set of six experiments was conducted in standard laboratory conditions. A second set of two experiments was conducted with a modified measurement setup with reduced air flow. Under standard conditions, relative changes in the dielectric properties up to 9% were observed. With the modified setup, the relative change was halved compared to standard conditions. This reduction indicates that the environmental conditions have a considerable influence and that modifying these conditions extends the stability of the dielectric properties over time. For several applications relying on the difference in dielectric properties between healthy and malignant tissue, an error of 9% in measured data is on the same order as the effects of interest. The expected difference in dielectric contrast could be obscured due to dehydration.
Real-Time Non-Contact Integrated Chipless RF Sensor for Disposable Microfluidic Applications
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The sensor is based on a microstrip line reader with defected ground plane coupled to a chipless microwave resonator tag. Due to the strong coupling between the reader and the tag, the distance between them can be increased up to 45 mm. The high level of sensitivity of the structure makes it suitable for nanolitre volume scale chemical sensing inside the microfluidic channel. The sensor demonstrates a frequency shift of 6 MHz when the volumetric percentage (V%) of glycerol in DI water changes from 70% to 0%. The proposed solution provides the opportunity of integrating the chipless passive tag with the microfluidic channel while the reader is distant from the microfluidic system.
Realization and Experimental Assessment of Baseball-Bat Microwave Antenna for Low Power Cancer Ablation
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Development of baseball-bat shaped (BSB) antenna has been studied using electromagnetic and thermal simulations and evaluated experimentally. Numerical simulations showed less than -10-dB reflection stability is attained for more than 20 GHz. Electromagnetic simulation showed that highly directed end-fire radiation achieves confined power deposition within targeted model and yields in higher SAR attained. Nearly spherical ablated lesions are achieved with no healthy tissues being destroyed in the backward direction. Proposed antenna was fabricated and tested in ex-vivo bovine liver sample and egg-white solution. Good agreement between simulated and measured results where confined ablated lesions attained at only 1W were comparable to that obtained at much higher power ranges (20-60W). Efficacy of BSB antenna to efficiently radiate in different dielectric mediums is noticeably attained. The proposed antenna model may help improving the precision of microwave ablation associated with commonly broadside radiators previously used in literature and provide homogenous SAR and confined heating to overcome the limitations found in treating spherical tumors with heterogeneous properties using much high power with narrow-band feature.
An invivo-mimickingIn vitrotestbed for brain-computer interfaces
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As such, optimizing and testing via function generators and resistors overestimates BCI sensitivity by at least 250 times and 2 times, respectively. To more closely replicate a clinical recording environment and accurately assess BCI performance, we utilize a function generator to mimic neural signals sent to a human-body-mimicking electrolyte fluid via a Pt electrode. These signals are then recorded via a neural electrode connected to the BCI under test. To validate the proposed method, we compare sensitivity of a previously reported fully passive BCI via the three methods. The presented results demonstrate that recording via the proposed clinically accurate setup when the BCI has been optimized with one of the two other test methods gives the lowest sensitivity in the frequency domain and worst signal stability in the time domain. Overestimating BCI sensitivity during in vitro testing results in the potential inability to record desired neural signals in vivo. The proposed method provides a means by which to accurately assess BCI performance, therefore reducing errors during animal trials and saving time, money, and lives.
Influence of low frequency Near-Field Sources Position on the Assessment of Children Exposure Variability using Stochastic Dosimetry
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In details, in this paper the exposure of two child models to a hairdryer model was evaluated. Following the ICNIRP guidelines, the electric field amplitudes induced in specific tissues composing the central nervous system and the peripheral nervous system were analyzed. The analysis of the results permitted to highlight a high exposure variability depending on the near-field source position and to individuate the regions where the source could cause the highest levels of exposure, not limiting the analysis only to some worst-case exposure scenarios.
