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Lung cancer is the most common and lethal cancer in many parts of the world. The establishment of lung cancer screening by low-dose computerized tomography (CT) scan has led to finding lung cancers in early stages as very small nodules. However, finding those nodules, particularly when located deep in the lung parenchyma, could be impossible during lung surgeries without preoperative or intraoperative localization. This study introduces a simple and safe method having the potential to localize in-depth pulmonary nodules intraoperatively. In this regard, a bioimpedance probe with four spherical electrodes was designed and built. By an in vitro study, the bioimpedance data of 286 lung tissue samples obtained from 38 patients in a frequency range of 50 kHz–5 MHz were collected and analyzed with Nyquist curves and boxplot charts. Finally, a smart system was designed based on the bioimpedance phase and magnitude to differentiate healthy lung tissue from the tumoral lung tissue. Our proposed system consists of two parts: the feature reduction with principal component analysis (PCA) and the classification with support vector machine (SVM), linear discriminant analysis (LDA), and K-nearest neighbors (KNN). Classifier analysis showed that the accuracy of all classifiers was more than 95% for 15 principal components; the SVM classifiers had the highest accuracy above 98%. This research sheds light on the feasibility of designing a real-time, safe, and smart system to localize the invisible/impalpable pulmonary nodules by the bioimpedance spectrum of the lung tissue.

Tissue electrical conductivity measurements are very important for diagnostic purposes. In this paper, an electrical bio-impedance sensor with a biopsy forceps shape was introduced for measuring electrical conductivity of the tissue inside the body. For this purpose, based on the Laplace’s equation and the forced boundary conditions in the mouth of the forceps, the relation between electrical conductivity of the tissue and measured electrical potential was analytically obtained. The obtained analytical formula was verified by modeling the electrical bio-impedance forceps and biological tissue in COMSOL software. A prototype of the designed bio-impedance forceps was fabricated and experimentally validated. The validation process was performed by measuring electrical conductivity of the Phosphate -Buffered Saline (PBS) solution with different concentrations. Finally, by measuring electrical impedance spectrum of pulmonary tissues in three different samples at a frequency band of 50 kHz to 5 MHz, it was found that this sensor could be potentially beneficial to discriminate tumoral tissues from healthy ones in biopsy process.

In this paper, a bioimpedance sensor used to measure the impedance behavior of the biological cells cultured on a scaffold of collagen thin films. The collagen thin films with different concentrations were created on a 1-hexadecanethiol modified surface of the interdigitated electrodes(IDEs). The mesenchymal stem cells(MSCs) and human umbilical vein endothelial cells(HUVECs) were cultured on the collagen thin films. The interaction and the proliferation rate of these cells were investigated by the microscopic, and bioimpedance approaches. Results showed that the MSCs, and HUVECs excellently attached to the collagen thin films. Impedance measurements of the cells cultured on the collagen thin film were performed by a Hioki IM3570 impedance analyzer at the frequency band of 10 kHz to 1MHz at 10 mV. Bioimpedance measurements showed that the proliferation rate of both MSCs, and HUVECs increased by decreasing the collagen thin films concentration. After 48 h, the differential impedances (ΔΖ ) of the MSCs cultured on the collagen thin layers with concentrations of 250μg/mL,500μg/mL , and 1000μg/mL measured 3.09Ω≤Δ≤48.03Ω, 2.62Ω≤Δ≤45.79Ω, and 1.9Ω≤Δ≤25.22Ω, respectively. Also, ΔΖ of the HUVECs obtained 27.3Ω≤Δ≤39.2Ω, 8.25Ω≤Δ≤18.43Ω, and 0.96Ω≤Δ≤9.6Ω for the corresponding frequency band and collagen thin films concentrations.